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Laboratory

Animal
Management

I I

Committee on Dogs

Institute of Laboratory Animal Resources

Commission on Life Sciences

National Research Council

NATIONAL ACADEMY PRESS
Washington, D.C. 1994

r> 'C ^

National Academy Press 2101 Constitution Avenue, N.W. Washington, D.C. 20418

NOTICE: The project that is the subject of this report was approved by the Governing Board
of the National Research Council, whose members are drawn from the councils of the National
Academy of Sciences, National Academy of Engineering, and Institute of Medicine. The
members of the committee responsible for the report were chosen for their special competen-
cies and with regard for appropriate balance.

This report has been reviewed by a group other than the authors according to procedures
approved by a Report Review Committee consisting of members of the National Academy of
Sciences, National Academy of Engineering, and Institute of Medicine.

This study was supported by the U.S. Department of Health and Human Services (DHHS)
through contract number NO1-CM-07316 with the Division of Cancer Treatment, National
Cancer Institute; the Animal Welfare Information Center, National Agricultural Library, U.S.
Department of Agriculture (USDA), through grant number 59-32U4-8-60; and Regulatory En-
forcement and Animal Care, Animal and Plant Health Inspection Service, USDA, through
grant number 59-32U4-8-60. Additional support was provided by the following members of
the Pharmaceutical Manufacturers Association: Berlex Laboratories, Inc., Cedar Knolls, New
Jersey; Bristol-Myers Squibb Co., New York, New York; Bristol-Myers Research, Princeton,
New Jersey; Burroughs Wellcome Co., Research Triangle Park, North Carolina; Dupont Merck
Research & Development, Wilmington, Delaware; Johnson & Johnson, New Brunswick, New
Jersey; Marion Merrell Dow Inc., Kansas City, Missouri; Pfizer Inc., Groton, Connecticut;
Schering-Plough Research, Bloomfield, New Jersey; SmithKline Beecham Pharmaceuticals,
Swedeland, Pennsylvania; and Syntex Research, Palo Alto, California.

ILAR's core program is supported by grants from the National Center for Research
Resources, National Institutes of Health; National Science Foundation; American Cancer Soci-
ety, Inc.; and U.S. Army Medical Research and Development Command, which is the lead
agency for combined Department of Defense funding also received from the Human Systems
Division, Air Force Systems Command; Armed Forces Radiobiology Research Institute; Uni-
formed Services University of the Health Sciences; and U.S. Naval Medical Research and
Development Command.

Any opinions, findings, and conclusions or recommendations expressed in this publica-
tion are those of the committee and do not necessarily reflect the views of DHHS, USDA, or
other sponsors, nor does the mention of trade names, commercial products, or organizations
imply endorsement by the U.S. government or other sponsor.

Library of Congress Cataloging-in-Publication Data

Dogs : laboratory animal management / Committee on Dogs, Institute of
Laboratory Animal Resources, Commission on Life Sciences, National
Research Council.

p. cm.

Includes bibliographical references and index.
ISBN 0-309-04744-7

1. Dogs as laboratory animals. I. Institute of Laboratory Animal
Resources (U.S.). Committee on Dogs.
SF407.D6D64 1994

636.7'0885 dc20 94-960

CIP

COMMITTEE ON DOGS

Fred W. Quimby (Chairman), Center for Research Animal Resources,

New York State College of Veterinary Medicine, Cornell University,

Ithaca, New York
Emerson L. Besch, Department of Physiological Sciences, University of

Florida College of Veterinary Medicine, Gainesville, Florida
Linda C. Cork, Department of Comparative Medicine, Stanford

University, Stanford, California

Suzanne Hetts, Humane Society of Denver, Denver, Colorado
Warren C. Ladiges, Department of Comparative Medicine, University of

Washington, Seattle, Washington
Richard J. Traystman, Department of Anesthesiology and Critical Care

Medicine, The Johns Hopkins Hospital, Baltimore, Maryland

Staff

Dorothy D. Greenhouse, Project Director
Amanda E. Hull, Project Assistant
Norman Grossblatt, Editor

The Institute of Laboratory Animal Resources (ILAR) was founded in
1952 under the auspices of the National Research Council. A component of
the Commission on Life Sciences, ILAR serves as a coordinating agency
and a national and international resource for compiling and disseminating
information on laboratory animals, promoting education, planning and con-
ducting conferences and symposia, surveying existing and required facili-
ties and resources, upgrading laboratory animal resources, and promoting
high-quality, humane care of laboratory animals in the United States.

University Libraries

CONTRIBUTORS

Gregory M. Acland, James A. Baker Institute, Cornell University, Ithaca,

New York

Judith A. Bell, Marshall Research Animals, North Rose, New York
Dwight D. Bowman, New York State College of Veterinary Medicine,

Cornell University, Ithaca, New York
David P. Brooks, SmithKline Beecham Pharmaceuticals, King of Prussia,

Pennsylvania
Phillip R. Brown, Division of Comparative Medicine, The Johns Hopkins

University School of Medicine, Baltimore, Maryland
Robert W. Bull, Michigan State University, East Lansing, Michigan
Leland E. Carmichael, James A. Baker Institute, Cornell University,

Ithaca, New York
J. Derrell Clark, Animal Resources, University of Georgia College of

Veterinary Medicine, Athens, Georgia
Patrick W. Concannon, New York State College of Veterinary Medicine,

Cornell University, Ithaca, New York
Lawrence G. Carbone, New York State College of Veterinary Medicine,

Cornell University, Ithaca, New York
Laurel J. Dungan, Department of Comparative Medicine, Medical

University of South Carolina, Charleston, South Carolina
W. Jean Dodds, Hemopet, Santa Monica, California
Robin D. Gleed, New York State College of Veterinary Medicine, Cornell

University, Ithaca, New York
Arthur S. Hall, Department of Animal Care, Oregon Health Sciences

University, Portland, Oregon
Margaret S. Landi, SmithKline Beecham Pharmaceuticals, King of

Prussia, Pennsylvania
George Lust, James A. Baker Institute, Cornell University, Ithaca, New

York
Ronald R. Minor, New York State College of Veterinary Medicine,

Cornell University, Ithaca, New York
Bruce A. Muggenburg, Inhalation Toxicology Research Institute,

Albuquerque, New Mexico
Bryan E. Ogden, Department of Animal Care, Oregon Health Sciences

University, Portland, Oregon

Donald F. Patterson, Section of Medical Genetics, University of
Pennsylvania School of Veterinary Medicine, Philadelphia,
Pennsylvania

Arleigh Reynolds, New York State College of Veterinary Medicine,
Cornell University, Ithaca, New York

Robert M. Shull, Department of Pathobiology, University of Tennessee

College of Veterinary Medicine, Knoxville, Tennessee
Alison C. Smith, Department of Comparative Medicine, Medical

University of South Carolina, Charleston, South Carolina
Rainer F. Storb, Fred Hutchinson Cancer Research Center, Seattle,

Washington
M. Michael Swindle, Department of Comparative Medicine, Medical

University of South Carolina, Charleston, South Carolina
Beth A. Valentine, Department of Pathology, New York State College of

Veterinary Medicine, Cornell University, Ithaca, New York
David A. Valerio, Hazleton Research Products, Denver, Pennsylvania

INSTITUTE OF LABORATORY ANIMAL RESOURCES COUNCIL

John L. VandeBerg (Chairman), Southwest Foundation for Biomedical

Research, San Antonio, Texas

Christian R. Abee, University of South Alabama, Mobile, Alabama
J. Derrell Clark, University of Georgia College of Veterinary Medicine,

Athens, Georgia

Muriel T. Davisson, The Jackson Laboratory, Bar Harbor, Maine
Neal L. First, University of Wisconsin, Madison, Wisconsin
James W. Glosser, University of California School of Veterinary

Medicine, Davis, California

Jon W. Gordon, Mt. Sinai School of Medicine, New York, New York
John P. Hearn, Wisconsin Regional Primate Research Center, Madison,

Wisconsin

Margaret Z. Jones, Michigan State University, East Lansing, Michigan
Michael D. Kastello, Merck Sharp & Dohme, Rahway, New Jersey
Charles R. McCarthy, Kennedy Institute of Ethics, Georgetown

University, Washington, D.C.
Richard C. Van Sluyters, University of California School of Optometry,

Berkeley, California
Peter A. Ward, University of Michigan School of Medicine, Ann Arbor,

Michigan

Staff

Eric A. Fischer, Director

COMMISSION ON LIFE SCIENCES

Thomas D. Pollard (Chairman), The Johns Hopkins University School of

Medicine, Baltimore, Maryland

Bruce N. Ames, University of California, Berkeley, California
John C. Bailar III, McGill University, Montreal, Quebec, Canada
J. Michael Bishop, University of California Medical Center, San

Francisco, California
John E. Burris, Marine Biological Laboratory, Woods Hole,

Massachusetts

Michael T. Clegg, University of California, Riverside, California
Glenn A. Crosby, Washington State University, Pullman, Washington
Leroy E. Hood, University of Washington, Seattle, Washington,
Marian E. Koshland, University of California, Berkeley, California
Richard E. Lenski, Michigan State University, East Lansing, Michigan
Emil A. Pfitzer, Hoffmann-La Roche Inc., Nutley, New Jersey
Malcolm C. Pike, University of Southern California School of Medicine,

Los Angeles, California

Henry C. Pitot III, University of Wisconsin, Madison, Wisconsin
Paul G. Risser, Miami University, Oxford, Ohio
Jonathan M. Samet, University of New Mexico School of Medicine,

Albuquerque, New Mexico
Harold M. Schmeck, Jr., Armonk, New York
Carla J. Shatz, University of California, Berkeley, California
Susan S. Taylor, University of California at San Diego, La Jolla,

California
John L. VandeBerg, Southwest Foundation for Biomedical Research, San

Antonio, Texas

P. Roy Vagelos, Merck & Co., Whitehouse Station, New Jersey
Torsten N. Wiesel, Rockefeller University, New York, New York

Staff

Paul Oilman, Executive Director

VII

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of
distinguished scholars engaged in scientific and engineering research, dedicated to the further-
ance of science and technology and to their use for the general welfare. Upon the authority of
the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to
advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is
president of the National Academy of Sciences.

The National Academy of Engineering was established in 1964, under the charter of the
National Academy of Sciences, as a parallel organization of outstanding engineers. It is
autonomous in its administration and in the selection of its members, sharing with the National
Academy of Sciences the responsibility for advising the federal government. The National
Academy of Engineering also sponsors engineering programs aimed at meeting national needs,
encourages education and research, and recognizes the superior achievements of engineers.
Dr. Robert M. White is president of the National Academy of Engineering.

The Institute of Medicine was established in 1970 by the National Academy of Sciences
to secure the services of eminent members of appropriate professions in the examination of
policy matters pertaining to the health of the public. The Institute acts under the responsibility
given to the National Academy of Sciences by its congressional charter to be an adviser to the
federal government and upon its own initiative to identify issues of medical care, research, and
education. Dr. Kenneth I. Shine is president of the Institute of Medicine.

The National Research Council was established by the National Academy of Sciences in
1916 to associate the broad community of science and technology with the Academy's pur-
poses of furthering knowledge and advising the federal government. Functioning in accor-
dance with general policies determined by the Academy, the Council has become the principal
operating agency of both the National Academy of Sciences and National Academy of Engi-
neering in the conduct of their services to the government, the public, and the scientific and
engineering communities. The Council is administered jointly by both Academies and the
Institute of Medicine. Dr. Bruce M. Alberts and Dr. Robert M. White are chairman and vice-
chairman, respectively, of the National Research Council.

Vlll

Preface

It has been 2 decades since the Institute of Laboratory Animal Re-
sources first published Dogs: Standards and Guidelines for the Breeding,
Care, and Management of Laboratory Animals (National Academy of Sci-
ences, Washington, D.C., 1973). During that period, great strides have
been made in improving care and management techniques, making available
specific-pathogen-free and purpose-bred dogs, and identifying dogs with
precisely defined genetic disorders. The dog has proved to be "man's best
friend," not only because it is considered a companion and family member,
but also because its use in research has been associated with many break-
through discoveries in human medicine (e.g., the discovery of insulin as a
treatment for type I diabetes mellitus).

The same period has been characterized by increased public awareness
and scrutiny of research funding, occupational health and safety, and animal
welfare. New federal and state laws specifically intended to protect re-
search animals have been promulgated and regulations established. In addi-
tion to presenting information relevant to the care and use of dogs in re-
search and making recommendations based on an objective evaluation of
that information, it was the committee's intent to incorporate in this report
those aspects of canine husbandry embodied in federal law. Federal regula-
tions and policies protecting dogs in research are therefore summarized in
Chapter 1, which provides information for obtaining copies. Specific de-
tails of the regulations and policies are given throughout the text.

X PREFACE

The committee firmly believes that good research requires a good ani-
mal-care program. The committee is also aware of the tremendous varia-
tion in physiologic traits among canine models. Dogs vary greatly in size,
age, health status, physical conformation of the breed, behavioral character-
istics, and experience. Therefore, no standard of animal care is likely to be
optimal for all dogs. The committee recommends that performance stan-
dards be used with sound professional judgment in implementing the ani-
mal-care program.

Readers who detect errors of omission or commission or who have
evidence to support improved procedures are invited to send suggestions to
ILAR, National Research Council, 2101 Constitution Avenue, Washington,
DC 20418.

The committee wishes to thank the entire staff of ILAR, but especially
Dr. Dorothy Greenhouse and Ms. Amanda Hull, for assisting in the produc-
tion of this manuscript. The committee also acknowledges the many fine
contributions made to this report by scientists specializing in the care and
use of dogs in research; their names appear on pages iv and v.

Fred W. Quimby, Chairman
Committee on Dogs

Contents

1 INTRODUCTION 1

References 3

2 CRITERIA FOR SELECTING EXPERIMENTAL ANIMALS 4

Genetic Factors 5
Biologic Factors 7
Behavioral Factors 7
Hazards 9
References 9

3 HUSBANDRY 11

Housing 12

Exercise and Environmental Enrichment 21

Food 24

Water 26

Bedding and Resting Apparatuses 26

Sanitation 27

Identification and Records 27

Emergency, Weekend, and Holiday Care 29

Transportation 39

References 32

Xll CONTENTS

4 MANAGEMENT OF BREEDING COLONIES 35
Reproduction 35

Neonatal Care 40

Reproductive Problems 41

Special Nutritional Requirements 42

Vaccination and Deworming 43

Socialization of Pups 44

Record Keeping 46

References 47

5 VETERINARY CARE 51
Procurement 52

Control of Infectious Diseases 53

Control of Parasitic Diseases 57

Recognition and Alleviation of Pain and Distress 63

Surgery and Postsurgical Care 68

Euthanasia 70

References 72

6 SPECIAL CONSIDERATIONS 75
Protocol Review 76

Restraint 78

Special Care for Animal Models 78

Aging 79

Cardiovascular Diseases 81

Ehlers-Danlos Syndrome 91

Endocrinologic Diseases 93

Hematologic Disorders 97

Immunologic Diseases 101

Lysosomal Storage Diseases 107

Muscular Dystrophy 1 1

Neurologic Disorders 1 1 2

Ophthalmologic Disorders 1 14

Orthopedic Disorders 1 1 6

Radiation Injury 117

Gene Therapy 119
References 122

APPENDIX: CROSS REFERENCE 131

INDEX

Laboratory

Mimal
Management

Introduction

Dogs make valuable contributions in biomedlcal research because they
share many biochemical and physiologic characteristics with humans and
spontaneously develop disorders that are homologous to pathologic condi-
tions in humans. While using them as models for human disease, we have
also learned much about normal physiologic processes in dogs themselves.
Advances in molecular genetics, reproduction, behavior, immunology, he-
matology, endocrinology, microbiology, nutrition, pharmacology, and oncology,
to name a few, have made dogs more valuable as models and, at the same
time, have provided veterinarians with useful information for the diagnosis
and treatment of canine diseases.

In the past 2 decades, two amendments to the Animal Welfare Act (in
1976 and 1985) and a section added to the Health Research Extension Act
of 1985 have resulted in revised standards for dogs. Institutions that use
dogs must comply with the Code of Federal Regulations, Title 9, Subchapter
A, Parts 1-3 (9 CFR 1-3), commonly called the Animal Welfare Regulations
(AWRs), which were promulgated to administer the Animal Welfare Act.
Institutions receiving Public Health Service (PHS) funding must also com-
ply with the Public Health Service Policy on Humane Care and Use of
Laboratory Animals (hereafter called the PHS Policy) (PHS, 1986), which
in turn requires compliance with the Guide for the Care and Use of Labora-
tory Animals (hereafter called the Guide) (NRC, 1985). Some of the AWRs
are based on engineering standards (e.g., that on space requirements for
dogs), but most rely on performance standards (i.e., the demonstration of

2 DOGS: LABORATORY ANIMAL MANAGEMENT

animal well-being). It is expected, therefore, that professional judgment
will be used in applying the AWRs. It is also incumbent on all people using
dogs to seek improvements in the methods for using them.

This edition of Dogs: Laboratory Animal Management incorporates fea-
tures of housing, management, and care that are related to the expanded use
of dogs as models of human diseases and an intrepretative summary of the
AWRs and requirements of the PHS Policy. The appendix lists subjects
within this text by page number with cross references to corresponding
sections in the AWRs and the Guide. The regulations, policies, and guide-
lines that are applicable to dogs include the following:

Code of Federal Regulations, Title 9, Subchapter A, Parts 1 -3 (commonly
called the Animal Welfare Regulations). Available from Regulatory En-
forcement and Animal Care, APHIS, USDA, Federal Building, Room 565,
6505 Belcrest Road, Hyattsville, MD 20782 (telephone, 301-436-7833).

Public Health Service Policy on Humane Care and Use of Labora-
tory Animals. Available in English or Spanish from the Office for Protec-
tion from Research Risks, Building 31, Room 5B59, NIH, Bethesda, MD
20892 (telephone, 301-496-7163).

Guide for the Care and Use of Laboratory Animals. Available in
English or Spanish from the Office for Protection from Research Risks,
Building 31, Room 5B59, NIH, Bethesda, MD 20892 (telephone: 301-496-
7163). Single copies (English only) available from the Institute of Labora-
tory Animal Resources, National Research Council, 2101 Constitution Av-
enue NW, Washington, DC 20418 (telephone, 202-334-2590).

Code of Federal Regulations, Title 21, Part 58; Title 40, Part 160;
and Title 40, Part 792 (commonly called the Good Laboratory Practice, or
GLP, Standards). Available from the Superintendent of Documents, U.S.
Government Printing Office, Washington, DC 20402 (telephone, 202-783-
3238).

IATA Live Animal Regulations. Available in English, French, or
Spanish from the International Air Transport Association (IATA), 2000 Peel
Street, Montreal, Quebec, Canada H3A 2R4 (telephone, 514-844-631 1).

All animals used in research must be treated with the dignity and re-
spect due living beings. Those who use animals in experiments must there-
fore be properly trained in methods appropriate for the species used. It is
the responsibility of each research facility to develop educational programs
for animal-care providers and the research staff (9 CFR 2.32). Recommen-
dations for establishing such programs have recently been published (NRC
1991).

INTRODUCTION

REFERENCES

NRC (National Research Council), Institute of Laboratory Animal Resources, Committee on
Care and Use of Laboratory Animals. 1985. Guide for the Care and Use of Laboratory
Animals. NIH Pub. No. 86-23. Washington, D.C.: U.S. Department of Health and
Human Services, 83 pp.

NRC (National Research Council), Institute of Laboratory Animal Resources, Committee on
Educational Programs in Laboratory Animal Science. 1991. Education and Training in
the Care and Use of Laboratory Animals: A Guide for Developing Institutional Pro-
grams. Washington, D.C.: National Academy Press. 139 pp.

PHS (Public Health Service). 1986. Public Health Service Policy on Humane Care and Use of
Laboratory Animals. Washington, D.C.: U.S. Department of Health and Human Ser-
vices. 28 pp.

Criteria for Selecting
Experimental Animals

Scientists who are planning experiments evaluate both animal and nonanimal
approaches. If there are no suitable alternatives to the use of live animals,
the appropriate species is selected on the basis of various scientific and
practical factors, including the following:

Which species will yield the most scientifically accurate and inter-
pretable results?

According to critical review of the scientific literature, which spe-
cies have provided the best, most applicable historical data?

On which species will data from the proposed experiments be most
relevant and useful to present and future investigators?

Which species have special biologic or behavioral characteristics
that make them most suitable for the planned studies?

Which species have features that render them inappropriate for the
planned studies?

Which species present the fewest or least severe biologic hazards to
the research team?

Which species require the fewest number of animals?

Which species that meet the above criteria are most economical to
acquire and house?

For many scientific experiments, the answer to those questions will be
the domestic dog, Canis familiaris. The size, biologic features, and coop-

CRITERIA FOR SELECTING EXPERIMENTAL ANIMALS 5

erative, docile nature of the well-socialized dog make it the model of choice
for a variety of scientific inquiries. The contributions of the dog to human
health and well-being are numerous (Gay, 1984).

Although research with dogs is often primarily to benefit humans, it has
also greatly benefited dogs that are kept as companion animals. Examples
of the benefits to dogs are improvements in diagnostic techniques; treat-
ments for diabetes and arthritis; surgical procedures for correcting or treat-
ing cardiovascular, orthopedic, and neurologic disorders; and therapies for
bacterial, neoplastic, and autoimmune diseases. Moreover, dogs have been
necessary for the development of vaccines that protect companion animals
against viral diseases (e.g., distemper and parvovirus disease) and drugs
that prevent parasitic diseases (e.g., dirofilariasis, or heartworm disease).

GENETIC FACTORS

All domestic dogs, irrespective of breed, are Canis familiaris. Canine
genotypes and phenotypes vary among breeds as a result of selective breed-
ing, which has created variations in allele frequency between breeds. Al-
though "pure" breeds might have a higher frequency of some genes, much
genetic variation remains in most breeds.

The canine karyotype consists of 78 chromosomes (Minouchi, 1928).
Most of the autosomes are acrocentric or telocentric, and many pairs do not
differ markedly in size. Recently, an improved method for staining canine
chromosomes has been developed that makes karyotyping with Giemsa banding
feasible (Stone et al., 1991).

A number of loci have been identified that code for the antigens of the
canine major histocompatibility complex, which has been designated DLA
(Vriesendorp et al., 1977). Initially, several alleles were defined with sero-
logic techniques at three class I loci, and several alleles were defined with
cellular techniques at a DLA class II locus (Bull et al., 1987; Deeg et al.,
1986). Molecular techniques are being used to refine the definition of the
DLA class I loci, and at least eight class I genes have been demonstrated in
the dog (Sarmiento and Storb, 1989). Molecular-genetic studies to charac-
terize canine class II loci correlate well with earlier work in which tech-
niques for cell typing for class II antigens were used (Sarmiento and Storb,
1988a,b). The characterization of canine DLA loci is extremely useful for
transplantation studies (Ladiges et al., 1985) and for demonstrating an asso-
ciation between the major histocompatibility complex and some inherited
canine diseases (Teichner et al., 1990).

Attempts are under way to develop maps that identify the location of
canine genes that control particular traits (e.g., inherited diseases and such
behavioral tendencies as herding and aggression). Two approaches are used.
The first relies on the principle that the relative positions of genes in a

6 DOGS: LABORATORY ANIMAL MANAGEMENT

particular region of DNA are comparable in humans, dogs, and other spe-
cies. Conserved regions can be identified in DNA samples with restriction-
fragment length polymorphisms (usually called RFLPs) that have been identified
with probes for human and murine genes whose chromosomal locations are
known. To enhance the detection of polymorphisms, investigators some-
times produce dog-coyote hybrids, cross-breed two widely divergent dog
breeds, or analyze a large, well-defined canine kindred (Joe Templeton,
Department of Veterinary Pathobiology, College of Veterinary Medicine,
Texas A&M University, College Station, Tex., personal communication,
1993). The second approach uses simple sequence-repeat polymorphisms
(microsatellite probes). Specific simple sequence-repeat markers that are
highly polymorphic in dogs have been developed to study the canine ge-
nome (Ostrander et al., 1992, 1993). These and other techniques, such as
chromosomal in situ hybridization and somatic cell hybridization, will likely
greatly increase our understanding of canine genetics.

Inherited defects including lysosomal storage diseases, retinal degen-
erations, coagulopathies, complement deficiency, and various musculoskel-
etal, hematopoietic, immunologic, and neurologic diseases are common in
purebred dogs, and many specific disorders are found most commonly in
particular breeds (Patterson et al., 1989). This phenomenon might be re-
lated, in part, to breeders' inadvertent selection for mutant alleles that are
closely linked to loci that determine breed-typical traits or to the chance
increase in frequency of particular mutant alleles caused by the founder
effect or random genetic drift. The high frequency of inherited canine
disorders (compared with murine disorders) was recognized as early as 1969
(Cornelius, 1969). During the 20-year period 1960-1980, 20 percent of
more than 1,200 literature citations on naturally occurring animal models of
human diseases involved dogs (Hegreberg and Leathers, 1980). A compila-
tion in 1989 noted that 281 inherited disease entities had been reported in
dogs (Patterson et al., 1989). Many of those constitute the only animal
models for investigating the corresponding human diseases (Patterson et al.,
1988). The l9-f&scic\Q Handbook: Animal Models of Human Disease (RCP,
1972-1993) lists 83 canine models of human diseases, many of which are
hereditary, and the two-volume Spontaneous Animal Models of Human Dis-
ease (Andrews et al., 1979) describes many canine models.

In scientific studies in which genetic uniformity is desirable or in long-
term studies in which the expected differences between experimental and
control subjects are likely to be small, purpose-bred dogs (e.g., beagles)
might be a more appropriate choice than dogs of unknown provenance. An
advantage of using beagles, as opposed to other purpose-bred dogs, is the
potential availability of other members of the kindred. But if the studies are
to determine the greatest range of a variable that is likely to occur among
the experimental subjects or if the experiments are of short duration, ran-

CRITERIA FOR SELECTING EXPERIMENTAL ANIMALS 7

dom-source dogs might be more useful and less expensive (see "Procure-
ment" in Chapter 5).

BIOLOGIC FACTORS

Dogs are monogastric carnivores with a short generation time (i.e., the
calculated interval between when a pup is born and when its first offspring
could be born) and a maximum life span of approximately 20 years; larger
breeds appear to have a shorter maximum life span than smaller breeds.
The canine mortality rate doubles every 3 years, compared with every 0.3
year for the rat (maximum life span, 5.5 years), every 15 years for the
rhesus monkey (maximum life span, more than 35 years), and every 8 years
for humans (maximum life span, more than 110 years) (Finch et al., 1990).
Dogs are useful models for studying the lifetime effects of environmental
factors, and there is an extensive literature on their use in radiation biology
(see Gay, 1984; Shifrine and Wilson, 1980).

Selective breeding has resulted in a spectrum of behaviors and a large
range of canine body sizes, from the giant breeds (e.g., Irish wolfhound),
which can measure 91 cm (36 in) at the shoulder and weigh more than 56
kg (124 Ib), to the toy breeds (e.g., Pomeranian), which can measure less
than 31 cm (12 in) in height and weigh less than 4.5 kg (10 Ib). Larger
dogs, which can include mongrels or dogs of unknown breeding, are par-
ticularly well suited to cardiovascular, transplantation, and orthopedic stud-
ies, because body weights and blood volumes approximate those of humans
(see Gay, 1984; Shifrine and Wilson, 1980; Swindle and Adams, 1988).
The dog's size also lends itself to procedures that cannot be carried out in
smaller species, e.g., when the instrumentation essential for collecting sci-
entific data is bulky and cannot be miniaturized and when the resolution of
imaging equipment requires a larger target field than is available in a small
animal.

An individual dog often can be studied in great detail or in many ways,
which might reduce the number of subjects needed for a study and generate
a more definitive data set. For example, it is possible to take multiple blood
samples of several milliliters each from a single dog over some period
without compromising the dog's well-being, but taking samples of similar
size during the same period from a single mouse or rat would be impossible.

BEHAVIORAL FACTORS

The social unit for dogs is the pack, and most dogs can be socialized to
accept humans as the dominant individual in their social hierarchy, espe-
cially if the techniques used to socialize them provide rewarding experi-
ences (e.g., food treats, petting, and verbal reinforcements) and minimize

DOGS: LABORATORY ANIMAL MANAGEMENT

TABLE 2.1 Selected Canine* Zoonoses

Disease in Humans

Agent

Mode of Transmission
(Intermediate Host or Vector)^

Acariasis

Cheyletiella yasguri

Direct

Amebiasis

Entamoeba histolytica

Direct

American trypanosomiasis

Trypanosoma cruzi

Indirect (triatomine insect)

(Chagas' disease)

Brucellosis

Brucella canis

Direct

Campylobacteriosis

Campy lobacter jejuni

Direct

Coenurosis

Taenia multiceps

Direct

Colibacillosis

Enteropathogenic Escherichia

coli

Direct

Cutaneous larva migrans

Ancylostoma braziliense

Ancylostoma caninum

Direct

Dipylidiasis

Dipylidium caninum

Indirect (dog flea)

Df2 infections

Dysgonic fermenter-2

Direct

Dirofilariasis

Dirofilaria immitis

Dirofilaria rep ens

Indirect (mosquito)

Giardiasis

Giardia intestinalis (canis}

Direct

Hydatidosis

Echinococcus granulosus

Direct

Larva currens

Strongyloides stercoralis

Direct

Leishmaniasis (cutaneous)

Leishmania braziliensis

peruviana

Indirect (phlebotomine flies)

Leishmaniasis (visceral)

Leishmania donovani

Indirect (phlebotomine flies)

Leptospirosis

Leptospira spp.

Direct

(usually L. canicola)

Pasteurellosis

Pasteurella multocida

Direct

Rabies

Rabies virus

Direct

Ringworm

Microsporum canis

Direct

(dermatomycoses)

Trichophyton mentagrophytes

Rocky Mountain

Rickettsia rickettsii

Indirect (tick)

spotted fever

Salmonellosis

Salmonella spp.

Direct

Scabies

Sarcoptes scabiei

Direct

Tularemia

Francisella tularensis

Indirect (tick)

Visceral larva migrans

Toxacara canis

Direct

Toxascaris leonina

Yersiniosis

Yersinia enterocolitica

Direct

J North, Central, and South American dogs.

^Direct = transmission by direct contact with the dog, its excretions, or its secretions; no
other vector or intermediate host is required.

aversive experiences. Different breeds and individual dogs differ in the
ease and rapidity with which they can be socialized to humans (Scott and
Fuller, 1965). However, properly socialized dogs can be docile and can be
trained to cooperate in procedures that require repeated contacts with re-
search personnel. For example, most dogs will allow venipuncture with

CRITERIA FOR SELECTING EXPERIMENTAL ANIMALS 9

minimal restraint and will cooperate during detailed physical and neuro-
logic evaluations.

HAZARDS

Unvaccinated dogs might harbor rabies virus, and preexposure immuni-
zation should be made available to personnel who are at substantial risk of
infection (NRC, 1985). Dogs also have internal and external parasites that
can be shared with humans (see "Parasitic Diseases" in Chapter 5). Table
2.1 lists selected zoonoses, zoonotic agents, and modes of transmission.
Detailed discussions of zoonoses have been published (Acha and Szyfres,
1987; August, 1988; Elliot et al., 1985; Fishbein and Robinson, 1993; Hubbert
et al., 1975). Personnel can develop allergies to canine dander and saliva,
can be bitten or scratched, might suffer hearing impairment from prolonged
exposure to excessive noise generated by barking dogs or mechanical equipment,
or can be injured while lifting or transporting large dogs. To deal with
these and other animal-related health problems, institutions must provide
occupational health programs for personnel who work in animal facilities or
have substantial animal contact (NRC, 1985),

REFERENCES

Acha, P. N., and B. Szyfres. 1987. Zoonoses and Communicable Diseases Common to Man

and Animals, 2d ed. Scientific Pub. No. 503. Washington, D.C.; Pan American Health

Organization. 963 pp.
Andrews, E. J., B. C. Ward, and N. H. Altman, eds. 1979. Spontaneous Animal Models of

Human Disease. New York: Academic Press. Vol. I, 322 pp.; vol. II, 324 pp,
August, J. R. 1988. Dygonic fermenter-2 infections. J. Am. Vet. Med, Assoc. 193:1506-

1508.
Bull, R. W., H. M. Vriesendorp, R. Cech, H. Grosse-Wilde, A. M. Bijma, W. L. Ladiges, K.

Krumbacher, I. Doxiadis, H. Ejima, J. Templeton, E. D. Albert, R, Storb, and H. J, Deeg.

1987. Joint report of the Third International Workshop on Canine Immunogenetics, II.

Analysis of the serological typing of cells. Transplantation 43:154-161.
Cornelius, C. E. 1969. Animal models A neglected medical resource. N, Engl. J. Med.

281:934-944.
Deeg, H. J., R. R Raff, H. Grosse-Wilde, A. M. Bijma, W. A, Buurman, I, Doxiadis, H. J.

Kolb, K. Krumbacher, W. Ladiges, K, L. Losslein, G. Schoch, D. L. Westbroek, R, W.

Bull, and R. Storb. 1986. Joint report of the Third International Workshop on Canine

Immunogenetics. I. Analysis of homozygous typing cells. Transplantation 41:111-1 17.
Elliot, D. L., S. W. Tolle, L. Goldberg, and J. B. Miller. 1985. Pet-associated illness. N,

Engl. J. Med. 313:985-995,
Finch, C. E., M. C. Pike, and M. Witten. 1990. Slow mortality rate accelerations during aging

in some animals approximate that of humans. Science 249:902-905.
Fishbein, D. B., and L. E. Robinson. 1993. Rabies. N. Engl. J. Med, 329:1632-1638.
Gay, W.I. 1984. The dog as a research subject. The Physiologist 27:133-141.
Hegreberg, G., and C. Leathers, eds. 1980. Bibliography of Naturally Occurring Animal

Models of Human Disease. Pullman, Washington: Student Book Corp. 146 pp.

10 DOGS: LABORATORY ANIMAL MANAGEMENT

Hubbert, W. T., McCuUoch, W. R, and Schnurrenberger, P. R., eds. 1975. Diseases Transmit-

ted from Animals to Man, 6th ed. Springfield: 111: Charles C Thomas. 1,236pp.
Ladiges, W. C, H. J. Deeg, R. F. Raff, and R. Storb. 1985. Immunogenetic aspects of a

canine breeding colony. Lab. Anim. Sci. 35(l):58-62.
Minouchi, 0. 1928. The spermatogenesis of the dog with special reference to meiosis. Jpn. J.

Zool. 1:255-268.

Ostrander, E. A., P. M. Jong, J. Rine, and G. Duyk. 1992. Construction of small-insert
genomic DNA libraries highly enriched for microsatellite repeat sequences. Proc. Natl
Acad. Sci. USA 89:3419-3423.
Ostrander, E. A., G. R Sprague, Jr., and J. Rine. 1993. Identification and characterization of

dinucleotide repeat (CA) n markers for genetic mapping in dog. Genomics 16:207-213.
Patterson, D. F., M. E. Haskins, P. F. Jezyk, U. Giger, V. N. Meyers- Wallen, G. Aguirre, J. C.
Fyfe, and J. H. Wolfe. 1988. Research on genetic diseases: Reciprocal benefits to
animals and man. J. Am. Vet. Med. Assoc. 193:1 131-1 144.

Patterson, D. F., G. A. Aguirre, J. C. Fyfe, U. Giger, P. L. Green, M. E. Haskins, P. F. Jezyk,
and V. N. Meyers-Wallen. 1989. Is this a genetic disease? J. Small Anim. Pract
30:127-139.

RCP (Registry of Comparative Pathology). 1972-1993. Handbook: Animal Models of Human
Disease, fascicles 1-19. Washington, D.C.: Registry of Comparative Pathology. Avail-
able from RCP, Armed Forces Institute of Pathology, Washington, DC 20306-6000
Sanniento, U. M., and R. F. Storb. 1988a. Characterization of class II alpha genes and DLA-

D region allelic associations in the dog. Tissue Antigens 32:224-234
Sanniento, U. M., and R. F. Storb. 1988b. Restriction fragment length polymorphism of the

major histocompatibility complex of the dog. Immunogenetics 28- 1 1 7- 1 24
Sarmiento, U. M., and R. F. Storb. 1989. RFLP analysis of DLA class I genes in the dog
Tissue Antigens 34:158-163. *"

Scott J. P., and J. L. Fuller. 1965. Genetics and the Social Behavior of the Dog. Chicago-
University of Chicago Press. 468pp. fc

Shifrine, M and F. D. Wilson, eds. 1980. The Canine as a Biomedical Research Model-
Immunological, Hematological, and Oncological Aspects. Washington, DC' US De-
partment of Energy. 425pp. " "

Stone D. M., P. B. Jacky, and D. J. Prieur. 1991. The Giemsa banding pattern of canine
chromosomes, using a cell synchronization technique. Genome 34-407-412

^/[r^ 1988 ' Ex P erimen ^ Surgery and Physiology: Induced

Animal Models of Human Disease. Baltimore: Williams & Wilkens. 350 pp
Teichner, M., K, Krumbacher, I. Doxiadis, G. Doxiadis, C. Fournel, D. Rigal J C Monier

Husbandry

This chapter provides guidelines for the care of laboratory dogs. The
first section, on housing, details design and construction considerations for
facilities that house dogs, as well as for primary enclosures (here defined as
cages and pens). The subsection on facilities contains information on build-
ings, rooms, and outside areas for containment of dogs, and that on environ-
ment and environmental control describes mechanisms for controlling the
environment and gives the legislatively mandated ranges for temperature,
humidity, and ventilation.

The remaining information in this chapter is supplemented by discus-
sions in other parts of this report. For example, Chapter 4 ("Management of
Breeding Colonies") contains sections on food for puppies and gestational
or lactating dams and on record-keeping for a breeding colony that amplify
the sections on food and identification and records in this chapter. Social-
ization of puppies is also discussed in Chapter 4. Modified primary enclo-
sures and bedding for dogs with specific disorders are described in Chapter
6 ("Special Considerations").

The 1985 amendment to the Animal Welfare Act required the U.S.
Department of Agriculture (USDA) to establish standards for exercise for
laboratory dogs, and they were established in 1991. A federal court has
now found that the regulations concerning exercise for dogs are inadequate
and ordered that new regulations be written. This committee has reviewed
the available information relevant to exercise, space, and well-being of dogs,

12 DOGS: LABORATORY ANIMAL MANAGEMENT

and it has found that, as was the case in 1985, it is inadequate to formulate
objective standards.

Although knowledge of canine behavior is leading to a consensus that
opportunities for social interaction with people, other dogs, or both are
important for promoting canine well-being, no similar consensus is avail-
able concerning fitness and exercise. Another issue is the notion that a
single standard can provide optimal care for all dogs. It is generally recog-
nized that such factors as breed, physical conformation, age, health status,
past experiences, and general behavioral characteristics influence what con-
stitutes adequate space and exercise. For example, a dog undergoing a
surgical procedure might require a restricted space to limit its activity. Once
the dog has recovered from the surgical procedure, a different space and
exercise regimen can be implemented. Likewise, the space and type and
duration of exercise required for Alaskan sled dogs in working condition is
quite different from that required for Shih Tzu and other brachycephalic
breeds. Finally, medical research benefits from the availability of dogs
with inherited disorders similar to those of humans, and the presence of
these disorders in dogs imposes the same types of restrictions that human
patients must endure. Unsupervised exercise is often contraindicated in
dogs with heart and metabolic diseases. Similarly, the construction and
layout of primary enclosures for dogs with such conditions as muscular
dystrophy, bleeding disorders, blindness, or Ehlers-Danlos syndrome must
be carefully considered to avoid compromising their health and well-being.

The most important objective for those responsible for housing dogs
should be to achieve an overall high level of care, rather than to conform
rigidly to specific standards. Animal well-being must be assessed case by
case by those qualified to do so. The regular evaluation of animal well-
being is an important aspect of any husbandry and animal-care program and
serves as a measure of the appropriateness of animal-care procedures. Pro-
cedures that are ultimately linked to the well-being of the individual are
defined as performance standards. The committee strongly recommends
that performance standards, coupled with sound professional judgment, be
used to develop space requirements and exercise programs for dogs. This
committee is firmly convinced that performance standards are ultimately
better for each dog's physical and behavioral well-being than engineering
standards, which might lack the flexiblity necessary to meet the needs of all
dogs.

HOUSING

Facilities

Housing facilities for dogs must be designed and constructed so that
they are structurally sound, protect animals from injury, contain animals

HUSBANDRY 13

securely, and prevent entry of other animals (9 CFR 3. la). Dog facilities
vary in size and complexity, depending on their purpose (e.g., holding or
breeding), colony size and type (e.g., specific-pathogen-free or conventional),
and breed. The design of breeding facilities should address the following:

The design should facilitate the conduct of research.

There should be sufficient space for expansion, both for adding ani-
mals and for increasing ancillary operations.

Breeding facilities should have sufficient space to house dams with
litters and the progeny.

The design should promote effective sanitation and husbandry proce-
dures.

Operation of the facility should be efficient and cost-effective.

Construction should be economical.

The physical facilities and equipment should be constructed and oper-
ated to fulfill the following criteria:

Contamination from areas adjacent to, but not part of, the facility
should be minimized. The locations of equipment washing and sterilizing,
food and bedding storage, quarantine, treatment, receiving and shipping,
shipping-crate storage, mechanical services, shops, offices, and laboratories
should minimize crossovers from soiled or contaminated to clean areas.
Clean material and equipment should not come into contact with soiled and
contaminated material and equipment.

There should be sufficient control of temperature, humidity, ventila-
tion, and lighting to provide the animals with appropriate conditions for
their comfort and well-being.

Behavioral well-being should be considered by allowing for visual
contact between dogs, social housing, exercise areas, and other appropriate
areas.

The entry of vermin should be prevented.

Provisions should be made for lunchrooms, locker rooms, and toilets
for animal-care personnel.

Caging equipment and feeding and watering devices should provide
a safe environment, make food and water readily available, minimize the
opportunity for transmission of diseases and parasites, and make sanitation
and sterilization efficient.

Auxiliary equipment such as washing machines, cage racks, rolling
equipment (e.g., dollies, tables, and carts), and fixed equipment (e.g., cabi-
nets, sinks, and shelving) should be designed, fabricated, and used to pro-
mote maximal sanitation and operating efficiency.

14 DOGS: LABORATORY ANIMAL MANAGEMENT

When a dog facility is designed to be part of a larger facility housing
other species of animals or part of a multipurpose building with offices and
research laboratories, the physical relationships between areas must be care-
fully planned (NRC, 1985a). Those establishing operating procedures should
use the best available information on physiology; nutrition; genetics; behav-
ior; animal breeding, care, and maintenance; colony management (produc-
tion and research); and disease control.

Dogs can be housed in indoor facilities, outdoor facilities, or a combi-
nation of the two (sheltered housing facilities). If the site is exclusively
indoors, the only factors that influence site selection are local zoning regu-
lations, the ability to control odors and noise, the availability of appropriate
utilities (e.g., sewerage and water) (9 CFR 3. Id), and the proximity to other
businesses. Indoor facilities should be constructed and maintained in com-
pliance with CFR, Title 9, Part 3.2 and the Guide (NRC, 1985a), as summa-
rized below.

Indoor Facilities

Walls. Exterior walls should be fire-resistant and impervious to ver-
min. To facilitate cleaning, interior walls should be smooth, hard, and
without pits or cracks, and they should be capable of withstanding the
impact of water under high pressure and scrubbing with cleaning agents
(e.g., detergents) and sanitizing agents (e.g., disinfectants). They should be
protected from damage caused by movable equipment.

Ceilings. Ceilings should be smooth, moistureproof, and free of imper-
fect junctions. Surface materials should be capable of withstanding scrub-
bing with detergents and disinfectants. Exposed pipes and fixtures are
undesirable.

Floors. Floors can be constructed of a variety of materials that are
smooth, moistureproof, nonabsorbent, and skidproof; that are resistant to
wear and the adverse effects of detergents, disinfectants, acid, and solvents;
and that are able to support heavy equipment without being gouged, cracked,
or pitted. They should also be easy to clean.

Drainage. Drainage must be adequate to allow rapid removal of water
(9 CFR 3. If). If floor drains are used, they should be constructed and
maintained in accordance with the Guide (NRC, 1985a). Rim flush drains
should be at least 6 in (15.2 cm) in diameter. Porous trap buckets installed
in the drains aid in cleaning and screen out solid waste. Floor drains must
contain traps that prevent backflow of sewage and gases (9 CFR 3. If). If

HUSBANDRY

unused floor drains are present, they should be closed with gaslight seals
that are flush with the floor surface.

Doors. All rooms should have doors. External doors should have
adequate latches and locks and should be verminproof when closed. If they
are left open during warm weather, adequate screening is essential. All
door frames should be sealed to walls and partitions with caulking com-
pound or a similar material.

Ports in animal-room doors allow personnel to observe the dogs with-
out entering the rooms, prevent injury to personnel while they are opening
doors, and provide a way to verify that room lights are on at appropriate
times. Experience has shown that doors at least 42 in (107 cm) wide and 84
in (213 cm) high allow free passage of cages and equipment. The doors
should be equipped with locks and kickplates and should be self-closing.

Outside windows. Outside windows and skylights might not be desir-
able, because they can contribute to unacceptable variations in temperature
and photoperiod. Other problems associated with outside windows and
skylights include dust and bacteria buildup on frames; drafts, and increased
ventilation costs.

Washrooms and sinks. Washing facilities for personnel (e.g., basins,
sinks, or showers) must be provided and must be readily accessible (9 CFR
3-lg).

Sheltered Housing Facilities

A sheltered housing facility, as defined by the Animal Welfare Regula-
tions (AWRs), is a facility that provides shelter, protection from the ele-
ments, and protection from temperature extremes at all times (9 CFR 1.1).
It can consist of runs or pens in a totally enclosed building or indoor-
outdoor runs with the indoor runs in a totally enclosed building. The re-
quirements for the sheltered portion of such facilities are identical with
those for indoor facilities, with the additional stipulation that the shelter
structure must be large enough to permit each animal to sit, stand, and lie
down in a normal manner and to turn around freely (9 CFR 3.3).

The outdoor portion of a sheltered housing facility should be constructed
to prevent the introduction of vermin. Outdoor floor areas in contact with
animals should be constructed of hard, moisture-resistant material and be
properly drained. The use of compacted earth, sand, gravel, or grass is
discouraged. The sides of runs can be constructed of chain-link fencing and
steel posts or pipe frames or, when necessary to prevent fighting or injury,
of solid concrete block coated with sealant. Fencing at the lower ends of

26 DOGS: LABORATORY ANIMAL MANAGEMENT

runs and pens should be high enough above the surface to permit adequate
drainage but not high enough to allow young puppies to escape. Curbs at
least 6 in (15.2 cm) high should be constructed between runs to help pre-
vent the spread of microorganisms during washing. Curbs 24-30 in (61.0-
76.2 cm) high might be necessary in runs in which the dog population is
constantly changing. Higher curbs might be beneficial in whelping-pen
runs to reduce the anxiety of nursing bitches. Run doors or gates should
have well-made latches that can be easily opened by animal-care personnel
but not by the dogs. Special consideration must be given to removing
animal wastes and controlling noise.

Outdoor Facilities

The AWRs, with some restrictions, permit facilities to house dogs solely
outdoors, provided that each animal has access to a structure (consisting of
a roof, four sides, and a floor) that furnishes adequate protection from cold,
heat, the direct rays of the sun, and the direct effects of wind, rain, and
snow (9 CFR 3.4). In general, this type of housing is discouraged for dogs
being used in an experimental protocol, because environmental factors, in-
fectious agents, and vermin are difficult to control. In other instances (e.g.,
in protocols requiring acclimation or in breeding colonies maintained in
temperate climates), outdoor facilities might be adequate.

Environment and Environmental Control

An important part of maintaining the health and well-being of labora-
tory animals is control of the environment. In nature, animals respond to
environmental changes both behaviorally and physiologically in a manner
that will maintain homeostasis. In an animal room, a behavioral response
might not be possible, and the animal must deal with an altered environ-
ment physiologically. Therefore, it is necessary to control the environment
to avoid physiologic changes. Besch (1985) has reviewed environmental
factors that can effect the biologic responses of laboratory animals.

Temperature and Humidity

Temperature and humidity are important considerations in a dog facility
(Besch, 1985). Dogs can tolerate moderate ranges of temperature and weather,
provided that they have appropriate amounts of food and water, have access
to shelter, and are allowed sufficient time to acclimate to their environment.
The Guide recommends that room temperature for dogs be maintained within
a range of 18-29C (64.4-84.2F) and relative humidity within a range of
30-70 percent. The AWRs require that the ambient temperature in indoor

HUSBANDRY 17

facilities not fall below 7.2C (45F) or rise above 29.4C (85F) for more
than 4 consecutive hours when dogs are present (9 CFR 3.2a). Except as
approved by the attending veterinarian, ambient temperature must not fall
below 10C (50F) for dogs not acclimated to lower temperatures, breeds
that cannot tolerate lower temperatures, and young, old, sick, or infirm dogs
(9 CFR 3.2a).

Dogs recovering from general anesthesia are frequently hypothermic.
Every attempt should be made to maintain normal body temperature during
surgery and recovery. This can be accomplished by using supplemental
sources of heat (e.g., heating pads and heat lamps), by avoiding direct
contact with heat-conducting surfaces (e.g., metal), and by maintaining the
postoperative recovery cage at 27-29C (80.6-84.2F) (NRC, 1985a). New-
born pups have poorly developed thermoregulatory mechanisms and might
require supplemental sources of heat. Temperatures of 29.4-32.2C (85-
90F) have been suggested for the first week of life (Poffenbarger et al.,
1990).

Each room should be provided with temperature controls and high- and
low-temperature alarms. Graphic recorders are useful for monitoring sys-
tem performance. Ideally, the temperature controls should allow individual
adjustments in dry-bulb temperature of 1C ( 2F) within the range of
18.3-29.4C (65-85F).

Relative humidity should be maintained at 30-70 percent throughout the
year (NRC, 1985a). It is important to control sources of humidity, such as
cage-cleaning equipment, transient loads from cleaning water (Gorton and
Besch, 1974), and thermal and mass loads from animals (Besch, 1991).
Low humidity can contribute to respiratory distress; and coughs, pneumonitis,
and other problems can follow. High humidity impairs efficient body-
cooling (Besch, 1991).

Ventilation

Ventilation serves multiple functions. It supplies oxygen; removes heat
generated by animals, lights, and equipment; dilutes gaseous contaminants;
and helps to control the effects of infiltration and exfiltration (Clough and
Gamble, 1976; Edwards et al., 1983). Gorton et ai. (1976) have reported a
method for estimating laboratory animal heat loads.

Indoor facilities must be sufficiently ventilated when dogs are present
to provide for their comfort and well-being and to minimize odors, ammo-
nia concentrations, drafts, and moisture condensation. Auxiliary ventilation
must be provided when the ambient temperature is 29.5C (85F) or higher
(9 CFR 3.2b). It is commonly thought that 10-15 volumetric changes per
hour with outside air must be provided to animal rooms and that air must
not be recirculated. As a consequence, animal facilities are generally venti-

18 DOGS: LABORATORY ANIMAL MANAGEMENT

lated with "one-pass" air, although the Guide (NRC, 1985a) includes provi-
sions for alternative methods of providing equal or more effective ventila-
tion. Besch (1992) has reviewed alternative methods of ventilation.

Ventilation system design and construction considerations include the
following:

Diffusers and exhaust openings should be located and controlled to
prevent drafts.

Outside openings and exhaust- ventilation grillework should be screened
to prevent entry of vermin. Screening should be cleaned regularly.

Air pressure in clean areas and animal rooms should be greater than
that in public and refuse areas. Where pathogenic organisms are present, a
negative-pressure system is necessary.

Ventilating mechanisms should be equipped with suitable alarm sys-
tems that will be activated if the temperature moves outside the desired
range or if power fails.

Supplemental exhaust fans or exhaust systems increase drying and
reduce humidity when fixed equipment is being washed. If such systems
are used, they should be permanently mounted in external windows or wall
openings, their frames should be sealed to the building structure, and the
systems should be screened.

Emergency power sources should be available in case of power fail-
ure.

Power and Lighting

Electric systems should be safe, furnish appropriate lighting, and pro-
vide a sufficient number of outlets. Lighting systems should allow for
either manual or timer-controlled changes in illumination levels or photope-
riods, and timer performance should be checked regularly. Lighting fix-
tures, switches, and outlets should be sealed to prevent entry or harboring
of vermin. Moistureproof switches and outlets should be installed where
water is used in cleaning. Emergency power should be available.

Illumination must be adequate and uniformly diffuse throughout each
animal room to allow proper cleaning and housekeeping, to permit inspec-
tion of animals, and to maintain the animals' well-being (9 CFR 3.2c).
Light levels of 323 Ix (30 ft-candles), measured 1.0 m (3.3 ft) above the
floor, appear to provide sufficient illumination for routine animal care (Bellhorn,
1980; NRC, 1985a). A regular diurnal lighting cycle must be provided (9
CFR 3.2c).

HUSBANDRY 19

Noise Control

Barking dogs can be a nuisance both to personnel working in animal
facilities and to the adjacent population. Self-generated noise of 80-1 10 dB
(Peterson, 1980; Sierens, 1976) has been measured in dog rooms. The
effects of noise on animals are reviewed in the Guide (NRC, 1985a).

Noise-control measures should be implemented in both indoor and out-
door environments. Sound transmission can be reduced by using concrete
to build walls, covering concrete walls with sound-attenuating material, and
eliminating windows (NRC, 1985a). Pekrul (1991) has discussed other
means of decreasing noise in animal facilities. Sound-attenuating materials
may be bonded to walls or ceilings only if they can be sanitized and will not
harbor vermin. Outdoor runs must be designed and constructed to comply
with local noise ordinances.

Chemicals and Toxic Substances

Many of the chemicals used in animal facilities for cleaning, sanitizing,
pest control, and other purposes can be toxic to housed animals and person-
nel. In addition, some materials used in construction for coating surfaces
can react with certain cleaning and sanitizing agents to produce toxic gases,
including chlorine. Where possible, the use of chemicals should be avoided.
For example, adequate ventilation is more effective than chemicals in elimi-
nating most animal-room odors, provided that air inlets are not placed near
the building exhaust. Newberne and Fox (1978) and Besch (1990) have
reviewed chemicals and other toxicants found in animal facilities.

Where chemical agents must be employed, it is essential to be familiar
with their potential toxicity and to develop procedures for using and dispos-
ing of them properly. Noxious chemicals should not be used to clean
animal facilities. Adequate rinsing is essential to prevent the skin irritation
or allergic reactions that can be caused by some cleaning and sanitizing
agents (e.g., pine oil).

Primary Enclosures

Primary enclosures should facilitate research while maintaining the health
and well-being of the dogs. They must confine dogs securely, enable them
to remain clean and dry, protect them from injury, and contain sufficient
space to allow them to sit, lie, stand, turn around, and walk normally (9
CFR 3.6a). The design should allow inspection of cage or pen occupants
without disturbing them and provide easy access to feeding and watering
devices for filling, changing, cleaning, and servicing.

20 DOGS: LABORATORY ANIMAL MANAGEMENT

Cages or pens should be fabricated of smooth, moisture-impervious,
corrosion-resistant materials that can be easily sanitized and sterilized. Floors
must be constructed to preclude entrapping toes, dew claws, or collars.
Expanded metal or plastic-covered metal mesh is satisfactory for pens or
runs, provided that the dogs' feet cannot pass through the openings (9 CFR
3.6a2x). Pen floors must have adequate drainage.

Each cage and pen should have a hinged or sliding door that covers the
opening sufficiently to prevent escape of the occupants. Each door should
have a latch that holds the door securely closed.

Space Recommendations

The AWRs require that the floor space for each dog equal at least the
"mathematical square of the sum of the length of the dog in inches (mea-
sured from the tip of its nose to the base of its tail) plus 6 inches [15.24
cm]," expressed in square feet (9 CFR 3.6cli). In addition, the interior
height of each enclosure must be "at least 6 inches [15.24 cm] higher than
the head of the tallest dog in the enclosure when it is in a normal standing
position" (9 CFR 3.6cliii). Each bitch with nursing pups must be given
additional floor space based on breed and behavioral characteristics and in
accordance with generally accepted husbandry practices, as determined by
the attending veterinarian (9 CFR 3.6clii). The additional space for each
nursing pup must be at least 5 percent of the minimum required for the
bitch, unless otherwise approved by the attending veterinarian (9 CFR 3.6clii).
Minimal space recommendations for dogs are also given in the Guide (NRC,
1985a, p. 14). These requirements and recommendations are based prima-
rily on professional judgment and convention.

The few scientific studies on this subject have focused on how enclo-
sure size affects movement, activity patterns, and physical fitness. Clark et
al. (1991) found no decreases in physical fitness, as measured by heart rate
and muscle enzyme (succinate dehydrogenase) activity, when dogs were
housed in cages or runs of various sizes that complied with federal stan-
dards and guidelines; however, modest decreases in fitness were found when
dogs were housed in cages smaller than mandated by the AWRs. It has
been shown that, in general, dogs are more active in pens and runs than in
cages; however, dogs housed in the largest enclosures are not always the
most active (Hetts et al., 1992; Kite et al., 1977; Hughes and Campbell,
1990; Hughes et al., 1989; Neamand et al., 1975). Enclosure size has not
been demonstrated to affect the musculoskeletal system (Newton, 1972),
cortisol concentrations (Campbell et al., 1988; Clark et al., 1991), or se-
lected measures of immune function (Campbell et al., 1988). Although they
provide interesting and relevant information, the studies do not provide

HUSBANDRY 21

sufficient objective, scientific data on which to base space requirements for
dogs.

To set standards based on scientific data, one must show a correlation
between cage size and behavioral well-being. That poses two problems: it
is not clear how to define and measure behavioral well-being, and the deter-
mination of well-being depends on human interpretations of the data. Move-
ment and activity patterns are unlikely to be sensitive behavioral measures,
because a dog's activity can be increased without improving its well-being
(e.g., if there is locomotor stereotypy or increased activity caused by social
isolation or competition for space). Moreover, the definition of movement
varies between studies, so it is difficult to compare and interpret results. It
is generally accepted that a variety of perspectives are needed to assess
well-being, including measures of physical health, of neuroendocrine and
immunologic responses to stress, of the ability to respond effectively to
social and nonsocial environments, and of behavior. Scientific data on dogs
are inadequate to support any such assessment relative to enclosure size.

EXERCISE AND ENVIRONMENTAL ENRICHMENT

The requirements for providing opportunities for dogs to exercise are
specified in the AWRs (9 CFR 3.8). The following paragraph summarizes
the AWRs now in effect. It is incumbent on the reader to keep abreast of
changes that might occur as the result of further federal court or USDA
actions.

Dogs over 12 weeks old, except bitches with litters, must be given the
opportunity for regular exercise if they are kept individually in cages, pens,
or runs that are less than 2 times the AWR-required floor space. Dogs
housed in groups do not require exercise periods, provided that the total
floor space of the cages, pens, or runs equals the sum of the AWR-required
spaces for the dogs if housed individually. If a dog is housed without
sensory contact with other dogs, it must receive positive physical contact
with humans at least once a day. Forced-exercise programs (e.g., swim-
ming or walking on treadmills or carousel devices) are not considered to
comply with the AWRs. Each institution is responsible for developing a
plan for providing exercise. The plan must be approved by the attending
veterinarian and must be made available to USDA on request. Exceptions
to the requirement for exercise can be made by the attending veterinarian
case by case or, if exercise is inappropriate for a scientific protocol, by the
institutional animal care and use committee (I AC UC). In the former in-
stance, the exemption from exercise must be reviewed every 30 days, unless
it was granted because of a permanent condition (9 CFR 3.8d). In the latter
instance, exemptions must be reviewed at appropriate intervals, as deter-
mined by the IACUC, but not less often than every 6 months (9 CFR 2.31)

22 DOGS: LABORATORY ANIMAL MANAGEMENT

Recent studies have provided some information on exercise and well-
being. Clark et al. (1991) and Hetts et al. (1992) found that 30 minutes of
forced treadmill exercise five times a week did not affect physical fitness or
behavior as measured in the study. Campbell et al. (1988) reported that
releasing dogs either singly or as a group into a large area for 35-minute
exercise periods three times a week did not affect cage activity patterns or
weekly measures of selected hematologic or serum biochemical values. How-
ever, dogs were more active during the release periods than in their cages,
and dogs released individually had different activity patterns from those of
dogs released in groups. Studies on enclosure size and exercise are cited in
the section above on space recommendations. Although the studies have
provided important and relevant information, sufficient data are still not
available to support definitive conclusions about the relationship between
exercise and well-being. Future studies should be based on larger samples,
use a variety of behavioral measures to evaluate well-being (activity pat-
terns are not likely to be sensitive indicators of well-being), and consider
the substantial individual variations in physiologic characteristics that have
been reported.

It is well known that dogs are highly social animals, and social isola-
tion and solitary housing are considered to be important stressors of social
species (Wolfle, 1990). Solitary housing has been shown to be associated
with less activity and with nonsocial repetitive behaviors (Hubrecht et al.,
1992). Hetts et al. (1992) have found that socially isolated dogs (i.e., dogs
having only auditory contact with other dogs and contact with people only
during routine husbandry procedures) display bizarre movement patterns
and tend to vocalize more than dogs that have more social contact. Several
studies have reported that dogs are more active in the presence of humans
(Campbell et al., 1988; Hetts et al., 1992; Hughes and Campbell, 1990;
Hughes et al., 1989), especially when human presence is relatively rare
(Hubrecht et al., 1992). It has also been shown that dogs housed in pairs
sleep more than dogs housed singly (Hetts et al., 1992). Although the
relationship between sleep patterns and well-being has not been studied in
dogs, there is evidence in other species that normal sleep can be disrupted
by a variety of environmental stressors and that return to normal sleep
patterns can be a sensitive indicator of an animal's adaptation to environ-
mental changes (Ruckenbusch, 1975).

Evidence of the importance of social interactions for dogs is strong
enough to support a recommendation that dogs be socially housed in com-
patible groups, be given opportunities for social interaction during the exer-
cise period, or both. The AWRs address the compatible grouping of dogs in
the same primary enclosure (9 CFR 3.7). Age, sex, experience, and genetic
differences in social behavior between individuals and breeds influence how
dogs accept social housing and respond to social interaction (Fuller, 1970;

HUSBANDRY 23

King, 1954; Scott and Fuller, 1965). Social interactions should minimize
fearful and aggressive behaviors.

Examples of plans that provide social interactions are leash walking
and release of dogs in an enclosed area for specified periods. In the latter,
several compatible dogs that are housed in the same room can be released
together; however, females in proestrus or estrus should not be released
with males. Exercise rooms should be cleaned and sanitized between uses
by dogs from separate rooms to minimize disease transmission. Only dogs
of similar microbiologic status should be combined in groups (see Chapter
5).

If dogs are to be group-released, the composition of the group should
remain as stable as possible (i.e., the members of the group should be the
same dogs each time), because how readily a group of dogs accepts new
members varies a great deal. Some dogs form closed social groups and
attack new members (King, 1954). Changes in group composition often
cause instability in the social dominance hierarchy, which in turn can result
in intraspecific aggression. It is important to remember that two dogs make
a pack, and the behavior of a pack is often very different from that of an
individual dog. A thorough understanding of pack structure and social
behavior is important for those managing research dogs. Any dog that is
being attacked or threatened by the group to the extent that it cannot move
about freely should be removed and given an alternative method of exer-
cise. Group-released dogs should be observed frequently during the exer-
cise period to ensure their safety.

Positive social interactions with humans can be achieved by having one
or more people in the room during the exercise period. There is evidence
that passive contact with a person is more reinforcing to dogs that have
been socially isolated than is active contact (Stanley, 1965; Stanley and
Elliot, 1962). If a dog displays fearful behavior when handled or petted, the
handler should sit passively, avoid eye contact, and allow the dog to ap-
proach at will. As fearful behavior decreases, contact can gradually become
more active.

Information on other types of environmental enrichment for dogs is
scarce. The need for complex or varied environments has not been studied.
Dogs have been observed to manipulate and direct attention to loose objects
they find in their enclosures (Hetts et al., 1992), and dogs provided with
toys spent an average of 24 percent of their time using them (Hubrecht,
1993). The toys reduced the dogs' inactive time and decreased destructive
behavior aimed at cage apparatuses (Hubrecht, 1993). The relevance of
these behavioral changes to well-being is not yet known. Nonetheless, such
devices as balls, chew toys, and ropes might be considered for dogs in
restricted environments. It is recommended that an ethologist, comparative
psychologist, or animal behaviorist knowledgeable about dog behavior be

24 DOGS: LABORATORY ANIMAL MANAGEMENT

consulted by those designing exercise and social interaction plans or when
other questions arise concerning the behavioral well-being of dogs.

FOOD

Selecting Optimal Rations

Many commercially available dog foods contain all essential nutrients
in their required proportions, as outlined in Nutrient Requirements of Dogs
(NRC, 1985b) and the Association of American Feed Control Officials'
Official Publication 1993 (AAFCO, 1993). These foods are manufactured
in dry, semimoist, and canned forms. Dogs should be fed only complete
and balanced diets. Specific procedures should be followed to ensure that
stored foods do not become deficient in nutrients (NRC, 1985a).

Diet quality can be evaluated by examining the label for a statement of
nutritional adequacy, which must be present on all dog-food products sold
across state lines. This statement informs the purchaser whether the prod-
uct has been approved for use as a complete ration for specified life stages
(i.e., growth, maintenance, or pregnancy and lactation). Approval is ob-
tained by one of the following means:

Each of the diet's individual ingredients is analyzed for all essential
nutrients; the sum of these nutrients in all ingredients must meet or exceed
the nutritional requirements of the animal for specified life stages.

The product itself is chemically analyzed and shown to meet or ex-
ceed the essential-nutrient requirements for specified life stages.

The product passes a feeding trial as specified by the Association of
American Feed Control Officials.

If the product fails to be approved, it must be labeled for use as a
dietary supplement only and is not appropriate for use as a dog food. Of the
three means of approval, only the feeding trial evaluates the availability of
the nutrients in the product. Dog foods approved by that method should be
used whenever possible. If such a diet cannot be used, because it would
interfere with the experimental design (e.g., nutritional studies with purified
diets), the manufacturer of the diet to be used should be consulted about
experience with the diet's performance under given conditions.

Many commercially available dog foods, although designed for a speci-
fied life stage, are approved and adequate for use during all life stages.
Most growth formulations will meet the requirements for gestation, lacta-
tion, and maintenance. Similarly, most gestation-lactation products also
meet requirements for growth and maintenance. Some foods intended for
maintenance will meet the criteria for more than one life stage. However,

HUSBANDRY 25

no food should be used for growth, gestation, and lactation unless its label
states that it meets or exceeds nutrient requirements for these life stages.

Special therapeutic diets are available for dogs with specific nutrient
requirements caused by the presence of disease (Kirk and Bonagura, 1992;
Lewis et al., 1987). Such diets should be fed only under the supervision of
a veterinarian.

Feeding

Most commercial rations are formulated to meet all nutrient require-
ments if a dog eats enough to fulfill its caloric requirements. Estimates of
daily caloric requirements can be obtained from several sources, including
the manufacturer of the specific food being used. These estimates can be
used to initiate feeding programs, but they might need substantial modifica-
tion because of variations in metabolic rates of individual dogs.

Under most kennel conditions, meal feeding is preferable to free-choice
feeding, and individual feeding is preferable to group feeding for the fol-
lowing reasons:

Restricted feeding has been shown to decrease the incidence of metabolic
bone disease in growing dogs that mature at greater than 30 Ib (Kealy et al.,
1992).

Restricted feeding has been shown to decrease the incidence of obe-
sity in young beagles and Labrador retrievers (Kendall and Burger, 1980).

The continual ingestion of small amounts of food observed in free-
choice feeding programs stimulates oral bacterial growth and might pro-
mote dental disease and gingivitis (Dr. John Saidla, Department of Clinical
Sciences, New York State College of Veterinary Medicine, Cornell Univer-
sity, Ithaca, N.Y., unpublished).

When dogs are fed in groups, dominant dogs might overeat and might
prevent subordinate dogs from eating enough to fulfill their daily needs.

When dogs are fed individually, their food intake can be monitored.

Some kennels have successfully used free-choice feeding to maintain
dogs. This practice is most successful when the diet used is a food of
relatively low energy density and palatability.

Dogs must be fed at least once a day, except as required for adequate
veterinary care (9 CFR 3.9a). Each healthy adult dog should be fed enough
to maintain its optimal body weight; this amount will vary with the environ-
ment and with the dog's age, sex, breed, temperament, and activity. Within
an individual breed, there is often a wide variety of normal sizes. It is
better to evaluate a dog's size according to how it looks and how it feels
than according to body weight alone. With the hands-on approach, a dog's

26 DOGS: LABORATORY ANIMAL MANAGEMENT

rib cage, spinous processes, and ileal wings should be easily palpable. They
should not protrude from under the skin, nor should they be buried under a
layer of adipose tissue. Once an adult dog is being maintained at its ideal
body size, its weight can be used as a reference for future evaluation of
food requirement. However, the loss of muscle mass and gain of adipose
tissue, such as are observed in several endocrine disorders, and shifts in
fluid balance might make body weight an inaccurate means of assessing
nutritional status; therefore, body weight should not completely replace ap-
pearance and feel as assessment methods.

Contaminants

Animal-colony managers should be judicious in purchasing, transport-
ing, storing, and handling food to ensure that it does not introduce diseases,
potential disease vectors, or parasites. Food must be stored in a manner that
prevents spoilage, contamination, and vermin infestation. Open bags must
be stored in leakproof containers with tightly fitting lids (9 CFR 3.1e; NRC,
1985a).

Contaminants in food can have dramatic effects on biochemical and
physiologic processes. In general, food for dogs should not be manufac-
tured or stored in facilities used for farm foods or any products containing
additives, such as rodenticides, insecticides, hormones, antibiotics, fumi-
gants, or other potential toxicants.

WATER

Ordinarily, all dogs should receive fresh, clean, potable water ad libi-
tum. If water is not continuously available, the AWRs require that it be
made available at least twice a day for at least 1 hour each time, unless it is
restricted by the attending veterinarian (9 CFR 3.10).

Watering devices can be either portable or self- watering. Self-watering
devices are convenient and reduce labor, but they require scheduled obser-
vations to ensure proper function. Portable watering devices should be
easily removable for daily rinsing and periodic sanitizing.

BEDDING AND RESTING APPARATUSES

Bedding can be used in some husbandry situations. For example, if
drains are not available, it can be used as an absorbent to help to keep dogs
clean and dry. Kinds of bedding typically used for dogs are wood shavings
and shredded paper. Bedding must be stored in a manner that protects it
from contamination and vermin infestation (9 CFR 3.1e). -

Resting apparatuses, especially those made of high-density polyethyl-

HUSBANDRY 27

ene (Britz, 1990), are useful for minimizing loss of body heat from dogs in
postoperative recovery, dogs in ill health, and young pups with poorly de-
veloped heat-control mechanisms.

SANITATION

The schedule for cleaning and disinfecting dog facilities will vary ac-
cording to the physical makeup of pens, cages, or runs and other factors.
Generally, primary enclosures should be cleaned as needed and sanitized at
least once every 2 weeks. Excrement pans and runs should be cleaned
daily. If pens and runs composed of materials that cannot be sanitized (e.g.,
gravel, sand, or pea stone) are used, the contaminated materials should be
replaced as often as necessary to prevent odors, diseases, and vermin infes-
tation. Procedures outlined in the AWRs (9 CFR 3.11) should be followed.
Dogs must be removed before the floors of primary enclosures are thor-
oughly cleaned. Primary enclosures containing bitches near parturition,
dams with litters, or dogs in quarantine require a cleaning schedule that
disturbs them as little as possible.

Equipment and peripheral areas should be cleaned according to the
recommendations of the Guide (NRC, 1985a). Waste should be removed
regularly and frequently, and safe, sanitary procedures should be used to
collect and discard it (NRC, 1985a).

IDENTIFICATION AND RECORDS

Identification

Each dog held in a research facility must be marked either with the
official USDA tag or tattoo that was on the dog at the time it was acquired
or with a tag, tattoo, or collar applied by the facility that individually iden-
tifies the dog by number (9 CFR 2.38gl).

Unweaned puppies need not be individually numbered as long as they
are maintained in the same primary enclosure as their dam (9 CFR 2.38g3).
However, they can be marked for identification with a variety of methods.
Colored yarns or spots made with such marking substances as nail polish or
paint provide a quick visual reference. Subcutaneous dots can be made by
injecting a small amount of tattoo ink beneath the abdominal skin with a
tuberculin syringe and 25-gauge needle. Ink dots should be placed in a
different location for each pup (e.g., left axilla and right side of abdomen).
The location or pattern of the dots and the sex and markings of each pup
provide individual identification until permanent tattoos can be applied.

Tattooing of the inner surface of a dog's ear is common. Before the
tattoo is applied, the ear should be cleaned thoroughly. Tattoos can be

28 DOGS: LABORATORY ANIMAL MANAGEMENT

applied with special pliers or an electrovibrator. A tattoo might have to be
reapplied after several years. An ancillary method for individually identify-
ing dogs uses a subcutaneously implanted, permanently encoded microchip
(transponder) that, when activated by an electronic scanner, broadcasts the
encoded number; the scanner transfers the broadcast to a processor that
produces either a digital readout or a printed copy. This identification
system can be useful during daily examination of dogs being used in stud-
ies, but it has not been approved by USDA as the sole source of identifica-
tion because there is no standard implantation site, no standardized scanner,
and no definitive information on whether the microchip migrates from the
implantation site. USDA has approved the trial use of the microchips for a
few commercial organizations (Richard L. Crawford, Assistant Deputy Ad-
ministrator for Animal Care, Regulatory Enforcement and Animal Care,
APHIS, USDA, Beltsville, Md., personal communication, 1993).

Record-Keeping

Record-Keeping for Scientists and Animal-Care Staff

A life-long, day-to-day log of individual events and experimental pro-
cedures experienced by each dog especially surgery, postsurgical analge-
sia, and other veterinary interventions should be carefully maintained. The
log will assist animal-care personnel in providing appropriate care, investi-
gators in interpreting research results, and the institution in preparing its
annual report to USDA (9 CFR 2.36). Computer programs for maintaining
such logs are commercially available (Riley and Blackford, 1991). For
small colonies, hand-kept records on each dog might be more appropriate.
McKelvie and Shultz (1964) described a record system for long-term stud-
ies that is still relevant; it covers clinical examination and includes a coded
daily log entry of all events that the animal has experienced.

Records Required by Federal Regulations

Research facilities are obliged to maintain records on procurement, transport,
and disposal of all dogs and an inventory of dogs in the facility. When dogs
are procured, facilities are required to obtain detailed information on the
seller including name, address, USDA license or registration number or
vehicle license number and state and a description of each dog (9 CFR
2.35b). Likewise, when a dog is transferred to another owner, records must
include the name and address of the purchaser, the date and method of
transport, and a certificate of health (9 CFR 2.35c). Additional information
is available in the section of this chapter entitled "Transportation."

A variety of forms are available to assist institutions in keeping records.

HUSBANDRY 29

Among them are USDA Interstate and International Certificate of Health
Examination for Small Animals (VS Form 18-1), Record of Dogs and Cats
on Hand (VS Form 18-5), and Record of Disposition of Dogs and Cats (VS
Form 18-6). These forms can be obtained from Regulatory Enforcement
and Animal Care, APHIS, USDA, Federal Building, Room 565, 6505 Belcrest
Road, Hyattsville, MD 20782 (telephone: 301-436-7833). All records should
be maintained for at least 3 years (9 CFR 2.35f).

Records must also be maintained on all offspring born to dogs in the
colony (9 CFR 2.35b) and on exceptions to the requirements for exercise (9
CFR 3.8d). Facilities conducting research on any vertebrate animal, includ-
ing dogs, are obliged to maintain additional records that include the follow-
ing:

minutes of meetings of the IACUC;

semiannual IACUC reports;

protocols involving animal use;

scientifically justified deviations from the AWRs; and

studies involving pain in which analgesics cannot be used.

Some of the information must be reported annually to USDA (9 CFR
2.36); other information, such as approved protocols, must be maintained
for 3 years after the study ends (9 CFR 2.35f).

EMERGENCY, WEEKEND, AND HOLIDAY CARE

Dogs should be observed and cared for by qualified personnel every
day, including weekends and holidays, as outlined in the Guide (NRC, 1985a).
Emergency veterinary care should be available after working hours and on
weekends and holidays. For dogs undergoing particular experimental pro-
cedures and dogs with conditions that might require emergency care, inves-
tigators should develop written protocols and provide appropriate additional
coverage.

TRANSPORTATION

Transportation over long distances is known to be a stressor for ani-
mals. Proper attention to environmental conditions, cage design, and care
in transit will minimize the stress. The AWRs specify the requirements for
transporting dogs (9 CFR 3.13-3.19). Before a dog is transported, special
arrangements must be made between the shipper (consignor), the carrier(s)
or intermediate handlers, and the recipient (consignee). The shipper must
certify that the dog was offered food and water during the 4 hours before
delivery to the carrier and must prepare a written certification, which must

30 DOGS: LABORATORY ANIMAL MANAGEMENT

be securely attached to the cage and must contain the shipper's name and
address, the animal identification number, the time and date when the dog
was last offered food and water, specific instructions for feeding and water-
ing the dog for a 24-hour period, and the signature of the shipper with the
date and time when the certification was signed.

Primary Enclosures

Carriers must not accept dogs for shipment if their primary enclosures
do not meet the requirements of the AWRs (9 CFR 3.14). The primary
enclosure must be large enough to allow a dog to turn around while stand-
ing, to stand and sit erect, and to lie in a natural position. Primary enclo-
sures must be structurally sound, free of internal protrusions that could
cause injury, constructed of nontoxic materials, and able to withstand the
normal rigors of transportation. The container must secure the animal and
all parts of its body inside the enclosure. Devices, such as handles, must be
attached to the outside to allow the container to be lifted without tilting.
The container must have a leakproof, solid floor or have a raised floor and a
leakproof collection tray. If animals are housed directly on the floor, absor-
bent bedding material must be provided. Primary enclosures must be cleaned
and any litter replaced if dogs are in transit for more than 24 hours. Pri-
mary enclosures should be well ventilated to minimize the potential for a
thermal gradient during shipment. Additional specifications for transport
cages are in the AWRs (9 CFR 3.14) and the I AT A Live Animal Regulations
(IATA, 1993 et seq.).

Puppies 4 months old or younger must not be transported in the same
primary enclosure with adult dogs other than their dams. For puppies shipped
during sensitive periods of behavioral development (i.e., 8-14 weeks of age;
see Scott and Fuller, 1965), shipping stress should be minimized. Dogs
likely to display aggressive behavior must be shipped individually, and
females in heat must not be transported in the same primary enclosures as
males. No more than two live puppies 8 weeks to 6 months old, of compa-
rable size, and weighing 9 kg (20 Ib) or less each may be transported by air
in the same primary enclosure. Older dogs and puppies weighing more than
9 kg (20 Ib) should be individually housed. Weaned littermates that are less
than 8 weeks old and are accompanied by their dam may be transported in
the same enclosure to research facilities, either by air or surface transport.
During transport by surface vehicle, no more than four dogs 8 weeks old or
older and of comparable size may be transported in the same primary enclo-
sure.

When viral-antibody-free (unvaccinated) dogs are transported between
facilities, precautions must be taken to avoid contact with infectious agents.
Some commercial suppliers have developed filtered shipping containers to

HUSBANDRY 31

transport those dogs. IATA rules require that special measures be taken to
ensure that ventilation rates are maintained within the container, that the
container be appropriately labeled, that sufficient water be provided for the
entire journey, and that food, if required, be provided at the point of origin
(IATA, 1993).

Environmental Conditions

At all times, containers holding dogs should be placed in climate-con-
trolled areas that provide protection from the elements (9 CFR 3.13, 3.15,
3.18-3.19). Trucks and planes must be ventilated and provide air that has
adequate oxygen and is free of harmful gases and paniculate contaminants.
Airlines should always place dogs in pressurized compartments. Dogs may
be shipped if temperatures will fall below 7.2C (45F) during any portion
of their journey only if a veterinarian certifies in writing that they have
been acclimated to lower temperatures and states the lowest temperature to
which they have been acclimated. During transit, dogs must not be exposed
to ambient temperatures exceeding 29.4C (85F) for a period of more than
4 hours.

Food and Water

All dogs must be offered food and water within 4 hours of delivery to
the carrier (9 CFR 3.13c). Carriers must offer water to each dog at 12-hour
intervals beginning 12 hours after the shipper last offered water. Adult
dogs must be fed at least once every 24 hours, and puppies less than 16
weeks old must be fed every 12 hours throughout the trip. Feeding and
watering utensils must be firmly secured to the inside of the container and
placed so that they can be filled from outside the container. Written in-
structions for feeding and watering in transit must be attached to the pri-
mary enclosure in such a way that they are easily seen and read (9 CFR
3.16).

Other Requirements

There are special requirements for animal holding areas of terminal
facilities, including rules for sanitization, pest control, ventilation, tempera-
ture control, and shelter from direct sunlight, rain, snow, and extreme heat
(9 CFR 3.18).

Each dog must be accompanied by a health certificate, issued by a
licensed veterinarian not more than 10 days before shipping, that states that
the dog is free of any infectious disease or physical abnormality that would
endanger it or other animals or pose a threat to public health. An exemp-

32 DOGS: LABORATORY ANIMAL MANAGEMENT

tion can be made by the secretary of USDA for individual animals shipped
to research facilities if the facilities require animals that are not elegible for
certification (9 CFR 2/78b). Instructions for the administration of drugs or
provision of other special care must be firmly attached to the outside of the
container (9 CFR 3.14h). A pregnant bitch should be accompanied by a
certificate, signed by a veterinarian, that states that there is no risk of birth
during transit (IATA, 1993).

Carriers and intermediate handlers must not accept dogs more than 4
hours before the scheduled departure (6 hours by special arrangement). An
attempt must be made to notify the recipient on arrival at the destination
and at least once every 6 hours thereafter (9 CFR 3.13f). During shipment
by surface transportation, the operator of the conveyance or someone ac-
companying the operator must observe the dogs at least once every 4 hours
to ascertain that they have sufficient air for normal breathing and are not in
distress and that the rules for ambient temperature and all other AWR re-
quirements are met. The same rules apply in air carriers if the animal cargo
area is accessible during flight. If it is not accessible, the carrier must
observe the dogs at loading and unloading. Dogs in physical distress must
receive veterinary care as soon as possible (9 CFR 3.17).

REFERENCES

AAFCO (Association of American Feed Control Officials), Canine Nutrition Expert Subcom-
mittee, Pet Food Committee. 1993. AAFCO nutrient profiles for dog foods. Pp. 92-99
in Official Publication 1993. Atlanta: Association of American Feed Control Officials.
Available from Charles P. Frank; AAFCO Treasurer; c/o Georgia Department of Agricul-
ture; Plant Food, Feed, and Grain Division; Capitol Square, Atlanta, GA 30334.

Bellhorn, R. W. 1980. Lighting in the animal environment. Lab. Anim. Sci. 30(2): 440-450.

Besch, E. L. 1985. Definition of laboratory animal environmental conditions. Pp. 297-315 in
Animal Stress, G. P. Moberg, ed. Bethesda, Md.: American Physiological Society.

Besch, E. L. 1990. Environmental variables and animal needs. Pp. 113-131 in The Experi-
mental Animal in Biomedical Research. Vol. I: A Survey of Scientific and Ethical
Issues for Investigators, B. E. Rollin and M. L. Kesel, eds. Boca Raton, Fla.: CRC Press.

Besch, E. L. 1991. Temperature and humidity control. Pp. 154-166 in Handbook of Facilities
Planning. Vol. 2: Laboratory Animal Facilities, T. Ruys, ed. New York: Von Nostrand
Reinhold.

Besch, E. L. 1992. Animal facility ventilation air quality and quantity. ASHRAE Trans.
98(pt. 2):239-246.

Blitz, W. E., Jr. 1990. Caging systems for dogs under the new standards of the Animal
Welfare Act. Pp. 48-50 in Canine Research Environment, J. A. Mench and L. Krulisch,
eds. Bethesda, Md.: Scientists Center for Animal Welfare. Available from SCAW, 4805
St. Elmo Avenue, Bethesda, MD 20814.

Campbell, S. A., H. C. Hughes, H. E. Griffin, M. S. Landi, and F. M. Mallon. 1988. Some
effects of limited exercise on purpose-bred beagles. Am. J. Vet. Res. 49:1,298-1,301,

Clark, J. D., J. P. Calpin, and R. B. Armstrong. 1991. Influence of type of enclosure on
exercise fitness of dogs. Am. J. Vet. Res. 52:1,024-1,028.

Clough, G., and M. R. Gamble. 1976. Laboratory Animal Houses. A Guide to the Design and

HUSBANDRY 33

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MD 20814.

Management of Breeding Colonies

REPRODUCTION

To maintain the breeding efficiency of a colony or to breed an impor-
tant individual dog successfully, staff must understand the unique reproduc-
tive characteristics of dogs. The biology of canine reproduction has been
extensively reviewed (Burke, 1986; Christiansen, 1984; Concannon, 1991;
Concannon and Lein, 1989; Concannon et al., 1989). Information on herita-
bility of physical and other characteristics of dogs, Mendelian genetics of
breeding, the incidence and characteristics of diseases that have a genetic
basis, and methods for demonstrating heritability is also available (Patterson,
1975; Patterson et al., 1989; Shultz, 1970; Willis, 1989).

Reproductive Cycle of the Bitch

Most bitches can become pregnant once or twice a year. Each ovarian
cycle consists of the following phases:

A follicular phase, or proestrus, during which there is progressive
vulval swelling and a serosanguineous (bloody) vaginal discharge. During
this period, which can last from 3 days to 3 weeks, the bitch's blood has
high concentrations of estrogen. The male will show interest, but he either
does not or is not allowed to mount.

A periovulatory period, or estrus, during which estrogen declines

36 DOGS: LABORATORY ANIMAL MANAGEMENT

and progesterone increases as the ovarian corpora lutea form. This period
is also the early luteal phase of the cycle. During estrus, which can last
from 3 days to 3 weeks, the bitch assumes a characteristic posture in the
presence of a male in which the rump is raised and there is a curvature of
the back (lordosis) and the tail is held to one side (flagging). The male is
allowed to mount, and copulation occurs.

A midluteal and late luteal phase or metestrus (either pregnant or
nonpregnant metestrus), which lasts about 2 months and during which se-
rum progesterone remains elevated above 1 ng/ml.

A period of weak ovarian activity, or anestrus, lasting 2-10 months,
in which progesterone concentration is low, and there is no evidence of
estrogen stimulation of the uterus or vulva.

In constant photoperiods of 12 hours of light and 12 hours of darkness
or 14 hours of light and 10 hours of darkness, estrous periods should occur
with equal incidence throughout the year. Possible effects of constant light
have not been studied. With natural circannual changes in photoperiod,
bitches come into estrus more frequently in winter and spring months than
in summer and autumn months. In most breeds, the interval between es-
trous periods averages 7-8 months. After the age of 8 years, however, the
interval between cycles begins to lengthen, reaching 12 months or longer by
the age of 12 years (Andersen and Simpson, 1973).

Successful breeding requires that observation of reproductive condi-
tions be given high priority, and staff must be able to recognize the start of
proestrus. A swollen vulva might not be obvious on a dark or long-haired
dog, and bitches often lick away the bloody discharge; therefore, the vulva
of each breeding bitch must be examined closely two or three times a week,
beginning 4 months after estrus.

Vaginal cytology can be useful for estimating the best time for breeding
(Concannon and DiGregorio, 1986; Hoist, 1986; Olson et al., 1984) and
predicting the time of whelping, which will be 55-60 days after a change in
the smear indicates late estrus. Vaginal smears in anestrus are nondescript,
with a few leukocytes and small epithelial cells. In early proestrus, smears
include a high proportion of rounded epithelial cells, erythrocytes, and sometimes
a few leukocytes. During midproestrus, there is an increasing percentage of
cornified (flakelike) epithelial cells but no leukocytes. All or nearly all
epithelial cells in the smear are cornified from 2-8 days before ovulation
until 4-9 days after ovulation, when these cells predictably and abruptly
decline. In early metestrus, cornified cells are replaced by rounded, smaller
superficial cells, and there is usually an influx of leukocytes. The metestrus
smear slowly regresses to the nondescript anestrus smear. Smears should
be taken from the anterior vagina. They should be obtained and prepared
carefully with saline-moistened swabs and should not be contaminated with

MANAGEMENT OF BREEDING COLONIES 37

vulval material. In the case of bitches that have had reproductive problems,
when a successful breeding is important, or both, more accurate predictions
can be made by monitoring the progesterone concentration in the serum or
plasma with an enzyme-linked immunosorbent assay (ELISA) kit (Bouchard
et al., 1991a; Hegstad and Johnston, 1992; Johnston and Romagnoli, 1991).
In this test, ovulation occurs a mean of 1-2 days after the initial rise in
progesterone, peak fertility a mean of 0-4 days after the initial rise, loss of
fertility 6-11 days after, implantation 18-20 days after, and parturition 63-
65 days after (Concannon, 1991).

Mating

Theoretically, it is sufficient to maintain one male for every 10-20
females; however, in practice this ratio might not be adequate, for several
reasons. First, a bitch in proestrus produces pheromones that will start
proestrus in other bitches in the colony, making it likely that several bitches
will be in estrus simultaneously. Because mating an individual male more
often than once each day can reduce its sperm output after 1 week (Amann,
1986), a greater ratio of males to females might be required to maintain
breeding efficiency. Second, except under special circumstances, such as
reproducing a disease model, breeding programs should conscientiously avoid
inbreeding, and it has been estimated that a ratio greater than two males for
each 10 females is needed to prevent an increase in the coefficient of in-
breeding (Shultz, 1970).

Natural Mating

Mating can be done naturally or by artificial insemination with fresh or
frozen and thawed semen. Provided that the male is healthy, it is not
necessary to take special precautions or to use medications to treat the
genitalia because the vagina is not a sterile environment. However, it is
important to ascertain that neither the dog nor the bitch has canine brucellosis,
a disease that seriously affects reproduction and is a zoonosis (see "Control
of Infectious Diseases" in Chapter 5). The bitch is usually taken to the stud
dog's pen or cage, because a dog will often ignore the bitch or spend an
inordinate amount of time scent-marking if he is moved to new surround-
ings. The bitch should be mated on 2 or 3 days over a 3- to 5-day period.
Unless the staff is experienced in distinguishing early proestrus from estrus,
the bitch should be presented to the male for 10-15 minutes every day or
every other day from the time she is found to be in proestrus until she is
mated. Breeding pairs should not be left unattended, because some bitches
are highly selective in choosing mates and it is not uncommon for a bitch to
attack a dog that is not of her choosing. In addition, the dog might need

38 DOGS: LABORATORY ANIMAL MANAGEMENT

assistance until he attains a copulatory lock. Mating should be recorded
only on the basis of observations of copulatory locks that last several min-
utes or more. If a bitch refuses a particular dog, even when signs of estrus
(lordosis and flagging) are present, placing her with a different dog might
solve the problem. If it is important to the breeding program that a bitch be
bred to a dog that she is refusing, a caretaker should restrain her in a
manner that will prevent her biting either the caretaker or the stud dog
during breeding, or artificial insemination (AI) should be used.

To ensure accuracy of parentage, the same stud must be used for every
breeding within a single estrus to avoid multiple-sire litters. Bitches allow
dogs to mate from several days before ovulation until several days after
ovulation. Because the events of pregnancy are related to the time of
ovulation not necessarily to the time of mating parturition can occur 56-
68 days after a single mating and up to 70 days after the first of multiple
matings. Sperm can survive 6 days or more in the bitch, and ovulated eggs
can remain fertile for 3-7 days. Parturition should occur 62, 63, or 64 days
after ovulation in nearly every bitch (Concannon et al., 1983). Bitches that
whelp 56-60 days after the first mating often have small litters, probably
because they were bred at the end of the fertile period (P. Concannon, New
York State College of Veterinary Medicine, Cornell University, Ithaca, N.
Y., unpublished).

Artificial Insemination

AI can be helpful when males cannot be moved easily within or be-
tween facilities, when breeding females with weak or selective estrus be-
havior, when using males that cannot provide natural service, and for pre-
serving valuable animal models. Semen collection, handling of semen, and
insemination are described in detail elsewhere (Christiansen, 1984; Concannon
andBattista, 1989).

Insemination with fresh semen. Semen can be collected in a clean
paper cup or in a latex cone (artificial vagina) attached to a 15-ml conical
polypropylene centrifuge tube. An advantage of the former method is that
debris from the penis is less likely to become mixed in the ejaculate. Ejacu-
late should be maintained at room or skin temperature and should be checked
microscopically for sperm viability and malformations. Any variation from
the expected chalky white color or 1- to 5-cc volume should be recorded.
The full ejaculate should be deposited into the anterior vagina with a clean
plastic pipet attached to a syringe with nonrubber (e.g., polypropylene)
tubing. The hindquarters of the bitch should be raised for 10 minutes while
the vagina is manipulated digitally by an attendant wearing a clean glove.
The bitch should not be allowed to sit for 20 minutes, and pressure on her

MANAGEMENT OF BREEDING COLONIES

abdomen should be avoided. AI should be performed every other day until
two or three inseminations have been accomplished. The precise timing for
performing AI can be predicted by checking for softening of the vulva,
which often occurs around the time of ovulation; by demonstrating the
appropriate vaginal cytologic characteristics of advanced estrus; or by mea-
suring the initial rise in serum or plasma progesterone. Ideally, two insemi-
nations should occur before vaginal smears show reduced cornification.

Insemination with fresh chilled semen. Fresh semen can be diluted or
extended in one of several laboratory buffers or commercial extenders and
shipped refrigerated by overnight express for use in insemination in another
location (Concannon and Battista, 1989). At 4C (39.2F), sperm motility
remains nearly normal for 3-4 days if the semen is diluted in an appropriate
diluent and for 1 day if undiluted (see Morton and Bruce, 1989).

Insemination with frozen semen. Frozen semen should be thawed and
handled according to the instructions provided by the laboratory that pro-
cessed it, because each freezing technique has stringent requirements for
rate of thawing, dilution, and site of deposition. Although sperm live for
several days in fresh semen, they normally die within a few hours-; after
thawing; therefore, precise timing of insemination is important for success-
ful impregnation. The best time to inseminate is usually shortly after oo-
cyte maturation, which occurs 5-6 days after the initial rise in progesterone,
around the time of a surge in leutinizing hormone. In most bitches, the
inseminations should also take place 2-4 days before the decrease in vaginal
cornification. Reported success rates for vaginal insemination range from
to 70 percent (Concannon and Battista, 1989); success probably depends
heavily on the freezing method and the number of viable sperm insemi-
nated. Success rates of 50-90 percent have been reported for uterine in-
semination, which is accomplished surgically or with special instrumenta-
tion to deposit sperm through the cervix (Concannon and Battista, 1989).

Pregnancy and Parturition

Pregnancy can be determined at 25 days after ovulation by ultrasonography,
at 20-35 days after ovulation with palpation, and at 45 days after ovulation
with radiography (Johnson, 1986; Yeager and Concannon, 1990). There are
no well-documented biochemical or immunologic canine pregnancy tests
available. Concannon (1991) has reviewed changes in body weight during
pregnancy and pregnancy-specific changes in hematocrit, serum chemistry,
and metabolism.

Whelping facilities should provide seclusion from excessive noise and
other disturbances. The whelping box should be large enough to accommo-

40 DOGS: LABORATORY ANIMAL MANAGEMENT

date the bitch and pups and have sides high enough to prevent neonates
from wandering out of the box. The bottom of a large, fiberglass shipping
crate works well for beagle-size dogs. The whelping box should be pro-
vided about a week before expected parturition.

Johnson (1986) has reviewed the management of the pregnant bitch. A
nonpurulent green discharge, anorexia, and restlessness are normal just be-
fore parturition. Birth of a litter can be either rapid or protracted over much
of a day. Intervals between pups normally range from 20 minutes to 3
hours. Intervals greater than 3 hours can indicate a problem with fetal
position or uterine function and warrant veterinary attention. Persistent,
unproductive labor of more than 1 hour also requires veterinary attention
(Johnston and Romagnoli, 1991; Jones and Joshua, 1988).

NEONATAL CARE

Newborn pups, like all neonatal mammals, have poorly developed tem-
perature-control mechanisms; therefore, it is necessary to keep the tempera-
ture in the whelping box higher than room temperature. Temperatures of
29.4-32.2C (85-90F) have been suggested for the first 7 days of life,
26.7C (80F) for days 8-28, 21.1-23.9C (70-75F) for days 29-35, and
23.9C (70F) thereafter (Poffenbarger et al., 1990). That can be done by
raising the temperature of the room and placing insulation between the
whelping box and the cage or floor or by using heating devices, such as heat
lamps or built-in heating elements. However, caution is necessary in using
such heating devices; because pups younger than 7 days old have very slow
withdrawal reflexes (Breazile, 1978), they can be overheated or severely
burned by these devices. Circulating-water heating pads or commercial pig
warmers are useful, because they maintain heat at a safe level.

Whelping boxes should be examined two or more times a day for evi-
dence of maternal neglect or cannibalism and for problems with the pups.
A normal pup is plump and round, its head is mobile, and it exhibits a
rooting reflex. Breathing is regular and unlabored, and the coat is shiny and
free of debris. Abdominal enlargement after nursing is normal, but abdomi-
nal enlargement accompanied by restlessness, weakness, and either exces-
sive vocalization or complete silence can indicate illness or aerophagia.
Failure to gain weight is often the first sign of illness in a newborn animal
(Greco and Walters, 1990). Andersen (1970) reported expected weight
gains for beagle pups.

Dead pups should be removed from the box. Andersen (1970) and
Lawler (1989) have reviewed causes of neonatal deaths and have reported
an average rate of death of about 20 percent. Necropsy examination is
suggested for all pups that die or are euthanatized with severe illness. Such
examinations are necessary to distinguish between congenital defects, which
affect only the pups in which they occur; infectious diseases, whose spread

MANAGEMENT OF BREEDING COLONIES 4 1

might be prevented; and problems with the dam (e.g., insufficient milk) or
the environment (e.g., room temperature too low), which can be corrected.

REPRODUCTIVE PROBLEMS

False Estrus and Anestrus

Recurrent frequent false estrus (estrus without ovulation) has been re-
ported (Shille et al., 1984). In false estrus, estrus appears normal, and
bitches will mate but fail to conceive. False estrus can be confirmed by
demonstrating with a progesterone ELISA kit that the serum or plasma
progesterone concentration has not risen above 1 ng/ml, as would be ex-
pected for 50 days or more after ovulation if estrus were normal. Bitches
that often have false estrus or have false estrus followed in a few weeks by
normal estrus cause problems in maintaining breeding colonies. Except in
special circumstances, such as reproducing a disease model, it is preferable
to cull these animals. Culling based on small litter size, problems with
whelping or maternal behavior, chronic infertility, or persistent anestrus is
also appropriate. Methods for assessment and treatment for potential causes
of infertility in females have been extensively reviewed (Feldman and Nelson,
1987; Johnston and Romagnoli, 1991; Shille, 1986). Persistent anestrus can
be distinguished from unobserved cycles only through extremely careful
examinations for signs of proestrus or progesterone assays every 6 weeks.
Estradiol assays are not particularly informative, and assays of canine go-
nadotropin to diagnose primary gonadal failure are not readily available.
Attempts to induce estrus in anestrus bitches have had variable success
(Bouchard et al., 1991b; Concannon, 1992; Concannon et al. t 1989).

Delayed Parturition

Whelping should not be considered overdue until 67 days after the last
mating or possibly 70 or more days after the first of several matings. Ce-
sarean section should not be contemplated earlier unless there are obvious
signs of distress in the bitch. Johnson (1986) and Jones and Joshua (1988)
have reviewed veterinary management of dyvStocia.

Pseudopregnancy

Bitches that are not bred or that are bred but fail to become pregnant
frequently exhibit pseudopregnancy because of the progesterone secretion
that always follows ovulation. Signs of pseudopregnancy include extensive
mammary development, lactation, and maternal behavior. Pseudopregnancy
is rare in beagles but more common in other breeds. It is self-limiting and
usually does not require intervention (Feldman and Nelson, 1987).

42 DOGS: LABORATORY ANIMAL MANAGEMENT

SPECIAL NUTRITIONAL REQUIREMENTS

Bitches

During pregnancy and lactation, bitches should be fed a diet approved
by the Association of American Feed Control Officials for all life stages or
a diet specially formulated for gestation and lactation (see "Selecting Opti-
mal Rations" in Chapter 3). When a quality diet is fed, supplementation
with vitamins and minerals is neither necessary nor desirable.

During the first two-thirds of pregnancy, the amount fed should be the
same as that fed before pregnancy. During the last trimester, food intake
should be gradually increased so that at parturition it is 150 percent of the
daily maintenance requirement. Bitches should not be permitted to become
obese during gestation, because this condition can increase the risk of dystocia
and postparturient metabolic disorders (Johnston, 1986). Bitches that are
underfed during gestation tend to have a higher incidence of stillbirths than
bitches that are fed appropriate amounts, and their pups often weigh less at
birth (Holme, 1982).

Lactation represents the greatest nutrient challenge that bitches experi-
ence during their lifetimes. For the first 3 weeks after parturition, nutrient
requirements increase rapidly, leveling off at 200-250 percent of daily mainten-
ance requirements, or even more, depending on the number of nursing pups
(NRC, 1985). The nutritional demands of lactation are met best through
free access to both food and water. At the time of weaning, food is gener-
ally withheld for 24 hours to decrease milk production. Food intake for the
first day after weaning should be one-fourth of the amount required for
maintenance and then gradually increased to the maintenance requirement
by day 4. Ideally, lactating bitches should be within 15 percent of their
prebreeding body weight at the time of weaning (AAFCO, 1993).

Pups

Pups should be maintained exclusively on their dams' milk until they
are 3 weeks old. They can then begin to eat small amounts of a moistened
gestation-lactation diet or a growth diet. Most pups can be weaned com-
pletely onto this type of diet by the age of 6-8 weeks. For the development
of normal social behavior, it is desirable that they not be completely weaned
before they are 6 weeks old. Pups that cannot be nursed by their dam or a
foster dam before they are 5 weeks old should be fed one of the commer-
cially available, complete milk replacers. Pups can be fed with bottles and
nipples or stomach tubes. Bottles and nipples should be thoroughly cleaned
after each use. If a stomach tube is used, its proper placement can be

MANAGEMENT OF BREEDING COLONIES 43

ensured by inserting it to a distance equal to the premeasured distance from
the mouth to the last rib. A small amount of sterile saline solution should
be introduced through the tube before milk replacer is injected. After each
meal, orphaned pups should be massaged in the anal-genital region with a
warm, wet cotton ball to stimulate urination and defecation. Most orphans
can be completely weaned onto solid food by 5 weeks of age.

Young pups most readily eat canned or moistened dry food; older pups
can be fed dry, semi-moist, or canned food. Pups can be fed on either a
free-choice or meal-feeding program. If a meal-feeding program is used,
they should be fed at least four times a day until they are 3 months old,
three times a day until they reach two-thirds of their adult weight, and two
times a day thereafter. After the age of 3 months, free-choice programs can
lead to obesity in small breeds and faster than optimal growth in large
breeds. Excessively rapid growth in breeds whose weight at maturity is
more than 30 Ib has been associated with an increase in the incidence of
several metabolic bone diseases (Hedhammer, 1981; Hedhammer et al., 1974;
Kealy et al., 1992). Pups should be fed so that they grow at near optimal
rates; growth-curve data are often available from pet-food manufacturers.
When an appropriate growth ration is fed, no supplementation is necessary.
If a product is not capable of supporting an optimal growth rate, it is gener-
ally safer, less expensive, and more convenient to switch to a better-quality
growth diet. As a general rule, pups gain approximately 1-2 g/day per
pound of anticipated adult body weight (Lewis et al., 1987). An inappropri-
ate growth rate usually reflects a problem with the ration being fed or with
the pups' access to it.

VACCINATION AND DEWORMINO

Annual vaccinations and deworming of brood bitches should be sched-
uled for anestrus or weaning periods, not when bitches are in proestrus or
are pregnant.

Pups that have nursed on colostrum during the first 12 hours after birth
have received passive immunity to viruses against which the dam was im-
munized. If pups cannot nurse on colostrum, 16 ml of pooled serum admin-
istered subcutancously has been shown to be a successful alternative (Bouchard
et al., 1992), Maternally acquired immunity declines over time, and the rate
of decline, although variable, depends on the level of the dam's immunity at
parturition and the amount of colostrum ingested by each pup. About 30-50
percent of pups will be susceptible to disease and capable of being effec-
tively vaccinated by the age of 6-7 weeks. Most pups (more than 95 per-
cent) can be effectively vaccinated by the age of 16 weeks. General prin-
ciples of immunity in newborn animals and of immunoprophylaxis are reviewed
elsewhere (Carmiehael, 1983; Tizard, 1977a,b). Diseases to which pups are

44 DOGS: LABORATORY ANIMAL MANAGEMENT

susceptible and vaccination schedules are discussed in Chapter 5, Veteri-
nary Care.

Roundworms (Toxocara canis) and hookworms (Ancylostoma caninum
and A. braziliense) are endoparasites that commonly infect young pups.
Roundworms are typically transmitted from bitches to pups in utero, and
pups begin to shed eggs in their feces 3 weeks after birth. Pups infected
with hookworm larvae in their dams' milk typically begin to pass eggs in
their feces 2 weeks after birth. It is important that pups receive treatment
early in life if infection with roundworms or hookworms is suspected. To
prevent peracute hookworm disease in unweaned pups of bitches harboring
large numbers of somatic larvae, it might be necessary to treat the pups
before hookworm eggs are detectable in fecal examinations. Canine en-
doparasites are reviewed in Chapter 5 and discussed fully elsewhere (Georgi
and Georgi, 1992).

SOCIALIZATION OF PUPS

There is ample evidence of the importance of adequate socialization for
the normal behavioral development of dogs (Clarke et al., 1951; Fox, 1968;
Freedman et al., 1961; Houpt, 1991; Scott and Fuller, 1965). The term
socialization is somewhat confusing because it has been used to describe
events, processes, and procedures. In the narrowest sense, socialization is
the development of the primary social attachments that form between a pup,
its dam, and its littermates during a critical or sensitive period in its behav-
ioral development (Scott, 1968). The process is not peculiar to dogs but
occurs in many species of social mammals (see, for example, Cairns, 1966;
Harlow and Harlow, 1969). In a broader sense, socialization is the process
by which pups form attachments to other dogs, people, and environments.
Attachment formation might require nothing more than sufficient exposure
to or experience with other dogs, people, and elements of the environment,
which results in familiarity with a variety of stimuli (Cairns, 1966; Scott,
1963). Breeds and individual pups differ in ease of socialization (Scott,
1970). In any case, adequate socialization allows a pup to develop normal
social relationships with other dogs and to adapt to pair or group housing,
to adjust more easily to unfamiliar stimuli and environmental changes, and
to accept handling with little or no fear and distress (Scott, 1980).

Sensitive Period for Socialization

There is a sensitive period for socialization during which attachments
form most readily and rapidly (Scott and Fuller, 1965). The beginning of
the period is marked by the startle response to sound at the age of approxi-
mately 3 weeks. Also at 3 weeks, a pup begins to display distress vocaliza-

MANAGEMENT OF BREEDING COLONIES 45

tions when separated from its dam. Distress vocalizations are distinct from
those made in response to fear (Davis et al., 1977), hunger (Compton and
Scott, 1971; Scott and Bronson, 1964), or physical discomfort (Gurski et
al., 1980). Separation distress is greater in an unfamiliar pen (Elliot and
Scott, 1961). To minimize separation distress, pups should remain with
their dams for at least their first 6 weeks.

Ease of attachment formation varies between breeds and individuals but
generally peaks between the age of 6-8 weeks (Scott and Bronson, 1964).
Although socialization probably occurs at a low rate throughout life, the
end of the sensitive period is marked by the pup's increasing fear of the
unfamiliar at the age of 12-14 weeks (Scott, 1962).

Consequences of Inadequate Socialization

Pups that are inadequately socialized during the sensitive period exhibit
abnormal behaviors, called kennel-dog or isolation syndromes, that are char-
acterized by one or more of the following behaviors: generalized fearful-
ness, fear-motivated aggression, timidity, immobility, or hyperactivity (Scott
et al., 1967). Dogs that, as a result of inadequate socialization, become
highly distressed when subjected to common laboratory procedures (e.g.,
handling, walking on a leash, restraint, venipuncture, moves to different
enclosures, and contact with other dogs) probably do not make good re-
search subjects and might be in a compromised state of well-being. It has
been reported that physiologic measurements on such dogs can fall outside
normal limits (Vanderlip et al., 1985b).

Socialization Programs

Providing contact and handling only during routine husbandry proce-
dures might not be sufficient to produce behaviorally normal, cooperative
research animals (Vanderlip et al., 1985a,b). Specific programs that ad-
dress each aspect of socialization to dogs, to people, and to the environ-
ment should be implemented. Programs that can be used as examples for
providing adequate socialization have been reported (Vanderlip et ah, 1985a,b;
Wolfle, 1990).

The following are examples of elements that might be included in so-
cialization programs: positive contacts with more than one person, opportu-
nities to follow handlers, introduction to some type of restraint (e.g., a
collar and leash), contacts with conspecifics other than littermates, and op-
portunities to explore outside the kennel. Exploration might include expo-
sure to floors of different textures, to a room with different lighting, to
stairs, and to such equipment as exam tables, clippers, and scales. Expo-
sures to those elements should be gradual and paired with positive reinforc-

46 DOGS: LABORATORY ANIMAL MANAGEMENT

ers, such as food, petting, or verbal praise. Negative reinforcement and
physical punishment can elicit aggressive or fearful behaviors and will make
pups more difficult to handle. It is not necessary, or practical, to introduce
pups to every type of environment, person, or animal to which they will
later be exposed in order to provide adequate socialization. Evidence sug-
gests that experience in coping successfully with change facilitates later
success (Scott, 1980). Thus, the adequacy of any socialization program can
be determined by the ability of pups to adapt successfully to environmental
changes with minimal behavioral and physiologic disruption.

RECORD KEEPING

Records on colony reproduction are essential. Individual records should
contain the following minimal information on each bitch:

start date of each proestrus;

dates of mating and stud dog's identification number;

date on which bitch's diet should be increased (day 42 of gestation),
date to move bitch to whelping facility (day 50), and range of expected
whelping dates;

actual whelping date, whelping complications, number and sex of
live pups, number of stillbirths, and any obvious abnormalities in the pups;

date to start weaning, bitch's distemper antibody titer (if known),
and dates to deworm and vaccinate litter; and

date(s) and details of disposition of litter.

In addition, missed cycles, abortions, or any abnormal maternal behavior
should be recorded.

To facilitate review of the reproduction records of an entire colony, it is
helpful to have a separate computerized or manual-entry spreadsheet that
displays every reproductive cycle of each bitch in the colony. The spread-
sheet is most useful if it lists the following information, organized chrono-
logically by date of proestrus:

identification number of each bitch whose proestrus was first ob-
served on that date;

for each bitch bred, identification number of stud dog, first and last
dates of mating, total number of matings, and calculated or expected dates
for medical examinations, moving to whelping facility, and whelping; and

expected date of next cycle.

The spreadsheet should be updated periodically to include for each bitch the
actual whelping date; the length of gestation; litter information, as described

MANAGEMENT OF BREEDING COLONIES 4 j

above; the actual date of the next cycle; and the calculated interestrus inter-
val. A computerized list can be sorted to review the breeding records of
individual bitches and males over several years. Such a list also allows
examination for trends in low fertility, long or short gestation lengths as
indicators of poorly timed inseminations, number of matings per cycle, pro-
jected periods during which several bitches will be in heat at the same time
or no bitches will be in heat, and other matters that could reflect husbandry
management, or staff problems that need correction.

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MANAGEMENT OF BREEDING COLONIES 49

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Veterinary Care

Veterinary care in laboratory animal facilities goes beyond the preven-
tion, diagnosis, treatment, and control of disease. It also includes monitor-
ing animal care and welfare and providing guidance to investigators on
handling and immobilizing animals and preventing or reducing their pain
and distress (NRC, 1985, 1992). Responsibilities of the attending veterinar-
ian are specified by the Animal Welfare Regulations (9 CFR 2.33, research
facilities; 9 CFR 2.40, dealers and exhibitors).

The first sections of this chapter deal with the procurement and condi-
tioning of research dogs and the control of infectious and parasitic diseases.
Aspects of veterinary care dealing with the use of anesthetics and analge-
sics, surgery and postsurgical care, and euthanasia are taken up in the last
three sections. The medical aspects of reproductive disorders are discussed
in Chapter 4; special care for pups is also reviewed in Chapter 4 and ad-
dressed in detail elsewhere (Hoskins, 1990). Reference values for blood
analytes can be found in textbooks by Kaneko (1989) and Loeb and Quimby
(1989).

Dogs can be afflicted with many uncommonly occurring but scientifi-
cally interesting diseases and disorders, many of which also afflict humans.
Some breeds have predispositions to particular diseases and disorders (e.g.,
dalmatians are prone to urate bladder stones); a comprehensive review of
this subject is available (Willis, 1989). Chapter 6 of this book addresses the
maintenance of dogs with selected genetic disorders.

52 DOGS: LABORATORY ANIMAL MANAGEMENT

PROCUREMENT

General Considerations

Dogs acquired from outside a research facility's breeding program must
be obtained lawfully from dealers licensed by the U.S. Department of Agri-
culture (USDA) or sources that the USDA has exempted from licensing (7
USC 2137). A List of Licensed Dealers can be obtained from Regulatory
Enforcement and Animal Care, Animal and Plant Health Inspection Service,
USDA, Federal Building, Room 268, 6505 Belcrest Road, Hyattsville, MD
20782. Examples of exempt sources are municipal pounds and people who
provide dogs without compensation.

Procurement of dogs for research requires planning by a knowledgeable
person to ensure that the dogs receive good care and that the needs of the
investigator are met. The person should be familiar with federal regulations
applicable to the acquisition of dogs (9 CFR, parts 2 and 3) and with state
and local ordinances applicable to the aquisition of dogs from pounds and
shelters. It is strongly recommended that institutions inspect vendors' pre-
mises for compliance with procurement specifications agreed on by contract
before the first dogs are purchased and periodically thereafter.

Sources

Both random-source and purpose-bred dogs can be purchased for re-
search purposes. Random-source dogs are those raised under unknown
conditions of breeding and health. Sometimes they are stabilized and con-
ditioned (see below) by the dealer before sale. Purpose-bred dogs are those
from known matings that have limited exposure to infectious diseases.

Random-source dogs that have not been stabilized and conditioned by
the vendor (often called nonconditioned random-source dogs) are usually
acquired from USDA-licensed dealers or, less commonly, from pounds. If a
number of dogs of similar weight or body conformation are needed, the
purchaser must allow sufficient time for the group to be assembled by the
vendor. Random-source dogs that have been stabilized and conditioned
(often called conditioned random-source dogs) should be purchased only
from vendors that have written standard procedures for their conditioning
programs. Purpose-bred dogs are acquired from USDA-licensed dealers
that breed dogs specifically for research or from an institutional breeding
program. Dogs with diseases of research interest are often acquired from
exempt sources, such as pet owners referred by clinical veterinarians.

VETERINARY CARE JJ

Conditioning

Conditioning is defined as physiologic and behavioral adjustment to a
new environment. The period required for that adjustment to occur is called
the conditioning period. Conditioning consists of adjustment to a new regi-
men, including new people, diet, climate, and exercise. The adjustment can
be hastened if the using institution provides the same type of food as the
dealer or vendor and uses the same type of automatic watering devices.
Physiologic status, as well as the presence of diseases, can be determined
by assessing red-cell counts, packed-cell volumes, and white-cell differen-
tial counts and by using blood urea nitrogen tests and other examinations of
blood and urine. Those tests are most valuable when samples are taken
several days after arrival, by which time initial adjustments to the new
environment have been made. Abnormal findings on any of the tests might
warrant followup examinations.

Evidence of behavioral adjustment includes decreases in fearful behav-
iors, increases in friendly behaviors, increases in playfulness, and normal
grooming behaviors. Some dogs might not adapt to human handling or the
environment and are therefore inappropriate for use in long-term studies.
The dealer should be questioned about the sources and histories of such
dogs to determine whether additional dogs purchased from that dealer will
be similarly distressed. Information on maladaptive canine behavior has
been published elsewhere (Scott, 1970).

Many procedures such as trimming of nails, removal of matted fur,
bathing, and teeth-cleaningcan be performed during the conditioning pe-
riod.

There is no definitive rule about the optimal period for conditioning.
The intended use of the dogs, the season, prevalence of canine diseases in
the area, and other factors influence the length of the conditioning period.
If the dogs are well selected, adequately socialized, immunized, and treated
for parasites before delivery, the conditioning period can be reduced. Ran-
dom-source dogs that have been held for 10 days or more by the dealer
usually require at least 21 days of conditioning at the institution before one
can be confident that they have adapted fully, Some prefer a minimal condi-
tioning period of 45 days. The importance of humane treatment and proper
care during conditioning must be emphasized.

CONTROL OF INFECTIOUS DISEASES

General Considerations

There are three important strategies for controlling canine infectious
diseases: examining dogs on arrival and refusing to accept dogs that exhibit

54 DOGS: LABORATORY ANIMAL MANAGEMENT

signs of disease, placing all newly acquired dogs in quarantine, and isolat-
ing dogs that become sick. Some infectious pathogens to which dogs are
susceptible could be introduced into an established colony by new arrivals,
especially by random-source dogs, which are commonly unvaccinated. The
most common of these pathogens are canine distemper virus (CDV); canine
parvovirus (CPV-2); canine herpesvirus (CHV); the respiratory agents ca-
nine parainfluenza (PI-2), Bordetella bronchiseptica, and Mycoplasma spp.;
canine adenovirus type 1 (CAV-1, infectious canine hepatitis) and type 2
(CAV-2, tracheobronchitis virus); and canine coronavirus (CCV). An addi-
tional problem that warrants careful consideration is the possibility that
unvaccinated random-source dogs can harbor rabies virus, which can have a
long incubation period (Acha and Szyfres, 1987). Dermatophytosis (ring-
worm, principally Microsporum canis and M. gypseum) and canine papillomatosis
(warts) can also present problems. Protection against these pathogens is
discussed briefly below. Detailed information on canine infectious diseases
is available in a number of general references (e.g., Appel, 1987; Barlough,
1988; Greene, 1990).

Quarantine

Quarantine (in this context, the isolation of newly acquired animals
until their health status has been evaluated) minimizes the risk of spreading
diseases from newly arrived dogs to those already in the colony. In most
facilities, the quarantine and conditioning periods overlap. During the quaran-
tine period, most attention is directed to the control of infectious diseases
and parasites. Procurement of dogs that are free of infectious diseases and
parasites (i.e., conditioned random-source dogs or dogs bred specifically for
research) reduces the time necessary for both quarantine and conditioning
and might result in more reliable research results. Nonconditioned random-
source dogs should be quarantined as a group, and no additional nonconditioned
dogs should be introduced into the group.

Quarantine facilities should be designed to provide physical barriers to
the spread of infectious diseases (e.g., unidirectional airflow). That is espe-
cially important when the research and quarantine facilities are parts of a
single building. It is preferable for a quarantine facility to have its own
animal-care technicians; however, if this is not possible, quarantined dogs
should be cared for last.

Newly arrived dogs should be housed singly to enable veterinarians and
technicians to determine which dogs are not eating well, exhibit signs of
disease, or are abnormal in other ways. Ideally, dogs are vaccinated by the
dealer. If not, they should be vaccinated as soon as possible after arrival
against CDV, CPV-2, and CAV-2 (such vaccination also protects against

VETERINARY CARE 55

CAV-1). Vaccination for PI-2 and B. bronchiseptica should be considered
in institutions where respiratory disease is common. If the dogs are to be
vaccinated against leptospirosis and rabies, that is usually done at the same
time. If a person is bitten or scratched, the injured area should be cleansed,
the person should be referred to appropriate medical personnel, and the dog
should be isolated for at least 10 days, as recommended by the National
Association of State Public Health Veterinarians (1993).

Research and Breeding Colonies

The major threat to an established colony is that newly introduced dogs
might harbor an infectious-disease agent or that personnel might carry such
an agent into the colony on their hands or clothing. A regular immunization
program, quarantine of nonconditioned random-source dogs, and rigorous
sanitation practices will help to protect against infectious agents inadvert-
ently introduced into an established colony. Annual vaccination with a
multivalent vaccine is generally recommended, although immunity to CDV
and CPV-2 generally persists for at least 3 years. In areas in which respira-
tory disease is common, frequent vaccination (every 3 months) might be
indicated. Frequent vaccination (every 6 months) with leptospira bacterins
is recommended in areas in which leptospirosis is endemic or is a proven
problem.

Breeding Stock

Some infectious diseases are of special concern in breeding colonies.
CHV can remain undetected in a breeding kennel for years. When suscep-
tible, pregnant (usually young) bitches are introduced into the colony, latent
CHV manifests itself by causing abortions or fetal or neonatal deaths. A
detailed discussion of CHV is available elsewhere (Carmichael and Greene
1990a).

Canine brucellosis can severely affect reproduction in a breeding ken-
nel. It is also a zoonosis. All dogs purchased for breeding stock should be
tested for Brucella canis antibodies on arrival and placed in quarantine for
at least 1 month, at which time a second brucellosis test should be run.
New dogs should not be introduced into a breeding colony unless both tests
are negative. An infected dog should not be used for breeding or for long-
term studies. Beagles have an unusually high prevalence of brucellosis,
although it is occasionally diagnosed in random-source dogs (Carmichael,
1979). For detailed discussions of canine brucellosis see Carmichael (1990)
and Carmichael and Greene (1990b).

56 DOGS: LABORATORY ANIMAL MANAGEMENT

Pups

CDV and CPV-2 infections are the principal viral diseases that threaten
pups during the first 4 months of life, and prevention of these diseases
should be the principal objective of an immunization program. Maternal
antibody to CDV interferes with the development of an immune response to
CDV vaccine; measles vaccine protects against disease but not infection in
pups in which maternal antibody is still present (pups about 6-10 weeks
old) (Baker, 1970). CDV vaccine should be given to dogs by 14 weeks of
age. No vaccines can prevent parvovirus infection in pups during one
critical period that during which they still have maternal antibodies that
inhibit the response to vaccination but do not protect against virulent CPV-
2 (Carmichael, 1983). Proper management practices are critical in prevent-
ing this infection. If a pup does contract the disease, it should be isolated
immediately, and rigorous disinfection procedures should be implemented.
Diseases caused by adenoviruses and CCV can occur in pups, but they are
less common.

It is generally recommended that modified live-virus vaccines be used
for immunization, if available. A killed-virus vaccine is used for rabies. A
multivalent vaccine that protects against distemper, hepatitis, leptospirosis,
and parvovirus and parainfluenza infections can be used. An intranasal
vaccine against Bordetella bronchiseptica, which causes kennel cough, is
generally recommended. Several vaccination regimens have been proposed
(Baker et al., 1961; Carmichael, 1983; Swango, 1983); one of them is given
in Table 5.1 as a guide, but others are acceptable. The vaccination schedule
should be adapted to address the perceived risk of infection.

Pups can be vaccinated with intranasal vaccine against B. bronchiseptica
at 3-4 weeks of age. Other than that, vaccinating pups less than 6 weeks
old is not recommended, because vaccine safety has not been studied in
very young pups. Isolation is more important than vaccination in prevent-
ing disease in such pups.

TABLE 5.1 A Vaccination Schedule for Pups

Age Vaccine

6 weeks CDV or CDV combined with measles and CPV-2

8-10 weeks CPV-2

12-14 weeks Multivalent vaccine

16 weeks CPV-2 (or multivalent vaccine) and rabies

VETERINARY CARE 57

Specific-Pathogen-Free Colonies

Dogs from known matings that have never been exposed to specific
infectious agents are called specific-pathogen-free (SPF) for those agents.
These dogs are used in infectious-disease and vaccine-development research
in which animals are required not only to be free from pathogenic agents,
but never to have been exposed, either naturally or through vaccination, to
pathogenic agents. It might also be preferable to use SPF dogs in some
transplantation studies, because in profound immunosuppression, native and
vaccinal viruses (e.g., CDV and CAV-1) might be activated and cause dis-
ease (Thomas and Ferrebee, 1961).

The objective in preventing the outbreak of disease in SPF colonies is
to isolate, rather than immunize, the dogs. Disease prevention depends on
the establishment of physical barriers to preclude the introduction of dis-
ease agents, rigorous management practices, and control of personnel move-
ment into and within the facility (Sheffy et al., 1961). Rodents and other
pests that can transmit disease mechanically must be excluded. Purpose-
bred SPF dogs are available commercially. If bred by the institution, initial
breeding stock should be procured from dogs free of latent infectious agents,
and all offspring taken by hysterectomy or cesarean section. Embryo-trans-
fer technology offers additional possibilities for SPF colonies. Population
immune status should be assessed periodically (at least once a year) by
monitoring for antibodies to the common infectious diseases. In the event
of an inadvertent infection that would compromise the use of the animals,
the colony should be depopulated and re-established.

CONTROL OF PARASITIC DISEASES

Parasites are common in dogs, particularly random-source dogs. They
can be found on the skin and hair and in the ears (ectoparasites) and in
many internal organs, including the digestive tract, heart, lung, and blood
vessels (endoparasites). Specific canine parasites are discussed briefly be-
low; details on life cycles of, treatment for, and prevention or control of
these parasites are found elsewhere (Georgi and Georgi, 1992).

Ectoparasites

Ectoparasites include ticks, mites, lice, and fleas. Most can be easily
eradicated with insecticides. Three ectoparasites commonly carried by ran-
dom-source dogs can pose problems if they are not eliminated during quar-
antine.

58 DOGS: LABORATORY ANIMAL MANAGEMENT

The most damaging is probably the Rhipicephalus sanguineus tick.
This tick can feed on dogs during all life-cycle stages, and once it enters a
facility, it can be expensive to remove.

Mange caused by Sarcoptes scabei is sometimes inadvertently in-
troduced into a facility on a dog that shows no overt signs of dermatosis.
This parasite can be a particular problem in dogs that are group-housed or
housed in cages or runs that allow the touching of body parts among ani-
mals (e.g., through wire-mesh walls). Sarcoptic mange is treated by dip-
ping the affected dogs and all dogs in contact with them in insecticide. It is
probably also worthwhile to steam-clean enclosures and floors.

Fleas are commonly brought into facilities by random-source dogs.
The flea life cycle can be disrupted by cleaning enclosures daily to remove
developing eggs and larvae. Another strategy is to house dogs in enclosures
raised more than 33 cm above the floor. Fleas cannot jump higher than 33
cm, so fleas that fall to or develop on the floor cannot reach the dog to feed.

Additional ectoparasitic infestations that might persist in kennel set-
tings include infestation with ear mites (Otodectes cynotis), "walking dan-
druff* (Cheyletiella yasguri), and lice (Linognathus setosus, Trichodectes
canis, and Heterodoxus spinigef). The canine nasal mite (Pnewnonyssoides
caninum) can also persist, but it is not known how often infestations with
this mite occur in random-source dogs.

To prevent the introduction of skin-dwelling ectoparasites, random-source
dogs should be bathed or dipped before they are moved to the housing
facility. Their ears should be examined and, if appropriate, treated for ear
mites. Mites should be considered as the cause of persistant skin lesions,
and appropriate action should be taken to make a correct diagnosis.

All dogs, including random-source and breeding-colony dogs, are prob-
ably host to the hair-follicle mite Demodex canis. Dogs probably become
infected as puppies while nursing. Typically, the infestation is nonpathogenic;
in rare instances, the mite causes severe mange. The development of demodectic
mange in large numbers of kennel dogs is rare but has occurred. Treatment
with topical applications or dips is possible as long as the lesions remain
focal, but generalized demodectic mange often indicates some underlying
problem (e.g., an inherited susceptibility to demodectic mange or a compro-
mised immune system), and its treatment is difficult or impossible.

Endoparasites

SPF dogs and purpose-bred dogs often host both protozoan and helmin-
thic endoparasites. The protozoa include Isospora spp., Giardia spp., tri-
chomonads, Cryptosporidium spp., Balantidium spp., and amebas. The hel-
minths include ascarids (e.g., Toxocara canis and Toxascaris leonina), Filaroides

VETERINARY CARE 59

spp., Strongyloides stercoralis, and occasionally hookworms and whipworms.
If dogs are housed in a manner that allows mosquitoes access to them, they
are also susceptible to infection with heartworm, Dirofilaria immitis.

Isospora spp. have direct life cycles (i.e., no intermediate host is re-
quired). Oocysts of these coccidia are commonly present in the feces of
young dogs raised in colonies, and more than one species can be present in
one dog. The oocysts of /. canis, L ohioensis, L neorivoltos, and /. burrowsi
are morphologically similar; however, those of/, canis are larger than those
of the other three. Clinical signs include increased temperature and diar-
rhea that is occasionally bloody. Infections usually subside after several
days to weeks. Oocyst shedding decreases to low numbers 4 weeks after it
begins. Chemoprophylaxis and basic sanitation are necessary to control the
infection if it causes problems.

Cryptosporidium is occasionally present in dogs in closed colonies,
although it typically does not cause disease. In immunocompetent dogs, the
small oocysts of Cryptosporidium are shed in low numbers, if at all, for a
limited period; however, in immunosuppressed or immunocompromised dogs,
Cryptosporidium can cause fatal disease. There is no proven method of
Chemoprophylaxis or treatment, but routine sanitation procedures, accompa-
nied by regular steam cleaning of areas that might be contaminated, will
assist in reducing exposure to oocysts.

Giardia canis is commonly present in both purpose-bred and SPF dogs.
The prevalence is high in pups and decreases with age. The organism is
spread between dogs by the fecal-oral transmission of resistant cysts. Typi-
cally, pups are infected with Giardia and one or more species of Isospora;
however, the infection usually causes little or no disease. As dogs mature,
the number of organisms decreases. As with Isospora, Chemoprophylaxis
and basic sanitation are the most effective means of controlling Giardia.

Trichomonas canistomae is a commensal organism present in the mouths
of many dogs. It has no cyst stage and is transmitted between dogs by
direct oral contact. There is usually no need for treatment. Species of
Trichomonas and Pentatrichomonas are present in the large intestines of
many laboratory-reared dogs. None of these species has a cyst stage; trans-
mission is by the fecal-oral route. These organisms are sometimes observed
in diarrheic feces in very large numbers, but they are usually not the cause
of the diarrhea. Treatment is available but usually not necessary.

Balantidium coli, a large ciliated parasite that is rarely found in dogs,
and Entamoeba coli and E. histolytica, smaller ameboid parasites, are trans-
mitted by cysts passed in the feces. These parasites are present in the large
bowel. Their life cycles are similar to that of Giardia, and once they are
established in a colony, they are easily perpetuated.

The ascaridoid nematode (roundworm), Toxocara canis, is a common
parasite of the small intestines of dogs, even in closed breeding colonies.

60 DOGS: LABORATORY ANIMAL MANAGEMENT

The parasite is transmitted from bitches to pups in utero, and pups begin to
shed eggs in their feces a few weeks after birth. Once the eggs enter the
environment, they require about 2 weeks to become infectious; they are
very resistant to environmental extremes of heat, cold, and humidity. Pups
should be treated soon after birth and several times during early life to
prevent the development of adult roundworms from the stages obtained
prenatally. Control measures should include steam cleaning of floors and
disinfection of floors with a 1:4 (20 percent) solution of chlorine bleach.
Adult dogs can have larvae in their tissues whether or not they are shedding
eggs in their feces. It is possible to determine whether a dog has ever been
infected by measuring antibody concentrations, and dogs that are Toxocara
canis-naive are available commercially.

The other canine ascaridoid, Toxascaris leonina, has a direct life cycle
and does not infect pups transplacentally. The eggs of this parasite develop
more rapidly than those of Toxocara canis but are just as resistant to ex-
tremes of heat, cold, and humidity. Toxascaris leonina is commonly present
in the small intestines of older purpose-bred and SPF dogs, but it is not
known how the cycle is maintained in these colonies. Control and treat-
ment are the same as those used for Toxocara canis.

Filaroides hirthi is present in the lung parenchyma of many purpose-
bred and SPF dogs. The lung lesions caused by the parasite can confuse
histopathologic evaluations in toxicologic experiments. The life cycle is
direct, and infective larvae are transmitted between dogs by oral or fecal-
oral contact. Immunosuppressed dogs can become seriously ill as a result
of auto-reinfection that leads to heavy parasite burdens. Infections can be
treated, but control is difficult because fecal assays are insensitive. There-
fore, all dogs in a contaminated room must be treated, not just those with
positive fecal tests. Proper sanitation is helpful, but the larvae do not
persist for long periods in the environment.

Strongyloides stercoralis lives as a parthenogenetic female in the mu-
cosa of the canine small intestine. Larvae develop to the infective stage 4-5
days after they are passed in feces. Transmission is by penetration of the
skin by infective-stage larvae and by passage of tissue-dwelling larvae in
the milk of lactating bitches. Immunosuppressed or immunocompromised
dogs can develop severe disease as a result of auto-reinfection. S. stercoralis
is also transmissible to humans. Although treatment is available, elimina-
tion of the parasite from a breeding colony is difficult because it is not
certain that transmammary transmission can be interrupted by chemothera-
peutic measures. Routine removal of feces and cleaning of cage or pen
floors reduce transmission.

Adult hookworms live in the small intestine, where they cause blood
loss and anemia. The hookworms Ancylostoma caninum and A. braziliense,
like S. stercoralis, are transmitted through the milk or by larval penetration

VETERINARY CARE 61

of the skin. However, infective-stage larvae are more likely to develop in
soil than on a moist cage bottom fouled with feces, and transmission is
more likely when dogs are housed outside on such surfaces as gravel or
sand. Unlike dogs infected with S. stercoralis, dogs infected with hook-
worms often show signs of overt disease, characterized by bloody diarrhea.
In addition, hookworm eggs are much easier to detect in feces than are 5.
stercoralis larvae. Those differences and the dissimilarity of conditions
required for larval development make it much less likely that hookworms
will persist undetected in a colony. The hookworm Uncinaria stenocephala,
which is present in more temperate climates, is transmitted mainly by larval
ingestion; skin penetration and transmission in milk are uncommon. Thus,
U. stenocephala is less likely to be perpetuated in a closed colony.

Whipworms, Trichuris vulpis, live in the cecums and colons of dogs
and cause large bowel disease that can produce bloody stools. The life
cycle of this parasite is direct. Eggs are passed in feces and take several
weeks to become infectious. They are highly resistant to environmental
extremes, so contamination is very peristent if eggs get into the soil of
earthen-floored runs. Dogs become infected by ingesting the infective eggs
on soil-contaminated items. In the dog, the worms take about 3 months to
develop to the adult stage, and reinfection is common. Treatment is avail-
able but often has to be repeated.

The filarioid nematode Dirofilaria immitis causes heartworm disease.
It is transmitted between dogs by the bite of a mosquito. The prepatent
period (the time between the inoculation of maturing forms by the mosquito
and the first appearance of microfilariae in the host's blood) is slightly
more than 6 months. The infection is often manifested as cardiopulmonary
disease accompanied by respiratory distress and right-sided heart enlarge-
ment. In dogs with patent disease, infections can be diagnosed by demon-
strating microfilariae in the blood; however, some infected dogs do not
have circulating microfilariae (Glickman et al., 1984.). When it is impor-
tant to ascertain that dogs are heartworm-free, serum or plasma can be
examined with antigen-detection tests. Treatment for heartworm infection
is generally precluded by its high cost, the stress it causes the dog, the
length of time necessary for recovery, and the possibility of residual pathologic
changes in the cardiovascular system.

Where D. immitis is enzootic, dogs given access to outside runs should
be protected by chemical prophylaxis. If dogs cannot be placed on chemi-
cal prophylaxis, because of a study design or for other reasons, they can be
protected by enclosing the outside kennels with screening.

In addition to infection with the same parasites found in purpose-bred
and SPF dogs, random-source dogs are likely to be infected with parasites
that are relatively rare or that require intermediate hosts as part of their life
cycles. If the intermediate hosts are uncommon (e.g., snails, then crayfish

62 DOGS: LABORATORY ANIMAL MANAGEMENT

for the lung fluke Paragonirnus kellicotti), there is little chance that the
infection will be maintained in a kennel. However, if the intermediate host
is commonly present around dogs (e.g., fleas for the tapeworm Dipylidium
caninum), the parasite will probably persist in the facility as long as the
intermediate host is present. Additional parasites that can be found in
random-source dogs include the tapeworm Taenia spp. (intermediate hosts,
mammals), the intestinal fluke Alaria canis (snails, then frogs), the esoph-
ageal nematode Spirocerca lupi (beetles), and the stomach nematode Physaloptera
spp. (beetles).

Two parasites that are found rarely in random-source dogs, Echinococ-
cus spp. and Trypanosoma cruzi, are important because they cause zoonoses.
Larval stages of the canine tapeworms Echinococcus granulosus and E.
multilocularis can be transmitted to humans in contaminated feces and cause
unilocular and multilocular hydatid disease, respectively. Eggs of Echino-
coccus spp. are infectious when passed in feces and cannot be distinguished
morphologically from eggs of taeniid tapeworms. E. granulosus is present
in focal areas of the United States; E. multilocularis is present in the far
northern continental United States, Alaska, and Canada. Trypanosoma cruzi,
which is present in the southern United States, is a hemoflagellated proto-
zoan that can infect the blood and tissues of opossums, armadillos, dogs,
humans, and other mammals. Humans are infected by accidental self-in-
oculation with blood products from an infected animal. People handling
dogs from areas where Echinococcus spp. and T. cruzi are enzootic should
be made aware that such infections, although rare, are possible and can be
associated with life-threatening conditions in humans.

Three other uncommon canine pathogens, all requiring arthropod vec-
tors, have occasionally been diagnosed in dog facilities: Leishmania spp.,
Babesia spp., and Ehrlichia canis. The clinical signs caused by these pathogens
are often poorly deliniated, so they can be harder to diagnose than common
helminth infections.

Cutaneous and visceral leishmaniasis, caused by infections with various
species of Leishmania, have been reported in both kennels and research
colonies. The organism is typically transmitted between dogs by the bite of
a phlebotomine sandfly, although the mode of transmission in the reported
cases is not certain. Diagnosis is typically made by identifying the organ-
isms histopathologically or serologically. Treatment is difficult but pos-
sible.

Babesiosis, caused by Babesia canis or Babesia gibsoni, can be intro-
duced into colonies or kennels through an infected dog, an infected tick, or
a blood transfusion. Once it is in an establishment, horizontal transmission
typically occurs through exposure to infected blood that is not handled
properly or through ticks, particularly Rhipicephalus sanguineus. Dogs
with babesiosis display regenerative anemia, i.e., the bone marrow remains

VETERINARY CARE 63

functional, and increased numbers of immature erythrocytes appear in the
blood. The disease can be diagnosed by demonstrating the organisms in
erythrocytes on stained blood films. Treatment is difficult, and drugs rou-
tinely used in parts of the world where babesiosis is common are not easily
obtained in the United States.

Transmission of ehrlichiosis, a rickettsial infection caused by Ehrlichia
canis, is similar to transmission of babesiosis. Signs of ehrlichiosis in dogs
include fever, anorexia, epistaxis (nosebleeds), and reduced kidney func-
tion. Diagnosis is made serologically or by demonstrating the presence of
the organism in blood smears. Treatment can alter the course of the disease
but does not prevent an affected dog from becoming a carrier of the infec-
tion.

Good sanitation is probably the major means for controlling endopara-
sites in a dog facility. In facilities that house purpose-bred or SPF dogs,
feces from healthy animals of different ages should be examined periodi-
cally for subclinical helminth or protozoan infections. Fecal and blood
examinations can be used to screen random-source dogs for parasites on
arrival at the facility. To prevent the introduction of helminth parasites into
a facility, random-source dogs might be treated for some infections with an
anthelminthic. A practical choice would be a broad-spectrum anthelminthic
that is active against both nematodes and tapeworms.

RECOGNITION AND ALLEVIATION OF PAIN AND DISTRESS

Recognition of Distress Induced by Pain

Distress can be defined as "an aversive state in which an animal is
unable to adapt completely to stressors and the resulting stress . . ." (NRC,
1992, p. 4). Scientists have legal, ethical, and humane obligations to mini-
mize distress in experimental animals. Moreover, there is a pragmatic rea-
son to minimize distress. Unless a stressor (such as pain) is the subject of
the experiment, distressed animals might provide erroneous data (Amyx,
1987). Pain is an important cause of distress and is usually produced by
disease, injury, or surgery.

Table 5.2 lists some of the signs of pain in dogs. Dogs usually respond
to acute pain by vocalizing and by protecting or guarding the area of per-
ceived pain. Signs include withdrawing, attempting to bite if touched, and
adopting unusual postures (e.g., the laterally flexed position commonly adopted
after lateral thoracotomy). Low-grade pain can produce restlessness. Se-
vere pain, especially if chronic, usually makes dogs appear depressed and
lethargic. The decrease in activity can be accompanied by one or more of
the following: shivering, inappetence, panting, howling, or whining.

The U.S. Government Principles for Utilization and Care of Vertebrate

64 DOGS: LABORATORY ANIMAL MANAGEMENT

TABLE 5.2 Signs of Pain in Dogs*

Sign Comment

Guarding Attempting to protect or move painful part away (e.g., hunched position

after celiotomy or laterally flexed position after lateral thoracotomy),
attempting to bite

Vocalization Whining or whimpering when touched or forced to use affected part

Mutilation Licking, biting, scratching, shaking, or rubbing affected part

Restlessness Pacing, lying down and getting up, or shifting weight

Recumbency For unusual length of time

Depression Inappetence, reluctance to move, or difficulty in rising

Pallor Pale mucous membranes, probably a result of vasoconstriction caused by

an increase in sympathetic tone

Adapted from Soma, 1987; printed with permission of the author, the American Association
for Laboratory Animal Science, and the Scientists Center for Animal Welfare.

Animals Used in Testing, Research, and Training (published in NRC, 1985)
states that "unless the contrary is established, investigators should consider
that procedures that cause pain or distress in human beings may cause pain
or distress in other animals.*' This statement makes it clear that most surgi-
cal interventions must be accompanied by adequate anesthesia and suitable
postoperative analgesia. Table 5.3 lists the degree and duration of pain that
can be expected after surgery on various parts of a dog's body. Although
pain thresholds are similar between individuals and even between species,
pain tolerance varies widely. Therefore, each dog should be observed and
treated as an individual in determining the need to administer analgesics.

Alleviation of Pain

Anesthetics

General anesthesia is the most important way of alleviating pain associ-
ated with surgery, and several textbooks contain detailed descriptions of
acceptable techniques for inducing general anesthesia in dogs (Booth, 1988a;
Hall and Clarke, 1991; Lumb and Jones, 1984; Muir and Hubbell, 1989;
Short, 1987). Inhaltant agents (e.g., isoflurane, methoxyflurane, and halothane)
are often best for this purpose because they allow close regulation of the
duration and depth of anesthesia and rapid and controlled reversibility. How-
ever, special equipment is required for administering them. Nitrous oxide
is not a general anesthetic in dogs and should be used only as an adjunct to
other, more potent anesthetics.

General anesthesia can also be provided with injectable drugs, such as
barbiturates (e.g., thiamylal, thiopental, and pentobarbital), propofol, or Telazol

VETERINARY CARE

TABLE 5.3 Signs, Degree, and Length of Surgically Produced Pain*

Surgical Site Signs of Pain

Degree of Pain

Length of Pain

Head, eye, ear, Attempts to rub or scratch; Moderate to high Intermittent to

mouth self-mutilation; shaking; continual

reluctance to eat, drink,

or swallow; reluctance

to move
Rectal area Rubbing, licking, biting, Moderate to high Intermittent to

abnormal bowel movement continual

or excretory behavior
Bones Reluctance to move, lameness,

abnormal posture, guarding,

licking, self-mutilation

Moderate to high: Intermittent

upper part of axial

skeleton (humerus,

femur) especially

painful
Not obvious to Short

moderate
Sternal approach, Continual

high; lateral

approach, slight

to moderate
Moderate to severe Continual

Abdomen Abnormal posture (hunched),

anorexia, guarding
Thorax Reluctance to move, respiratory

changes (rapid, shallow),

depression

Spine, cervical Abnormal posture of head

and neck, reluctance to

move, abnormal gait-

"walking on eggs"

Spine, thoracic Few signs, often moving Slight Short

or lumbar immediately

a Based on observations of dogs. Reprinted from NRC, 1992.

(a mixture of tiletamine and zolazepam). Each injectable drug has proper-
ties that determine its duration of action and the route by which it is best
administered. Ketamine is used as an anesthetic but its effectiveness as an
analgesic for visceral pain is disputed (Booth, 1988b; Hughes and Lang,
1983). It should be used in combination with another analgesic agent when
visceral pain is expected. It can also induce seizure-like activity in dogs
unless it is used in conjunction with another drug, such as diazepam, aceproma-
zine, or xylazine. Chloralose and urethane are injectable anesthetics that
have been used in some experiments; however, chloralose alone is a poor
anesthetic that produces little analgesia unless it is combined with an opiate
such as morphine (Rubal and Buchanan, 1986), or a short-acting anesthetic
(Flecknell, 1987). Urethane is mutagenic and carcinogenic (Auerbach, 1967;
Mirvish, 1968); it should be used with caution and only for nonsurvival
surgery.

Neuromuscular blocking agents (e.g., succinylcholine, atracurium, curare,

66 DOGS: LABORATORY ANIMAL MANAGEMENT

gallamine, pancuronium, and vecuronium) have no anesthetic or analgesic
properties. They must not be used alone for surgical restraint, although
they may be used in conjunction with anesthetic doses of general anesthetic
drugs (NRC, 1985).

Local anesthetics (e.g., lidocaine, mepivacaine, and bupivacaine) act to
disrupt nerve conduction temporarily. When applied around a nerve, they
produce analgesia in the region served by that nerve. However, these drugs
have no depressant effect on the brain; dogs undergoing procedures under
local anesthesia usually must be restrained physically or chemically (e.g.,
with tranquilizers or sedatives). Specific techniques for regional anesthesia
are described in several texts (Hall and Clarke, 1991; Lumb and Jones,
1984; Muir and Hubbell, 1989; Skarda, 1987; Soma, 1971). Local anesthet-
ics alone are ordinarily used for only the most minor of surgical interven-
tions; but they can be given either intrathecally or epidurally (usually via
the lumbosacral space) to provide segmental anesthesia of caudal body parts
sufficient for major surgery (e.g., celiotomy) (Skarda, 1987).

Analgesics

Opioid analgesics are compounds that act at specific opioid receptor
sites in the central nervous system to produce analgesia. Table 5.4 lists
some of these compounds. They are not general anesthetics, but can be
used for surgery when combined with other appropriate drugs (NRC, 1992).
Opioid analgesics (e.g., oxymorphone) can be injected epidurally to control
postsurgical pain for extended periods with minimal systemic effects (Popilskis
et al., 1991).

Opioid agonists have been combined with tranquilizers to produce so-
called neuroleptanalgesic combinations (e.g., a mixture of fentanyl and droperi-
dol known by the trade name Innovar-Vet and produced by Pitman Moore,
Mundelein, 111.). Such combinations are capable of producing a state that

TABLE 5.4 Opioid Analgesics Used in Dogs*

Drug Dose (mg/kg) Route**

Buprenorphine

0.01-0.2

IV, IM

Butorphanol

0.2-0.5

IV, IM

Fentanyl

0.04

IV, IM

Meperidine

2.0-6.0

Morphine

0.5-1.0

Oxymorphone

0.2-0.4

IV, IM

*Data from Harvey and Walberg, 1987.

b lV = intravenous; IM = intramuscular; SC = subcutaneous

VETERINARY CARE 67

sufficiently resembles general anesthesia to permit some surgical proce-
dures (Muir and Hubbell, 1989; Soma and Shields, 1964). Xylazine, which
is classified as a sedative, has analgesic properties because of its action on
central alpha-2 receptor sites.

The nonsteroidal anti-inflammatory analgesics include acetaminophen,
aspirin, flunixin, and ibuprofen. These drugs inhibit prostaglandin synthe-
sis. They are ordinarily used to relieve the acute or chronic pain associated
with inflammation and have little place in the management of severe or
acute pain that is not associated with inflammation (NRC, 1992).

Recognition of Distress Not Induced by Pain

Signs of distress caused by stressors other than pain include changes in
behavior (e.g., unexpected aggression), maladaptive behaviors (e.g., stereotypies),
and physical changes (e.g., weight loss). Experienced and attentive animal
caretakers are of the utmost importance in early recognition of signs of
distress. Changes in biochemical measurements (e.g., plasma cortisol con-
centration) can also help in recognition of distress.

Alleviation of Distress Not Induced by Pain

Distress caused by stressors other than pain is often related to hus-
bandry practices. Understanding and meeting dogs' social and physical needs
will minimize or prevent such distress (NRC, 1992).

Phenothiazine tranquilizers, such as acepromazine (0.03-0.05 mg/kg in-
travenously or intramuscularly, 1.0-3.0 mg/kg by mouth), are useful as
preanesthetic drugs because they make unruly animals more tractable, re-
duce the doses of anesthetic drugs necessary to maintain anesthesia, and
make recovery from anesthesia smoother. However, they can have unpre-
dictable effects and cause some animals to become excited rather than tran-
quil (Voith, 1984). The phenothiazines have minimal antianxiety effects,
and they are not the drugs of choice for decreasing fearful reactions (Marder,
1991).

Alpha-2 agonists, such as xylazine (0.3-1.0 mg/kg intravenously, 0.5-
2.0 mg/kg intramuscularly), have many of the advantages of the phenothia-
zines and are also good analgesics (Gleed, 1987). However, they can cause
serious cardiovascular depression, hyperglycemia, and depressed thermoregula-
tion, which can be reversed with yohimbine if necessary (Denhart, 1992),

Benzodiazepines, such as diazepam (0.1-0,5 mg/kg intravenously, 0.3-
0.5 mg/kg intramuscularly) are often used as adjuncts to injectable anes-
thetic drugs, such as the barbiturates and ketamine, because they reduce the
dose necessary to produce anesthesia and provide muscle relaxation (Gleed,
1987). Diazepam (Valium) is also used alone to treat seizures. Like the

68 DOGS: LABORATORY ANIMAL MANAGEMENT

phenothiazines, the benzodiazepines have an excitatory effect on some ani-
mals. Because they are the drugs of choice for the treatment of fearful
behaviors (Marder, 1991), especially fear of people (Hart, 1985), they can
be useful in reducing distress in unsocialized dogs. However, the benzodi-
azepines must be used with care in dogs that display fear-motivated aggres-
sion. Decreasing the fear might make such dogs more likely to attack
(Marder, 1991).

SURGERY AND POSTSURGICAL CARE

Surgery in dogs should be performed in accordance with the tenets in
the Guide (NRC, 1985). The requirements for minor and nonsurvival surgi-
cal procedures are less stringent than those for major survival surgical pro-
cedures.

Personnel performing surgical procedures must be adequately trained.
Facilities for performing surgical procedures should be available as outlined
in the Guide (NRC, 1985). The successful practice of survival surgery
requires strict adherence to aseptic surgical technique, as well as provision
of adequate postoperative care and analgesia for the experimental subject.
Aseptic techniques also have some value in major nonsurvival surgical pro-
cedures (Slattum et al., 1991). Generally, only healthy conditioned or pur-
pose-bred dogs should be used for survival surgery. Familiarizing the dog
with the laboratory environment can assist investigators in identifying in-
tractable subjects and can be beneficial in decreasing postoperative stress.

Presurgical Preparation

Dogs should be surgically prepared by careful shaving to remove all
hair from the surgical field. Shaving reduces contamination of the wound
and avoids delays in healing that can occur if hair becomes matted in the
incision. If a thermal cautery is to be used, an area should also be shaved
for placement of a ground lead. Adherent grounding pads are available.
The surgical field should be thoroughly cleaned with Betadine (povidone-
iodine) or another appropriate surgical scrubbing material. Betadine sterile
solution or other appropriate preparation should be applied to the entire
field and allowed to dry. Underpadding used to absorb such solutions can
be flammable and should be removed before surgery.

All surgical instruments and chronic instrumentation must be sterilized
with steam (autoclaving) or gas (ethylene oxide with proper poststerilization
aeration time). Cold chemical sterilization is appropriate for minor surgical
procedures, but exposure time must be adequate, and the instruments must
be thoroughly rinsed in sterile saline before they come into contact with
body tissues. All items should be packaged for sterilization in such a way

VETERINARY CARE 69

that they can be opened and positioned for use without compromising steril-
ity. Investigators should follow standard surgical practices: donning surgi-
cal caps and masks, scrubbing, and donning surgical gowns and gloves.
Sterile drapes should be positioned on the dog to define the surgical field.
During the course of surgery, procedures for preserving sterility should be
strictly followed.

Generally, dogs should be treated with the appropriate preanesthetic
medications (e.g., tranquilizers and atropine) to provide a degree of seda-
tion and facilitate handling. General anesthesia is reviewed in the section
"Alleviation of Pain" (see pages 64-67); the type used depends on the type
and duration of the surgical procedure. The adequacy of anesthesia can be
assessed by the absence of the eyelid reflex and by the lack of withdrawal
in response to painful stimuli (e.g., toe pinch). Insertion of a cuffed endot-
racheal tube will ensure patency of the respiratory tract.

The physiologic status of dogs under general anesthesia should be as-
sessed by monitoring such parameters as pulse rate, systemic blood pres-
sure, and respiratory rate. Electrocardiography can be used to monitor the
status of the heart. A heating pad is useful for maintaining body tempera-
ture. If inhalant anesthetics are used, the anesthetized dog should be venti-
lated (tidal volume, 15-20 ml/kg; respiratory rate, 13-20 breaths/minute),
and carbon dioxide should be monitored. Respiratory rate, tidal volume,
and inspiratory-expiratory ratio can be adjusted to achieve acceptable end-
tidal carbon dioxide (38-40 torr) and blood oxygen saturation greater than
90 percent.

An intravenous catheter should be placed in the cephalic vein to pro-
vide a continuous intravenous drip (e.g., of lactated Ringer's solution) for
volume replacement and to ensure rapid access to the circulatory system.
Depending on the situation, antibiotics can be administered through the
catheter or intramuscularly. There is evidence that giving antibiotics during
the 2 hours before surgery is more beneficial than giving them either during
or after surgery (Classen, 1992).

Postsurgical Care

Appropriate analgesics should be administered for postoperative pain,
as needed (see pp. 66-67 and NRC, 1992). Surgical wounds and sites of
instrument entry into the body should be cleaned and treated daily (e.g.,
with 0.3 percent hydrogen peroxide or dilute Betadine solution). Topical
antibiotics (e.g., bacitracin ointment) can be applied. Surgical dressings
should be changed every day.

Basic biologic functions including urination, defecation, and appetite
are good indicators of a dog's overall physical well-being. These are easy
to observe and should be monitored regularly and often. Followup clinical

70 DOGS: LABORATORY ANIMAL MANAGEMENT

examinations and laboratory tests can be used to identify specific problems.
Appropriate supportive care should be provided as needed.

A commonly used experimental protocol involving major survival sur-
gery in the dog is the implantation of instruments that allow physiologic
measurements over a long period while the dog is conscious. The dog is
particularly suitable for this type of protocol because of its size, its equable
temperament, and the close parallelism of its physiologic functions with
those of humans. Strict adherence to the recommendations above will mini-
mize confounding effects.

EUTHANASIA

Euthanasia is a method of killing an animal rapidly and painlessly (NRC,
1985). It should be carried out by trained personnel following current
guidelines established by the American Veterinary Medical Association (AVMA)
Panel on Euthanasia (AVMA, 1993 et seq.; NRC, 1985) The method used
must produce rapid unconsciousness and subsequent death without evidence
of pain or distress, or the animal must be anesthetized before being killed (9
CFR 1.1). The method used should also be safe for attending personnel, be
easy to perform, and cause death without producing changes in tissues that
might interfere with necropsy evaluation. Methods of euthanasia recom-
mended by the AVMA Panel on Euthanasia (AVMA, 1993) are discussed
below.

Injection of Lethal Substances

Injection of a lethal substance is probably the most suitable method for
euthanatizing laboratory dogs. It usually involves the intravenous injection
of a large dose of a barbiturate anesthetic, such as pentobarbital (more than
100 mg/kg). The advantage of this method is that the animal is anesthetized
within seconds and does not undergo the pain or distress that might be
associated with later respiratory and cardiac arrest. In fact, cardiac arrest
can be delayed for many minutes after the onset of anesthesia; therefore,
cardiotoxins (e.g., large doses of dibucaine) are sometimes used to hasten
death (Wallach et al., 1981). Unruly or aggressive dogs should be sedated
or tranquilized to facilitate the restraint necessary for smooth intravenous
injection. Intravenous injection is the preferred route of administration
because venipuncture is easily performed on most dogs by trained, experi-
enced personnel. Injection outside the circulatory system is less reliable, is
potentially painful, and almost invariably produces a slow onset of action.

Injectable drugs such as magnesium sulfate, potassium chloride, and
neuromuscular blocking agents (e.g., atracurium, curare, gallamine, pancuron-
ium, succinylcholine, and vecuronium) may be used (Bowen et al., 1970;

VETERINARY CARE 71

Hicks and Bailey, 1978); however, the dogs must be in a deep plane of
anesthesia before drug administration (AVMA, 1993). Strychnine and nico-
tine are not suitable for euthanasia, because their stimulant properties might
cause distress even in anesthetized animals.

Inhalation Methods

Overdose of a potent inhalant anesthetic (e.g., halothane and isoflurane)
is satisfactory for performing euthanasia on dogs and is particularly appro-
priate for young dogs, in which venipuncture can be difficult. Anesthetic
vapors tend to be irritating; therefore, the animals should be tranquilized
first. If anesthetic vapors are used, a system for scavenging excess vapor is
necessary to comply with federal guidelines on anesthetic-vapor pollution
(CDC, 1977). Ether, unlike most contemporary inhalant anesthetics, is flam-
mable and explosive; therefore, its use is not recommended.

Carbon monoxide and carbon dioxide both cause death by hypoxia.
Carbon monoxide is impractical in most instances because of the risk to
operators and the complexity of the equipment to administer it. Carbon
dioxide has anesthetic properties and can be used for euthanasia (Carding,
1968; Leake and Waters, 1929); however, unless the chamber is well de-
signed and used properly, dogs can become distressed before becoming
unconscious. Hypoxia is not satisfactory for euthanatizing pups because
young animals tolerate hypoxia better than older dogs and can survive for
more than 30 minutes (Glass et al., 1944).

Physical Methods

Exsanguination is acceptable for euthanasia; however, the dog must be
anesthetized because the decreasing blood flow causes anxiety and auto-
nomic stimulation (Gregory and Wotton, 1984). Electrocution is considered
a humane method of euthanasia, provided that sufficient current passes through
the animal's brain to produce unconsciousness before or coincidentally with
the onset of cardiac arrest. However, this method of euthanasia is not
practical in most laboratories because of the danger to personnel (AVMA,
1993; Roberts, 1954; Warrington, 1974). Decapitation of pups is not rec-
ommended by the AVMA Panel on Euthanasia (1993),

Human Considerations

Euthanasia of dogs or any other animals can be stressful for the person-
nel performing the procedure. The degree of distress experienced by people
observing or performing euthanasia depends on their backgrounds, personal
philosophies, and ethical views on the use of animals in research (Arluke,

72 DOGS: LABORATORY ANIMAL MANAGEMENT

1988). People often transfer to the death of animals their unpleasant reac-
tions to human death, and their responses to euthanasia can be magnified
when strong bonds exist between them and the dogs being killed (e.g.,
strong bonds often develop between animal-care personnel and seriously ill
canine models that require a great deal of care and rely totally on their
human guardians). The stress experienced can be manifested as absentee-
ism, belligerence, careless and callous handling of animals, and high turn-
over rate. To be responsive to those concerns, institutional officials and
supervisors should be aware of and sensitive to the issues and should pro-
vide opportunities for individual and group discussion and support and for
educational programs that furnish factual information about euthanasia and
teach stress-management and coping skills (NRC, 1991).

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Special Considerations

PROTOCOL REVIEW

One of the many important responsibilities of an institutional animal
care and use committee (IACUC) is to review the protocols of research
projects in which dogs will be used (9 CFR 2.31; PHS, 1986). The proto-
col-review mechanism is designed to ensure that investigators consider the
care and use of their animals and that protocols comply with federal, state,
and institutional regulations and policies. In addition, the review mecha-
nism enables an IACUC to become an important institutional resource, as-
sisting investigators in all matters involving the use of animals. Although
the discussion below is directed to the use of dogs in research, the review
requirements apply to all vertebrate species.

Each research protocol must completely (but concisely) delineate the
proposed study, including a description of each of the following:

the purpose of the study;

the rationale for selecting dogs as the research subjects;

the breed, age, and sex of the dogs to be used;

the numbers of dogs in various groups of the protocol and the total
number to be used;

experimental methods and manipulations;

experimental manipulations that will be performed repeatedly on an
individual dog;

SPECIAL CONSIDERATIONS 77

preprocedural and postprocedural care and medications;

procedures that will be used to minimize discomfort, pain, and dis-
tress, including, where appropriate, the use of anesthetics, analgesics, tran-
quilizers, and comfortable restraining devices;

the euthanasia method, including the reasons why it was selected and
whether it is consistent with the recommendations of the American Veteri-
nary Medical Association Panel on Euthanasia (AVMA, 1993, et seq.);

the process undertaken to ensure that there are no appropriate in
vitro alternatives, that there are no alternative methods that would decrease
the number of animals to be used, and that the protocol does not unneces-
sarily duplicate previous work; and

the qualifications of the investigators who will perform the proce-
dures outlined.

One approach used by lACUCs is to have a scientifically knowledge-
able member thoroughly review the protocol. The reviewer contacts the
investigator directly to clarify issues in question. Later, at an IACUC meet-
ing, the reviewer presents and discusses the protocol and relates discussions
with the investigator. Changes or clarifications in the protocol that have
resulted from the reviewer's discussions with the investigator are submitted
to the IACUC in writing. After presentation of the protocol, the reviewer
recommends a course of action, which is then voted on by the IACUC.
Another kind of protocol review (which is especially effective in small
institutions with few grants) is initial review by the entire IACUC; results
are generally available to the investigator within a short period.

Several outcomes of protocol review are possible: approval, approval
contingent on receipt of additional information (to respond to minor prob-
lems with the protocol), deferral and rereview after receipt of additional
information (to respond to major problems with the protocol), and with-
holding of approval. If approval of a protocol is withheld, an investigator
should be accorded due process and be given the opportunity to rebut the
lACUC's critique in writing, to appear in person at an IACUC meeting to
present his or her viewpoint, or both. It is also important that provision be
made for expedited review, in which a decision is reached within 24-48
hours. Expedited reviews should be used only for emergency or extenuat-
ing circumstances. When a protocol is submitted for expedited review,
each member of the IACUC must have an opportunity to review it and may
call for a full committee review before approval is given and before animal
work begins (McCarthy and Miller, 1990).

The question of protocol review for scientific merit has been handled in
a variety of ways by lACUCs, Many protocols are subjected to extensive,
external scientific review as part of the funding process; in such instances,
the IACUC can be relatively assured of appropriate scientific review. In

78 DOGS: LABORATORY ANIMAL MANAGEMENT

the case of studies that will not undergo outside review for scientific merit,
many lACUCs require signoff by the investigators, department chairmen, or
internal review committees; this makes the signer responsible for providing
assurance that the proposed studies have been designed and will be per-
formed "with due consideration of their relevance to human or animal health,
the advancement of knowledge, or the good of society" (NRC, 1985, p. 82;
PHS, 1986, p. 27). Occasionally, IACUC members and investigators differ
as to the relevance of proposed studies to human and animal health and the
advancement of knowledge. Each institution should develop guidelines for
dealing with this potential conflict.

RESTRAINT

Some form of restraint is generally necessary to control a dog during a
procedure (see guidelines in NRC, 1985, p. 9). The method used should
provide the least restraint required to allow the specific procedure to be
performed properly, should protect both the dogs and personnel from harm,
and should avoid causing distress, physical harm, or unnecessary discom-
fort. In handling and restraining dogs, it is helpful to understand species-
typical behavior patterns and communication systems.

A small or medium-size dog can be picked up by placing one hand
under the chest and abdomen while restraining the head with a leash. Lift-
ing a large dog might require two people. It is important to remember that
males are sensitive to touch near their genitalia. Minor procedures, such as
taking a rectal temperature or administering a subcutaneous injection, can
usually be accomplished by one person using minimal restraint. During
venipuncture, sufficient restraint should be used to avoid repeated needle
insertions and to prevent the development of painful hematomas. Kesel and
Neil (1990) detail methods for handling and restraining animals.

If dogs are to be restrained frequently or for long periods or if the
restraint method used is especially rigorous, it might be necessary to train
them to tolerate the restraint. Training sessions should use positive-rein-
forcement techniques; negative-reinforcement techniques are not desirable.
Physical abuse (9 CFR 2.38f2i) and food or water deprivation (9 CFR 2.38f2ii)
must not be used to train, work, or handle dogs, although food and water
may be withheld for short periods when specified in an lACUC-approved
protocol (9 CFR 2.38f2ii).

SPECIAL CARE FOR ANIMAL MODELS

The remainder of this chapter deals with some common uses of labora-
tory dogs in which aspects of care vary from the general guidelines pro-
vided in previous chapters. It is not intended to present an exhaustive list

SPECIAL CONSIDERATIONS 79

of canine models that require special housing and husbandry, but rather to
provide the reader with different types of canine models that can serve as
examples of how housing and husbandry can be modified to achieve animal
well-being. The suggestions offered here are not to be construed as the
only ones possible. The committee recognizes that not every research pro-
cedure and circumstance can be anticipated, and it assumes that sound pro-
fessional judgment, good veterinary practices, and adherence to the spirit of
this guide will prevail in unusual situations.

The final subsection of this chapter introduces the reader to the tech-
nique of somatic cell gene therapy. Many disorders of dogs, like those of
humans, are caused by single-gene mutations. Scientists are working to
develop techniques to cure these disorders permanently by replacing mutant
genes with normal ones. For many reasons (see Chapter 2), the dog is an
ideal model for evaluating the safety and efficacy of gene therapy.

Aging

Clinical Features

Life expectancy and disease incidences vary among breeds of dogs;
therefore, it is not possible to state a specific age at which dogs become old.
Common laboratory dogs, such as beagles, begin some aging changes when
they are 8-10 years old. Such physical features as graying of the haircoat,
especially around the face, are often apparent as aging begins.

As dogs age, they tend to become less active and to exhibit such signs
of mental deterioration as poor recognition of caretakers, excessive sleep-
ing, and changes in personality. Senile plaques, similar to those found in
humans with senile dementias, have been reported in the brains of old dogs
(Wisniewski et al., 1970). Various forms of arthritis, spondylosis, and
degenerative joint disease are common and contribute to problems in mobil-
ity and to the apparent diminution of mental alertness. Older dogs might
decrease their daily food intake, become slow eaters, or become irregular in
their eating habits. Dental problems including periodontal disease, tooth
abscesses, and oral-nasal fistulas increase; the importance of these prob-
lems is probably underestimated (Tholen and Hoyt, 1983). Dogs more than
6 years old develop lenticular sclerosis, which results in a bluish appear-
ance within the pupil. Visual acuity decreases with age and is often associ-
ated with cataracts, secondary glaucoma, and other diseases (Fischer, 1989).
There is also apparent hearing loss.

Atrophy of the thyroid gland and an increased number of thyroid tu-
mors have been reported, and signs of hypothyroidism are common (Haley
et al, 1989; Milne and Hayes, 1981). Thyroid atrophy and the propensity
of older dogs to develop hypothermia might be related (B. A. Muggenburg,

80 DOGS: LABORATORY ANIMAL MANAGEMENT

Inhalation Toxicology Research Institute, Lovelace Biomedical and Envi-
ronmental Research Institute, Albuquerque, N.M., unpublished). A decreased
response to antigens and changes in lymphocyte function might indicate
that the older dog is less able to resist infectious diseases (Bice and Muggenburg,
1985). Some changes in common blood-cell measures and serum chemistry
become important when these are used for diagnosis (Lowseth et al., 1990a).
The incidence of neoplasia increases strikingly (MacVean et al., 1978); for
example, lung tumors, nearly unknown in young dogs, can reach an inci-
dence as high as 10 percent in dogs over 10 years old (Ogilive et al., 1989).
Pulmonary function decreases with age because of reduced lung volumes
and decreased elasticity (Mauderly and Hahn, 1982). Chronic renal dis-
eases often occur and require frequent monitoring. Chronic heart disease is
also fairly common, and clinical signs can appear suddenly in old dogs.

Husbandry and Veterinary Care

Housing and environment. Accommodation should be made for dogs
that have problems moving comfortably on floor grates or through guillo-
tine-like doors in kennel buildings. Because of their decreased mobility and
impaired thermoregulatory function, aging dogs with access to outdoor ar-
eas should be checked frequently to be certain that they are able to get
inside to escape the cold or heat. Automatic watering devices might be-
come difficult to use; for some old dogs, it might be necessary to switch to
water pans placed on the floor.

Nutrition. Differentiation between age-related and disease-caused changes
in eating habits might be difficult. It is important that animal-care person-
nel become familiar with and closely monitor daily eating habits of older
dogs. Frequent checking and recording of body weights can help in assess-
ing whether food intake is adequate. Changes in diet are sometimes dic-
tated by the clinical diagnosis of disease (e.g., a low-protein diet for chronic,
progressive renal disease and a low-sodium diet for chronic heart failure).

Physical characteristics of food can affect dental hygiene. Soft and wet
food fed over many years can contribute to dental disease. Feeding dry dog
food and providing hard objects for chewing can be helpful in the long-term
management of dental problems. Routine dental care, including the removal
of calculus and polishing, is essential.

Veterinary care. The extent of chronic disease problems in older dogs
requires more intensive veterinary care, extensive diagnostic investigations,
and good nursing. Dosages of some medications might have to be reduced,
because drugs are commonly metabolized more slowly in old than in young
adult dogs. Such drugs as digoxin should be monitored by measuring blood

SPECIAL CONSIDERATIONS

concentrations to decrease the risk of overdosing (De Rick et al., 1978). A
useful reference on geriatric veterinary medicine is Geriatrics and Geron-
tology (Goldston, 1989).

Reproduction

Bitches. Andersen and Simpson (1973) have described reproductive
senescence in beagle bitches. Intact bitches exhibit irregular estrous cycles,
accompanied by decreased fertility, and prolonged periods of anestrus. The
mortality rate is higher among puppies born to older bitches than among
puppies born to bitches less than 3 years old.

The most common pathologic condition of the uterus of aged bitches is
pyometra (Andersen and Simpson, 1973; Jarvinen, 1981; Whitney, 1967).
Vaginal fibromuscular polyps are also common (Andersen and Simpson,
1973). The age-specific incidence of mammary gland neoplasms in intact
beagle bitches continues to increase throughout life (Taylor et al., 1976).

Dogs. Aging dogs have testicular atrophy and often develop prostatic
hypertrophy and hyperplasia and have episodes of prostatitis (Lowseth et
al., 1990b). There are also metaplastic changes in the bladder (Lage et al.,
1989).

Cardiovascular Diseases
Congenital Heart Defects

Clinical Features

Dogs with hereditary cardiovascular malformations have been used to
investigate the role of genetic and embryologic factors in the cause and
pathogenesis of congenital heart defects, including hereditary patent ductus
arteriosus, conotruncal defects (e.g., ventricular septal defect, tetralogy of
Fallot, and persistent truncus arteriosus), discrete subaortic stenosis, and
pulmonary valve dyspiasia. Congenital heart defects in dogs have been
summarized by Buchanan (1992) and Eyster (1992). Table 6.1 describes
and lists the clinical signs of selected heart defects. Each of those defects is
transmitted as a lesion-specific genetic defect in one or more breeds, A
model for each defect has been developed at the University of Pennsylvania
School of Veterinary Medicine by selective breeding of affected dogs (Patterson,
1968), as follows: patent ductus arteriosus, toy and miniature poodles (Acker-
man et al., 1978; De Reeder et al., 1988; Gittenberger-de Groot et al., 1985;
Knight et al., 1973; Patterson et al., 1971); conotruncal defects, keeshonden
(Patterson et al., 1974, 1993; Van Mierop et al., 1977); discrete subaortic

DOGS: LABORATORY ANIMAL MANAGEMENT

TABLE 6.1 Selected Congenital Cardiac Defects in Dogs

Defect

Description

Clinical Signs

Patent ductus Failure of ductus arteriosus to

arteriosus close after birth. If pulmo-

nary vascular resistance is
low, blood flows through
ductus from left to right. Pul-
monary hypertension and left
ventricular hypertrophy result
unless ductus opening is small.
If ductus is large and pulmonary
vascular resistance is high, pul-
Imonary arterial pressure can
exceed aortic pressure, and blood
will flow from right to left, sending
venous blood into ascending aorta.

Conotruncal defects
Ventricular
septal
defect

Failure to complete formation of
the conotruncal septum results in
ventricular septal defects (VSDs)
of varied size, involving the lower
and middle portions of the crista
supraventricularis (Type I, sub-
arterial VSD). Pups with large
VSDs usually die from pulmonary
edema in the neonatal period.
Smaller VSDs are compatible with
long life unless complicated by
pulmonary hypertension and
congestive heart failure.

Tetralogy of Consists of pulmonic stenosis

Fallot (valvular, infundibular, or both),

conal ventricular septal defects,
dextroposition of aorta with
overriding of ventricular septum,
and right ventricular hypertrophy.
Some dogs have pulmonary valve
atresia (pseudo-truncus arteriosus).

Persistent Severe but rare anomaly. Complete

truncus failure of septation of conus and

arteriosus truncus regions, producing large

conal ventricular septal defect and
single arterial outlet vessel.

Vary with size of duct and
pulmonary vascular resistance
from subclinical to heart
failure. Early signs include
poor growth, coughing, and
dyspnea. Aneurysm can occur
at site of ductus arteriosus.
Polycythemia occurs in
cyanotic dogs with a large
patent ductus arteriosus
(PDA), pulmonary hyper-
tension, and right to left
blood flow through the PDA.

Vary with size of defect from
subclinical to signs of
respiratory and right-side
heart failure, including
cyanosis, dyspnea, weakness,
and anorexia.

Depend on severity of pul-
monic stenosis and ventric-
cular septal defect. Can
include decreased body
size, fatigue, cyanosis, and
secondary polycythemia.

Cyanosis and dyspnea. Dogs
rarely survive neonatal period.

SPECIAL CONSIDERATIONS

TABLE 6.1 Continued

Defect

Description

Clinical Signs

Discrete subaortic
stenosis

Pulmonary valve
dysplasia

Narrowing of left ventricular out-
flow tract, most commonly by
fibrous ring just below aortic
semilunar valves, with concomi-
tant obstruction of blood flow,
left ventricular hypertrophy,
and increased left ventricular
pressure.

Varies from mild thickening of
leaflets surrounding narrowed
pulmonary orifice to complete
fusion of leaflets and doming of
valve. Interferes with emptying
of right ventricle.

Vary with degree of stenosis
from asymptomatic to poor
growth, exercise intolerance,
syncope, ventricular
arrhythmias, pulmonary
edema, and sudden death.

Vary from asymptomatic to
dyspnea, fatigability, and
right-side heart failure.

stenosis, Newfoundlands (Patterson, 1984; Pyle et al., 1976); and pulmo-
nary valve dysplasia, beagles (Patterson, 1984; Patterson et al,, 1981). Conotruncal
defects in the keeshond breed are determined by the effect of a single major
gene defect (Patterson et al., 1993). Subaortic stenosis in Newfoundlands
also appears to be monogenic with variable expression (Patterson, 1984),
Patent ductus arteriosus and pulmonary valve dysplasia are inherited in a
non-Mendelian pattern.

Husbandry and Veterinary Care

Animals with cardiac defects often require exercise restriction to avoid
cyanosis and congestive heart failure. The need for restriction must be
decided for each dog on the basis of cardiac status. If the clinical manifes-
tations of severe defects (e.g., respiratory distress, severe cyanosis, and
congestive heart failure) cannot be relieved with appropriate surgical meth-
ods or cardiovascular drugs (e.g., cardiac glycosides and diuretics), the dog
should be humanely killed (see Chapter 5).

Reproduction

Only dogs with mild to moderate cardiac defects or those in which the
defects have been surgically corrected should be selected for breeding. Se-
verely affected dogs do not survive to breeding age, or they develop clinical
manifestations that preclude their use for reproduction (e.g., marked cyanosis

84 DOGS: LABORATORY ANIMAL MANAGEMENT

and congestive heart failure). Methods of modern clinical cardiology-
including auscultation, radiography, echocardiography, cardiac catheterization,
and angiocardiography are necessary for accurate diagnosis and evalua-
tion of the severity of defects in candidates for breeding. Therefore, appro-
priate facilities and equipment and personnel qualified to use such equip-
ment must be available before a breeding colony is established. Once it is
established, the health status of breeding stock and their offspring must be
carefully monitored.

Induced Heart Defects

Clinical Features

Many animal models of cardiac disease are surgically induced in physi-
ologically normal animals. Aims of the research protocol and humane con-
siderations must often be carefully balanced to ensure that the maximal
amount of information is derived from each animal.

Surgically induced models can be broadly divided into models of vol-
ume or pressure overload produced by creating valvular or interchamber
defects, models of ischemic injury, and models of arrhythmia (Gardner and
Johnson, 1988). Long-term management of these models can be difficult
because they are frequently on the verge of physiologic decompensation
and at risk of sudden death. Table 6.2 lists the signs of cardiac failure

TABLE 6.2 Clinical Signs of Heart Failure in Dogs

Type of Heart Failure Clinical Signs

Left " Side Exercise tolerance decreases. Inappropriate dyspnea folto^T

exercise. Pulmonary venous pressure increases, initially
causing pulmonary and bronchial congestion and
reflexogenic bronchoconstriction. Repetitive coughing
follows exercise. Orthopnea, with a reluctance to lie
down; restlessness at night; and paroxysmal dyspnea are
common. In severe failure, pulmonary edema, severe

R - h , .. dyspnea at rest, and rales on auscultation become evident.

g Systemic venous congestion occurs with engorgement of

jugular veins. Liver and spleen are enlarged and often
palpable. Fluid retention is usually first manifested as
ascites; subcutantous edema, hydrothorax, or
hydropericardium can follow. Disturbances of

Generalized gastrointestinal function, with diarrhea, can occur.

Signs of both left- and right-side failure occur.

SPECIAL CONSIDERATIONS 85

Husbandry and Veterinary Care

The management of chronic dog models of induced heart failure is most
successful if the approach used is interdisciplinary, involving cardiologists,
surgeons, and veterinary-care staff. Goals of long-term management in-
clude identifying potential complications, selecting therapeutic regimens,
and developing long-term monitoring protocols. The following general guidelines
should be tailored to the type of disorder induced, the dogs' well-being, and
the goals of the research protocol.

Postoperative care. Postoperative care depends on the type of heart
disease induced. Medical management should continue after successful
recovery from surgery because a specific surgical protocol does not always
produce a physiologically consistent model. Some dogs achieve a stable,
compensated postoperative condition; others undergoing the same proce-
dure develop signs of acute heart failure immediately after surgery.

Careful monitoring on the days after surgery is critical. Meticulous
physical examinations should be performed on physiologically stable dogs
at least once a day until they have recovered from surgery. Physiologically
unstable dogs should be examined more often. Vital signs should be moni-
tored, and particular attention should be given to physical findings related
to the cardiovascular system. Mucous membrane color, capillary-refill time,
and temperature of extremities can be abnormal if peripheral perfusion is
seriously impaired. The pulse quality of the femoral artery can be used to
assess systemic perfusion. Auscultation should be used to detect abnormal
cardiac sounds, and electrocardiography should be performed to diagnose
arrhythmias. Assessment of respiratory rate and depth should be combined
with careful auscultation of all lung fields to detect early signs of pulmo-
nary complications. Echocardiography, if available, can be used to evaluate
cardiac function and contractility.

Good nursing care is important. Special diets, such as canned dog food
or dry food mixed with chicken broth, can be offered to encourage food
intake. Ideally, dogs should be housed in a dedicated recovery room and
returned to the regular housing area only when they are physiologically
stable and have recovered fully from surgery. Decreased exercise tolerance
secondary to diminished cardiac reserve might affect the extent of activity
that a dog can withstand.

Complications. Potential complications associated with surgical and
catheterization procedures should be anticipated, including infection of the
operative site, bacteremia, and endocarditis. Dogs at high risk for compli-
cations are the ones that undergo serial catheterization procedures and those
with bioimplants, such as prosthetic valves and pacemakers (Dougherty,

86 DOGS: LABORATORY ANIMAL MANAGEMENT

1986). Baseline monitoring should include scheduled physical examina-
tions and complete blood counts (CBCs). A blood culture should be sub-
mitted to the laboratory for any animal with a persistent fever or an inter-
mittently increased temperature. If infection is suspected, a broad-spectrum
antibiotic, such as one of the cephalosporins, should be administered pend-
ing receipt of culture and sensitivity results.

Banding of the great vessels with various materials is a standard proce-
dure for producing volume- and pressure-overload models of ventricular
hypertrophy, coarctation of the aorta, and obstruction of right ventricular
outflow. Vessel erosion caused by the material used (Gardner and Johnson,
1988) and hemorrhage secondary to banding procedures are common com-
plications that should be included in the differential diagnosis of any banded
animal that suffers an acute onset of lethargy, paleness of the mucous mem-
branes, or dyspnea. Those are also clinical signs of heart failure, so it is
important to perform auscultation of the chest and suitable diagnostic tests,
such as radiography or thoracentesis, to make an accurate diagnosis. A dog
that is hemorrhaging should be euthanatized.

Surgical procedures used to induce cardiac disease invariably cause
disruption of the endothelium and put the dogs at risk for thrombosis and
embolism. Dogs undergoing cardiac catheterization or surgery of the car-
diac valves are at greatest risk. Clinical signs reflect the organs involved.

Long-term monitoring. In a study of extended duration, assessment of
each dog's general health and cardiovascular system should be continuous.
The type and frequency of examinations will depend on whether the model
is physiologically stable or unstable. For example, a dog with induced
mitral regurgitation, which is defined as a 50 percent reduction in forward
stroke volume and a pulmonary capillary wedge pressure of 20 mm Hg, can
develop life-threatening pulmonary edema (Nakano et al., 1991; Swindle et
al., 1991). Frequent monitoring and auscultation are required to detect
early signs of respiratory compromise so that the dog will not die before
therapy can be initiated or the dog can be studied. Similarly, a dog with
induced right ventricular pressure overload requires frequent monitoring
because decreased coronary blood flow can lead to acute right-side heart
failure (Fixler et al., 1973; Vlahakes et al., 1981). Conversely, a stable
model of left ventricular hypertrophy can be produced in 8-week-old pups
by aortic banding, which causes a systolic pressure gradient of 15-20 mm
Hg (O'Kane et al., 1973). Dogs with induced tricuspid valve insufficiency
can tolerate increased venous pressure and a slight reduction in cardiac
output for years, although some develop ascites and reduced serum albumin
(Arbulu et aL, 1975). These models require less frequent monitoring.

Equipment. Follow-up care and monitoring require appropriate equip-

SPECIAL CONSIDERATIONS " 87

ment and laboratory support for obtaining CBCs, blood cultures, serum
chemistry profiles, and blood-gas analyses. Electrocardiography and
echocardiography should be available for assessing cardiac rhythm and function,
respectively. Echocardiography is also a useful noninvasive method for
monitoring changes in cardiac wall thickness, cardiac motion, and chamber
size as cardiac disease progresses. A cardiac catheterization laboratory
should be available for performing hemodynamic and angiographic studies.

Pharmacologic therapy. Pharmacologic management of dogs that de-
velop complications or clinical signs of heart failure must be coordinated
between the veterinary unit and the investigator to prevent the administra-
tion of medications that could compromise the scientific aims of the study.
Diuretics can be used to treat pulmonary edema and reduce plasma volume,
but their effects on serum electrolytes and the reduction of venous return
and cardiac output should be considered. Vasodilators, calcium antago-
nists, (3-blocking drugs, and positive inotropic agents should be available
for managing acute clinical events; however, long-term use of these drugs is
usually contraindicated because of their effects on the disease process being
studied (Bonagura, 1986; Swindle et al., 1991).

Hypertension

Clinical Features

To provide proper care for hypertensive dogs and to avoid inappropri-
ate treatment that can be detrimental to the dogs and compromise the study,
it is necessary to have a full understanding of the pathophysiology of hyper-
tension and of the specific method that is used to induce it. Generally,
hypertension in dogs is induced by constricting the renal artery. The result-
ing reduction in renal perfusion causes systemic arterial pressure and re-
nal arterial pressure distal to the constriction to rise enough to maintain
renal function. A discussion of the relationship between renal function and
the long-term control of blood pressure can be found in any standard physi-
ology textbook (e.g., Guyton, 1991).

Two methods are most commonly used to induce renal vascular hyper-
tension: partial constriction of one renal artery (the 2-kidney, 1-clip method)
and unilateral nephrectomy and partial constriction of the remaining renal
artery (the 1 -kidney, 1-clip method). Both those methods produce what is
called Goldblatt hypertension, but the mechanisms responsible for the hy-
pertension are different. The 2-kidney, 1-clip model depends more heavily
on the renin-angiotensin system than the 1 -kidney, 1-clip model and re-
sponds to acute treatment with angiotensin-converting enzyme (ACE) in-
hibitors, which block the conversion of angiotensin I to angiotensin II. The

88 DOGS: LABORATORY ANIMAL MANAGEMENT

1 -kidney, 1-clip model requires chronic treatment with ACE inhibitors to
lower blood pressure. The reason for that difference is described in detail
by Guyton (1991).

The greatest success in producing hypertension while reducing the inci-
dence of malignant hypertension and renal failure is achieved by reducing
renal arterial flow by exactly 50 percent. Renal blood flow is usually
measured when the arterial clamp (Goldblatt clamp) is adjusted during sur-
gery; this obviates later surgery to readjust the degree of constriction. Methods
have been developed for measuring renal blood flow chronically and adjust-
ing the renal artery clamp (Ferrario et al., 1971), and more recently a tech-
nique has been described for producing hypertension reliably by gradually
constricting the renal artery with constrictors fabricated of ameroid, a hydroscopic
material made of compressed casein cured in formalin (Ben et al., 1984;
Brooks and Fredrickson, 1992).

Other methods that have been used for inducing hypertension include a
2-kidney, 2-clip model in which Goldblatt clamps or ameroid constrictors
are applied to both renal arteries; wrapping of one or both kidneys with silk
or cellophane; a combination of unilateral nephrectomy and wrapping of
one kidney; and placing sutures in a figure 8 configuration on the surface of
one or both kidneys (the Grollman model). The creation of hypertension
with deoxycorticosterone acetate (DOCA) and common salt has not been as
successful in dogs as it has in rats, because dogs are reluctant to eat a high-
salt diet or drink a saline solution. However, moderate hypertension in
dogs can be achieved with DOCA administration alone. A colony of spon-
taneously hypertensive dogs has been described (Bovee et al., 1986).

Husbandry and Veterinary Care

Proper care of hypertensive dogs involves the following:

careful design and establishment of the hypertensive model to pro-
duce stable hypertension;

routine evaluation of renal function;

regular and frequent monitoring of blood pressure;

regular monitoring of the retinas;

appropriate treatment with antihypertensives when required; and

careful husbandry.

Evaluation of renal function. Routine evaluation of renal function is
essential because renal failure is a common complication in dogs with ex-
perimental hypertension. Renal failure can be caused by too much constric-
tion of the renal artery, a rapid increase in both systolic and diastolic pres-
sures (malignant hypertension), or the inappropriate use of antihypertensives.

SPECIAL CONSIDERATIONS 89

Evaluation of renal function is especially important with use of the 1 -kid-
ney, 1-clip and 2-kidney, 2-clip models (which cause the most severe hy-
pertension) and during antihypertensive therapy. In hypertensive dogs, re-
nal function is compromised to such an extent that blood pressure must be
raised to maintain sodium balance. If antihypertensive therapy lowers blood
pressure too much, acute renal failure will ensue.

The most reliable and easily measured indicators of renal function are
serum creatinine concentration and blood urea nitrogen (BUN). Although
they depend somewhat on the type of assay, normal serum creatinine for the
dog ranges between 0.4 and 1.3 mg/dL and BUN between 10 and 25 mg/dL.
Serum creatinine and BUN should be determined in each dog before hyper-
tension is induced to avoid using dogs with already-compromised renal
function. In Goldblatt hypertensive models, serum creatinine should be
determined daily for the first 5 days after surgery and twice a week thereaf-
ter. If ameroid constrictors are used, daily evaluations should continue
through the second week after surgery because it takes 4-5 days for ameroid
constrictors to reach maximal constriction. In models in which hyperten-
sion is not as severe, such as the 2-kidney, 1-clip and 1-kidney, 1-wrapped
hypertensive models, renal function is less likely to be impaired, and serum
creatinine concentration and BUN might not be increased, but they should
be evaluated at least once during the 10-day postoperative period.

If renal-function tests show signs of renal failure, corrective action
should be taken. Too-severe constriction of the renal artery can be cor-
rected surgically, or the study can be terminated by euthanatizing the ani-
mal. Renal failure caused by lowering blood pressure to below the renal
autoregulatory range should be corrected by reducing the dose of the
antihypertensive drug to a point that allows blood pressure to remain high
enough to maintain renal function. Malignant hypertension can be treated
with antihypertensives and reduced salt intake (Ross, 1989; see below).

Measurement of arterial blood pressure. Blood pressure should be
determined routinely after surgery. It can be done with indirect methods,
such as placing a pressure cuff at the base of the tail (Petersen et al., 1988)
or above the hock, or with direct methods, such as chronic implantation of
arterial catheters or acute femoral arterial catheterization. To avoid compli-
cations associated with exteriorized catheters, some investigators now use
methods that do not require exteriorized components, such as a Vascular
Access Port (Access Technologies, Skokie, 111.) (Mann et al., 1987), or
chronic instrumentation, such as constriction of the carotid loop (Brooks et
al., 1991). In addition, improved telemetric monitoring (Lange et al., 1991)
has the potential to allow continuous monitoring of blood pressure over a
number of days or weeks.

It is important to establish a baseline blood pressure before inducing

DOGS: LABORATORY ANIMAL MANAGEMENT

hypertension. Measuring blood pressure several times permits the dog to
become accustomed to the monitoring technique and thereby avoids in-
creases in blood pressure caused by stress. Some investigators measure
blood pressure indirectly (e.g., with the tailcuff method) before surgery and
use more direct methods later. That is done in recognition that indirect
methods can lead to a deviation of up to 10 mm Hg from true arterial
pressure. Normal systolic blood pressure ranges from 112 to 142 mm Hg;
normal diastolic pressure from 56 to 110 mg Hg. Measurements greater
than 160/95 indicate hypertension.

Treatment for hypertension. When induced correctly, surgically cre-
ated hypertension is sustained and has few complications. If necessary,
hypertensive dogs can be maintained on special diets (see below) and given
diuretics or other antihypertensive drugs when needed. Some drugs readily
available for treatment of hypertensive dogs are listed in Table 6.3.

Malignant hypertension must be diagnosed quickly and treated aggres-
sively. The most striking clinical sign of malignant hypertension can be
blindness caused by retinal detachment, which is usually preceded by reti-
nal hemorrhage, dilation of retinal vessels, and subretinal edema. The dogs
do not appear to be in pain but often bump into walls and might become
disoriented or sit quietly in their pens or cages. Diagnosis can easily be
confirmed with an ophthalmologic examination. If blood pressure can be
controlled and retinal disinsertion (detachment from the ora ciliaris retinae)

TABLE 6.3 Drugs Available for the Oral Treatment of Hypertension in
Dogs*

Generic Name

Dosage,
mg/kg

Frequency of
Administration

Class

Chlorothiazide

20-40

Every 12 hr or daily

Diuretic

Hydrochlorothiazide
Furosemide^

2-4
2-4

Every 12 hr or daily
Every 8-12 hr

Diuretic
Diuretic

Propranolol

0.25-0.5

Every 8 hr

p-Adrenergic antagonist

Hydralazine

1-3

Every 12 hr

Vasodilator

Prazosin

0.25-2

Every 8 hr

Vasodilator

VerapamiF

1-2

Every 8 hr

Vasodilator; calcium-

channel blocker

Captopril

0.5-1

Every 8-12 hr

Angiotensin-converting

enzyme inhibitor

fl Adapted from Ross, 1989; printed with permission of the author and W. B. Saunders,
Philadelphia, Pennsylvania.

^Can also be given intramuscularly or intravenously at 2-4 mg/kg.
c Can also be given intravenously at 0.05-0.15 mg/kg.

SPECIAL CONSIDERATIONS py

does not occur, some vision might be restored in 2-3 weeks. Malignant
hypertension often responds well to treatment with ACE inhibitors. Diuret-
ics can also be administered if care is taken to avoid a precipitous drop in
renal blood flow. Vasodilators can be used with caution. If the cause of the
malignant hypertension is overconstriction of the renal artery, ACE inhibi-
tors can be used to stabilize the dog while the stricture is surgically cor-
rected.

Husbandry. Routine care of hypertensive dogs must include a consid-
eration of diet because both salt intake and protein intake will affect blood
pressure and renal function. A high salt intake will exacerbate hyperten-
sion, and a high protein intake might accelerate the loss of renal function.
To avoid unintended changes in diet that could compromise their dogs and
studies, investigators, veterinarians, and others caring for hypertensive dogs
should establish dietary requirements before beginning studies.

For dogs with hypertension and renal failure, the diet should contain
0.1-0.3 percent sodium on a dry-weight basis or 10-40 mg/kg per day (5-20
mg/lb per day) (Ross, 1989). Low-protein diets (less than 15 percent) that
are also low in sodium (e.g., K/D, Hill's Pet Products, Inc., Topeka, Kan-
sas) are available and should be fed in adequate amounts generally 1 can
or 2 cups of dry food for each 10 kg (20 Ib) of presurgical body weight.
The protein content of some commercially available diets might be too low
to maintain ideal body weight, but diets that combine a higher protein con-
tent with a lower sodium content are available (e.g., R/D, Hill's Pet Prod-
ucts, Inc., Topeka, Kansas). As in any dog model, following the body
weight of an animal regularly is a good way to monitor the animal's overall
health.

There is usually no reason to restrict primary enclosure size for hypertensive
dogs. Whether they should be exempted from an exercise program depends
on their postoperative course. If the hypertensive condition stabilizes and
there are no complications, exemption from exercise should not be neces-
sary. Blood pressure is known to increase in stressful conditions; therefore,
it is important that such conditions be avoided (e.g., dogs that are housed or
exercised in pairs or groups should be monitored to ensure that they are
compatible).

Ehlers-Danlos Syndrome

Clinical Features

Ehlers-Danlos syndrome type 1 is an autosomal dominant condition of
humans for which there are analogues in dogs and other mammals (Hegreberg
et al., 1969, 1970). The disease is caused by a defect in metabolism of

92 DOGS: LABORATORY ANIMAL MANAGEMENT

dermal collagen that results in a skin tensile strength less than 10 percent of
normal. Fibrous tissue and bone are subclinically affected in some cases
(Minor et al., 1987). Multiple lacerations are often observed. The hyperextensible
skin can cause superior entropion, inferior ectropion, or both.

Husbandry and Veterinary Care

The extreme fragility of the skin must be considered in managing dogs
with this syndrome. Affected dogs should be housed singly in smooth-
surfaced pens of glass, concrete, or sheet steel. Automatic watering valves
and other projections should be avoided. The dogs' nails should be kept
trimmed. Some dogs might have to wear Elizabethan collars for extended
periods to prevent self-inflicted wounds. Dogs should be given opportuni-
ties for exercise, either singly or in small groups, by being released under
supervision into an exercise pen or room that is free of sharp projections.
Leash-walking should be avoided.

Wound management is relatively simple. Wounds tend to heal well,
possibly because hyperextensible skin places little tension on wounds. Cut-
ting suture needles and single-stranded nylon suture material can tear through
the skin, but tapered needles and braided sutures, such as those of polygalactin
910 (Vicryl), are well tolerated. It is important to avoid placing too much
tension along a single suture line. Hygromas and hematomas, which can
become large under loose skin, can be encountered, either as sequelae to
lacerations or as primary events. Adhesive tape should never be applied
directly to the skin or fur during bandaging because it can tear the skin
when the bandage is removed. Entropion and ectropion can be corrected
surgically; however, repeated correction might be necessary.

Reproduction

All affected dogs appear to be heterozygotes; affected homozygotes
probably die in utero. To increase fertility, to avoid injury of affected
animals, and to prevent conception of homozygotes, it is preferable to select
normal bitches and affected males for breeding and to use artificial insemi-
nation. Heterozygous affected pups can be identified at birth by the fragil-
ity and hyperextensibility of their skin, as can heterozygous fetuses in late
gestation.

SPECIAL CONSIDERATIONS

Endocrinologic Diseases

Clinical Features

Endocrinopathies in the dog pose diagnostic and therapeutic challenges
because they are complicated physiologic derangements that often involve
multiple organ systems. An endocrinopathy might be a desired element of
an experimental design or simply a spontaneous random occurrence that
would be expected in any canine population. Table 6.4 lists the major
endocrinopathies that have been documented in dogs. Discussions in this
section are limited to endocrinopathies that either are induced in experimen-
tal animals or are undesired results of management procedures or investiga-
tional protocols. Hypothyroidism and hyperadrenocorticism (Cushing's disease),
two major endocrinopathies often seen in clinical veterinary practice, are
not discussed here but are well described in the veterinary medical literature
(e.g., Capen and Martin, 1989; Chester, 1987, Drazner, 1987a; Feldman,
1989; Hsu and Crump, 1989; Peterson and Ferguson, 1989). A brief review
of disorders of calcium metabolism is included because hypocalcemia caused
by iatrogenic hypoparathyroidism occasionally occurs in a research setting,
and hypercalcemia is often mistakenly attributed to parathyroid dysfunc-
tion.

TABLE 6.4 Selected Endocrine Disorders in Dogs
Affected Organ Diseases

Adrenal cortex Hyperadrenocorticism

Hypoadrenocorticism

Adrenal medulla Pheochromocytoma

Pancreas Diabetes mellitus

Gastrinoma

Parathyroid Hyperparathyroidism

Hypoparathyroidism

Pituitary Acromegaly

Diabetes insipidus
Hypopituitarism

Thyroid Hyperthyroidism

Hypothyroidism

Multiple glands Hyperlipidemia

Hypoglycemia

94 DOGS: LABORATORY ANIMAL MANAGEMENT

TABLE 6.5 Common Clinical Signs of Selected Canine Endocrinopathies

Endocrinopathy Common Clinical Signs

Diabetes mellitus Hyperglycemia, polydipsia, polyuria, glycosuria, increased food

consumption but loss of weight, bilateral cataract develop-
ment, weakness

Hypoadrenocorticism Weakness, vomiting, diarrhea, bradycardia, acute collapse

Acromegaly Respiratory stridor, increased interdental spaces, prominent skin

folds, abdominal enlargement, fatigue

Hypercalcemia Mental dullness; muscular weakness; tachycardia; upper

gastrointestinal signs, including anorexia, nausea, and
vomiting; signs of renal disease, including nephrocalcinosis,
renal calculi, and secondary renal failure

Hypocalcemia Muscle tremors, tetany, seizures

Common clinical signs of the endocrinopathies to be discussed are listed
in Table 6.5. They range from very subtle changes to acute crises. Most
are nonspecific and can also be seen in various nonendocrine disorders.
Detailed discussions of endocrinopathies can be found in the veterinary
medical literature (e.g., Drazner, 1987b; Ettinger, 1989; Feldman and Nelson,
1987; McDonald and Pineda, 1989; Morgan, 1992).

Husbandry and Veterinary Care

Procedures for managing dogs with endocrinopathies are dictated by
both the experimental design and the animals' welfare.

Diabetes mellitus. Diabetes mellitus in the dog is a recognized sponta-
neously occurring model (Kramer, 1981), and the disease is readily induced
either by chemical ablation of the pancreatic (3-cells or by total pancreatectomy
(Mordes and Rossini, 1985). Frequent monitoring is mandatory for the
successful management of dogs with diabetes mellitus. Daily measure-
ments, before the first meal of the day and 6-12 hours later, are required to
stabilize and control blood glucose in diabetic dogs. The second glucose
measurement can be eliminated only when the afternoon blood glucose of
an individual dog is consistent from day to day and the insulin requirement
for that dog is well established. Blood glucose monitoring should begin
after initial administration of diabetogenic chemicals or during the first 24
hours after pancreatectomy. Fasting blood glucose, as measured by the
plasma or serum glucose oxidase method, ranges from 65-118 mg/dL (3.6-
6.5 mmol/L) in normal adult dogs (Kaneko, 1989).

A number of insulin preparations can be used either singly or in combi-
nation in dogs: regular, NPH, lente, and ultralente. Unit doses and prepara-

SPECIAL CONSIDERATIONS

tion types must be determined for and adjusted to the response of each dog.
Insulin should be started at a dose of 1 U/kg per day injected subcutane-
ously at the time of feeding the first meal of the day. Daily proportions of
each preparation included in a therapeutic regimen are determined by trial
and error as guided by the results of serial blood glucose measurements.
Detailed information on dosage and characteristics of various insulin prepa-
rations is available (Nelson, 1989; Schaer, 1992).

In addition to insulin administration, stresses from environmental and
experimental manipulation, exercise, concurrent disease, estrus, and changes
in food and water intake can cause profound fluctuations in blood glucose
concentrations. Blood glucose can be manipulated by adjusting insulin types
and dosages. As a general rule, it is preferable to have a slightly hyperglycemic
dog rather than a hypoglycemic one because of the potentially disastrous
results of a hypoglycemic crisis. If such a crisis occurs, it should be treated
with intravenous dextrose and supportive care (Kirk and Bistner, 1985).
Supplemental glucose can be given orally if the dog is able to swallow.
Obviously, a necessary follow-up includes reviewing and adjusting the in-
sulin dosage and the ratio of short- to long-acting insulin preparations given.

The amount of food fed to each diabetic dog should be standardized at
what is necessary to maintain its optimal body weight. The same amount
should be fed each day. Once an eating pattern (amount of food eaten and
time required for meal consumption) is established for a given dog, its
appetite can be used as an indicator of general well-being.

In pancreatectomized dogs, it is necessary to compensate for lost pan-
creatic exocrine function. That can be accomplished by adding a commer-
cially available digestive enzyme to the food. Some dogs find the product
unpalatable, but it is generally accepted if it is mixed with canned food.

Diabetic dogs can be maintained for long periods, but sequelae of dia-
betes mellitus including neuropathy, immune system compromise, and de-
layed healing do occur, and a shorter than normal life span should be
expected.

Hypoadrenocorticism. The canine model of hypoadrenocorticism (Addison's
disease) is a classic model in biomedical research (Brown-Sequard, 1856),
Hypoadrenocorticism can be induced in dogs by administering the drug
mitotane, 1 which chemically ablates the adrenal cortex (Nelson and Woodard,
1949). During induction, a presumptive diagnosis can be made by monitor-
ing changes in serum electrolytes, specifically sodium and potassium. The
normal ranges of sodium and potassium concentrations in dog serum are

1 Chemical name, l,l-dichloro-2-(<?-chlorophenyl)-2-(p-chIorophenyl) ethane; trivial name,
0,p'-DDD; brand name, Lysodren.

96 DOGS: LABORATORY ANIMAL MANAGEMENT

140-155 mEq/L and 3.7-5.8 mEq/L, respectively (Carlson, 1989). In dogs
with hypoadrenocorticism, the sodium-to-potassium ratio is decreased to
less than 27:1 (Schrader, 1988), although this hyperkalemia is not pathognomonic.
The adrenal corticotropic hormone stimulation test is required for definitive
diagnosis (Nichols and Peterson, 1992). In a crisis, resuscitation requires
recognizing the problem, intravenously administering 0.9 percent saline so-
lution, replacing glucocorticoids and mineralocorticoids, and possibly pro-
viding therapy for hyperkalemia. Long-term maintenance entails glucocor-
ticoid (cortisone) administration, mineralocorticoid supplementation with
9-fluorohydrocortisone acetate, 2 and the addition of sodium chloride to the
diet Electrolytes should be monitored at least weekly once stabilization is
achieved. Environmental and experimental stresses and alterations in water
and food availability can have substantial effects on electrolyte balance and
homeostasis. Additional glucocorticoid (increased by a factor of 2-10) should
be administered during periods of stress.

Acromegaly. Acromegaly can be iatrogenically induced in bitches when
progesterone is given to prevent estrous cycling (Eigenmann, 1985, 1989).
It can also be secondary to increased production of progesterone during
diestrus. Progesterone induces acromegaly by increasing the production of
growth hormone in the anterior pituitary gland. The excessive release of
growth hormone can also induce a "pituitary diabetes" that can be difficult
to control with insulin. Cessation of progesterone administration or spaying
will reverse acromegalic changes.

Calcium derangements. Although disorders of the parathyroid glands
are usually suspected when hypercalcemia or hypocalcemia is present, the
calcium abnormality is more often associated with other conditions, includ-
ing pseudohyperparathyroidism, the most common cause of hypercalcemia
(Feldman and Nelson, 1987); hypoadrenocorticism; renal failure; bone le-
sions; and hypervitaminosis D. Primary hyperparathyroidism in the dog is
rare. Pseudohyperparathyroidism (hypercalcemia of malignancy) is a
paraneoplastic syndrome that has been recognized in dogs with lymphosar-
coma, adenocarcinoma of the anal apocrine glands, multiple myeloma,
osteosarcoma, and other neoplasms (Meuten et al., 1982, 1986). Signs of
hypercalcemia are not always overt, and treatment should be directed to-
ward the underlying cause.

Causes of hypocalcemia include calcium imbalance during lactation,
renal disease, acute pancreatitis, intestinal malabsorption, hypoalbuminemia,
and primary hypoparathyroidism (idiopathic or iatrogenic). latrogenic

2 Brand name, Florinef.

SPECIAL CONSIDERATIONS

hypoparathyroidism is associated with inadvertent damage or removal of
the parathyroid glands and is an important consideration in research set-
tings. Surgery involving the ventral neck area or the laryngeal-tracheal area
or removal of the thyroid glands carries an increased risk of complications
related to parathyroid function. Treatment includes calcium replacement
and appropriate management of the precipitating disorder.

Hematologic Disorders

Clinical Features

Canine models of human hematologic disorders have been reviewed
(Dodds, 1988, 1989, 1992; Hall and Giger, 1992; Harvey, 1989; Kaneko,
1987; Knoll, 1992). Clinical signs of some of these disorders are listed in
Table 6.6.

TABLE 6.6
Dogs

Inheritance and Signs of Selected Hematologic Disorders in

Disorder

Inheritance

Clinical signs

Hemophilia A

Hemophilia B
(Christmas disease)

von Willebrand's
disease type I

X-linked Low factor VIII coagulant activity but normal or

increased von Willebrand factor antigen
concentrations; spontaneous bleeding diathesis
of varied severity, depending on factor VIII
activity; severely affected dogs often exhibit
spontaneous hemarthroses and large joints.
The most common severe inherited bleeding
disease. Recognized in most purebreds and in
mongrels.

X-linked Deficiency of factor IX activity; signs similar to

those of hemophilia A. Recognized in 17
breeds.

Autosomal Variable deficiency of von Willebrand factor;

incompletely factor VIII activity might be reduced; and
dominant prolonged bleeding time; moderately severe

bleeding diathesis of mucosal surfaces. Signs
are exacerbated by stress, hypothyroidism,
intercurrent disease, trauma, and surgery.
Recognized in more than 50 breeds.

continued on next page

DOGS: LABORATORY ANIMAL MANAGEMENT

TABLE 6.6 Continued

Disorder

Inheritance Clinical signs

von Willebrand's
disease type III

Factor X deficiency

Thrombopathia

Cyclic hematopoiesis

Pyruvate kinase
deficiency

Erythrocyte
phosphofructokinase
deficiency

Autosomal Severe deficiency of von Willebrand factor;

recessive factor VIII activity is usually low; indefinitely

prolonged bleeding time; mucosal surface
bleeding diathesis, which can be severe and is
exacerbated by stress, hypothyroidism, trauma,
surgery, and intercurrent disease. Recognized
in Chesapeake Bay retrievers, Scottish terriers,
and Shetland sheepdogs.

Autosomal Homozygotes are stillborn or die shortly

incompletely after birth; affected pups might live for
dominant up to 2 weeks and then die of massive internal

bleeding; young adults can also exhibit life-
threatening hemorrhage, but signs in mature
adults are usually mild and confined to
mucosal surfaces. Found only in one large
family of cocker spaniels.

Autosomal Affected dogs can have no clinical signs or

show increased bleeding tendency that can be
exacerbated by trauma or surgery. Found in
basset hounds and otterhounds.

Autosomal Regularly occurring interruptions of bone

recessive marrow hematopoiesis with loss of neutrophils

from peripheral blood; during these periods,
dogs exhibit fever, enteritis, keratitis,
pneumonia, and skin infections; infections can
become life-threatening if not treated. Found
in gray collies.

Autosomal Affected dogs exhibit severe anemia with

recessive reticulocytosis, macrocytosis, and

polychromasia; hyperbilirubinemia;
splenomegaly with extramedullary
hematopoiesis; and decreased red cell survival.
Found in basenjis, beagles, and cairn terriers.

Autosomal Persistent compensated hemolytic anemia

recessive with episodes of intravascular hemolysis,

hemoglobinuria, and fever associated with
stress or exercise; hemolytic crises follow
hyperventilation-induced alkalemia; red cells
of affected dogs are extremely alkaline and
fragile in vitro. Found in English springer
spaniels.

SPECIAL CONSIDERATIONS 99

Husbandry and Veterinary Care

Bleeding disorders. Dogs with congenital and acquired bleeding disor-
ders require special housing to minimize the risk of spontaneous or injury-
induced bleeding. This is important not only for the animals' welfare, but
also for experimental reasons. The basal state of animals that experience
repetitive bleeding can be altered by the physiologic stress that such bleed-
ing causes and, if bleeding is severe enough to require transfusions, by
repeated exposure to homologous plasma proteins and blood cells. That is
of particular concern for dogs with severe disorders, such as hemophilia.

Dogs with bleeding disorders should be housed in enclosures that have
smooth sides and fronts with smooth vertical or cross-hatched bars. It is
not advisable to use materials that can be climbed (e.g., chain-link fencing)
because dogs with bleeding disorders can suffer foot injuries caused by
weight-bearing pressure between the toes. Enclosure size is also important.
To prevent injury, affected animals should have sufficient space to move
about freely but not enough to permit vigorous exercise if they become
excited. Enclosures should be square or oblong; injury is more likely to
occur in a long, narrow run, especially in dogs with long tails, which during
wagging can be traumatized by hitting against the sides. Experience has
shown that for dogs weighing from 13.6-36.3 kg (30-80 Ib), primary hous-
ing measuring about 4 x 6 f t (1.22 x 1.83 m) or 5 x 5 f t (1.52 X 1.52 m)
minimizes the risk of injury.

Severely affected dogs should be housed individually because the risk
of injury in playing with other dogs is substantial. To provide socialization,
it is advisable to construct pens that allow visual contact between dogs; this
can be achieved by building pens across an aisle from or perpendicular to
each other. Partitions between the runs should be solid for the first 4 ft
(1.22 m) in height to prevent injury caused by dogs in adjacent pens playing
or fighting through the partition, and the seam with the floor should be
smooth.

To avoid foot-pad abrasions, nonslip flooring should not be too rough.
A poured rubberized flooring with a small amount of sand added to the last
coat should create enough friction to prevent sliding. Nontoxic bedding
(e.g., shredded newspaper or shavings) can be used to minimize injuries if
sliding does occur. English rubber coits or tennis balls can be used to
provide environmental enrichment.

Special arrangements are required for feeding and watering. Automatic
watering devices are generally not recommended because the spigots can
cause mouth injuries, and bleeding from such injuries is usually difficult to
control. It is better to use large water buckets anchored to the sides or
fronts of the pens. Dry food should be softened before feeding and supple-

100 DOGS: LABORATORY ANIMAL MANAGEMENT

mented with good-quality canned or cooked meat. A hematinic can be
added to the food for conditioning. Hard biscuits should not be fed.

Bleeding from small surface injuries to the gums or nose or from toe-
nails that are cut too short can be stopped by using sealant materials, such
as Nexaband glue (Tri-Point Medical, LP, Raleigh, N.C.). Bleeding toe-
nails can also be packed with styptic powder, and the soft rubber end cap
from an intravenous set or catheter can be wedged tightly over the nail. If
necessary, the foot can be bandaged; this supplies enough local pressure to
control the bleeding. For animals that experience severe bleeding episodes,
transfusion is the treatment of choice. Fresh-frozen plasma, plasma concen-
trates, platelet concentrates, or packed red cells should be given as required
for the specific disorder. Details of management and treatment are summa-
rized elsewhere (Dodds, 1989, 1992).

Another management procedure to keep animals healthy and reduce
bleeding risk is prophylactic dentistry, which must be performed very care-
fully to avoid injury to the gums. Booster vaccinations should not be given
during bleeding episodes because they create a transient platelet deficit
(Dodds, 1992). In addition, dogs are at increased risk for bleeding episodes
for 10-14 days after vaccinations. Affected females sometimes bleed exces-
sively both during estrus and during the 30-40 days beforehand when estro-
gen concentrations are elevated.

Cyclic hematopoiesis. Colonies of grey collies with cyclic hematopoie-
sis (formerly called cyclic neutropenia) have special requirements because
they are susceptible to recurring infections and anemia (Knoll, 1992). They
have a cyclic, profound drop in all their blood-cell classes, although the
numbers of each cell type rise and fall at different times. Affected animals
rarely live beyond the age of 3 years and experience frequent bleeding
episodes from cyclic thrombocytopenia. Respiratory tract and enteric infec-
tions are the most debilitating.

Affected animals can often be housed together, but they need scrupu-
lously clean facilities to minimize infection, close clinical monitoring, and
supportive therapy. They should be monitored for neutropenia, and prophy-
lactic antibiotics should be administered as neutrophil counts begin to de-
cline.

Other hematologic disorders. Dogs with various other inherited and
acquired hematologic diseases also require special care. For example, basenjis
with pyruvate kinase deficiency and recurring anemia must be closely monitored
because of their increased susceptibility to infection or stress (Hall and
Giger, 1992; Harvey, 1989); beagles with hereditary nonspherocytic hemolytic
anemia must be closely monitored for episodes of hemolytic crisis (Maggio-
Price et al., 1988); and English springer spaniels with erythrocyte phospho-

SPECIAL CONSIDERATIONS 101

fructokinase deficiency require special care during episodes of hemoglobinuria
or myoglobinuria (Hall and Giger, 1992; Harvey, 1989).

Reproduction

For dogs with severe inherited bleeding disorders such as hemophilia,
von Willebrand's disease, factor X deficiency, and platelet dysfunction
(thrombopathia) special care is needed for breeding, whelping, and rear-
ing of the offspring. Immediately after birth, each pup should be carefully
examined for signs of bleeding, its umbilical cord should be ligated, and the
potential for trauma from the dam should be minimized. It might be neces-
sary to tranquilize first-time dams slightly to protect the young. When the
pups are weaned and start to become more active, blood samples should be
taken to determine which pups are affected. In hemophilia, the affected
pups from a carrier (heterozygous) dam will be males, unless the sire is a
hemophiliac (hemizygote), in which case both affected hemizygote males
and homozygote females can be produced. Generally, male pups should be
watched more closely, and the affected ones should be removed and housed
separately if the litter is too rambunctious. Cages should be relatively
small; a floor area of about 30 x 36 in (76 x 91 cm) is recommended for the
average hemophilic pup.

Affected pups should be watched carefully after vaccinations. Modi-
fied live-virus vaccines might induce a relative thrombocytopenia and plate-
let dysfunction during the period of viremia (i.e., 3-10 days after vaccina-
tion) (Dodds, 1992). The pups are at substantial risk for spontaneous or
traumatic bleeding at this time because the vaccine effect on platelet func-
tion superimposes another hemostatic burden. All vaccinations should be
given subcutaneously with a small-gauge needle, preferably 23 or 25 gauge,
in the loose skin folds of the neck. Intramuscular injections in affected
animals should be avoided.

Affected pups should be housed initially in cages and eventually in
small pens. At teething, affected puppies often bleed excessively from the
gums; this necessitates use of a topically applied sealant and, on occasion*
transfusion therapy.

Immunologic Diseases
Primary Immunodeficiency and Autoimmune Diseases

Clinical Features

Immunodeficiency is characterized by failure to manifest a normal im-
mune response when challenged by infectious agents or other substances

702 DOGS: LABORATORY ANIMAL MANAGEMENT

that are foreign to the body. The subnormal response can result from a
defect in the afferent, central, or efferent limb of the immune system (see
review in NRC, 1989). Immunodeficiency disorders can be primary (i.e.,
inherited) or secondary (i.e., acquired). Primary immune deficiency can
result from an inherited defect in immunocompetent cells or effector mechan-
isms (e.g., complement or phagocytes) or can be associated with autoim-
mune disease or a deficiency in growth factors necessary for the optimal
function of immunocompetent cells (WHO Scientific Group, 1986). Sec-
ondary immune deficiency can be caused by various environmental factors,
including x rays, viral agents, toxic chemicals, and dietary deficiencies.

Several primary immunodeficiency diseases have been described in dogs,
including selective IgA deficiency (Campbell, 1991; Felsburg et al., 1985;
Moroff et al., 1986), IgM deficiency (Mill and Campbell, 1992; Plechner,
1979), common variable immunodeficiency (A. Rivas, New York State Col-
lege of Veterinary Medicine, Cornell University, Ithaca, N.Y., unpublished),
and severe combined immunodeficiency disease (Jezyk et al., 1989; Patterson
et al., 1982). Dogs with particular autoimmune diseases also suffer from
immunodeficiency. A high incidence of septicemia has been observed in
dogs that were bred to develop systemic lupus erythematosus (SLE) (Quimby
et al., 1979). Autoimmune hemolytic anemia (AHA) (Bull et al., 1971;
Dodds, 1983; Klag et al., 1993), immune thrombocytopenic purpura (ITP)
(Dodds, 1983, 1992; Waye, 1960), SLE (Grindem and Johnson, 1983; Monier
et al., 1988; Quimby, 1981), rheumatoid arthritis (RA) (Bell et al., 1991;
Carter et al., 1989; Quimby et al., 1978), Sjogren's syndrome (Kaswan et
al., 1985; Quimby et al., 1979), autoimmune thyroiditis (Gosselin et al.,
1982; Quimby et al., 1979; Rajatanavin et al., 1989; Thacker et al., 1992),
and thyrogastric disease (Quimby et al., 1978) have been found in research
dogs. Primary immunodeficiencies in dogs have also been associated with
the absence of the third component of complement (Winkelstein et al., 1981);
deficits in neutrophil function, including cyclic hematopoiesis (see page
100) (Knoll, 1992; Lund et al., 1967) and granulocytopathy (Knoll, 1992;
Renshaw and Davis, 1979); dysregulation of interleukin-6 (DiBartola et al.,
1990; Rivas et al., 1992); and deficiency of growth hormone (Roth et al.,
1980). Clinical signs of these diseases are presented in Table 6.7.

All dogs with primary immunodeficiencies are predisposed to infection.
Dogs with disorders associated primarily with hypogammmaglobulinemia,
complement, or phagocytic function are predisposed to bacterial infection
(Blum et al., 1985; Lund et al., 1967; Moroff et al., 1986; Renshaw and
Davis, 1979). Those with disorders of cell-mediated immunity have in-
creased susceptibility to fungi and viruses (Jezyk et al., 1989).

SPECIAL CONSIDERATIONS

103

TABLE 6.7 Clinical Signs of Selected Primary Immunodeficiency and
Autoimmune Diseases in Dogs

Immunologic Disease

Clinical Signs

Common variable immunodeficiency

IgM deficiency
Selective IgA deficiency

Severe combined immunodeficiency

Autoimmune hemolytic anemia

Immune thrombocytopenic purpura
Systemic lupus erythematosus

Rheumatoid arthritis
Sjogren's syndrome

Autoimmune (lymphocytic) thyroiditis

Thyrogastric disease

Granulocytopathy
Dysregulation of interleukin-6

Deficiency of growth hormone

Increased susceptibility to infectious diseases;
clinical presentation after the age of 6 months

Increased susceptibility to bacterial diseases

Increased susceptibility of some dogs to
infectious diseases of mucosal surfaces, such as
those of gastrointestinal, respiratory, and
urogenital tracts

Extreme susceptibility to bacterial, viral, and
fungal infections; clinical presentation in first
few weeks of life; death before reaching
maturity

Pallor, slight jaundice, splenomegaly,
lymphadenopathy, weakness, and shortness of
breath; profound anemia and recurrent episodes
of hemolytic disease in approximately 50% of
affected dogs

Bruise easily, prolonged bleeding after trauma

Rash, hemolytic anemia, immunothrombo-
cytopenic purpura, polyarthritis, and proteinuria;
females affected more frequently than males

Swollen painful joints generally multiple small
articular joints

Keratoconjunctivitis sicca (dry eyes); corneal
ulcers associated with dry eyes; excessive dental
caries; inflamed gums; signs associated with
hypothyroidism, including tendency to obesity,
tendency to seek warm places, bilaterally
symmetrical hair loss, and changes in skin
thickness

Signs associated with hypothyroidism, including
tendency to obesity, tendency to seek warm
places, bilaterally symmetrical hair loss, and
changes in skin thickness

Signs associated with hypothyroidism, inappe-
tence, megaloblastic anemia, and atrophic
gastritis

Increased susceptibility to bacterial infections

Familial Mediterranean fever, characterized by
fever, synovitis, and renal failure

Small body stature; generalized increase in
susceptibility to infectious diseases

104 DOGS: LABORATORY ANIMAL MANAGEMENT

Husbandry and Veterinary Care

Immunodeficient dogs pose special management problems. Immune
diseases must be diagnosed, their prognosis determined, and their therapy
monitored. A number of tests have been developed for those purposes,
including tests that assay T- and B-cell function (Ladiges et al., 1988, 1989),
identify serologic markers of autoimmune diseases (Kaplan and Quimby,
1983; Quimby et al., 1980), identify circulating immune complexes in rheu-
matic and neoplastic diseases (Carter et al., 1989; Terman et al., 1979), and
assay phagocyte function (Smith and Lumsden, 1983).

The susceptibility of immunodeficient dogs to infectious diseases is
handled in various ways. All immunodeficient dogs can benefit from an
environment that minimizes contact with canine pathogens; however, for
some of these conditions (e.g., severe combined immunodeficiency), cesar-
ean derivation and maintenance in a gnotobiotic chamber are required to
ensure survival. Pups with humoral deficiencies born to normal dams profit
from receiving maternal antibodies in colostrum, and their dams should be
immunized before being bred to ensure that high concentrations of antibod-
ies will be present. Adult dogs with humoral deficiencies can be helped by
transfusions of normal or hyperimmune serum or plasma or by administra-
tion of purified gamma globulin. Some dogs that are genetically predis-
posed to autoimmune diseases can be spared clinical illness for years by
housing them in gnotobiotic chambers; however, if they are moved to a
conventional environment, they quickly develop autoimmune disease (Schwartz
et al., 1978).

Dogs with autoimmune diseases should be carefully monitored and ap-
propriately treated. Treatment might involve immunosuppressive therapy
(e.g., for SLE, AHA, ITP, and RA), transfusions of red cells and platelets
(for AHA and ITP), splenectomy (for AHA and ITP), renal dialysis (for
SLE), administration of thyroxine (for autoimmune thyroiditis), administra-
tion of thyroxine and vitamin B 12 (for thyrogastric disease), and administra-
tion of artificial tears (see the section on ophthalmologic disorders) and
special dental care (for Sjogren's syndrome). Some dogs with growth hor-
mone deficiency benefit from injections of thymosin (Roth et al., 1980).
Bone marrow transplantation and systemic antibiotics are effective in treat-
ing dogs with neutrophil defects. Dogs with thrombocytopenia (as in SLE,
ITP, or Evan's syndrome) are predisposed to bleeding and bruising and
should be housed and maintained as described in the section on hematologic
disorders. Preliminary studies suggest that oral levamisole therapy is effi-
cacious in treating one type of canine common variable immunodeficiency
that is associated with ulcerative colitis and a predisposition to adenocarcinoma
of the intestine (A. Rivas, New York State College of Veterinary Medicine,
Cornell University, Ithaca, N.Y., unpublished). Trials involving the use of
colchicine to delay the onset of amyloidosis in dogs with interleukin-6

SPECIAL CONSIDERATIONS JQ5

dysregulation are in progress (L. Tintle, Wurtsboro Veterinary Hospital,
Wurtsboro, N.Y., unpublished). The care of dogs with C3 deficiency and
dogs that have been exposed to total body irradiation and immunosuppres-
sive drugs associated with organ transplantation is described below. Dogs
should be immunized against known canine pathogens before being exposed
to agents that will induce immunodeficiency.

Reproduction

In colonies where the objective is to reproduce dogs with SLE by se-
lecting breeders with serologic evidence of the disorder (i.e., by using anti-
nuclear antibody and LE-cell tests), many progeny develop autoimmune
diseases not apparent in the parents (Monier et al., 1988; Quimby et al.,
1979). That observation has led to the hypothesis that multiple genes con-
trol the susceptibility and specificity of autoimmune diseases (Monier et al.,
1988; Quimby and Schwartz, 1978). In some cases, an unanticipated result
is compromised fertility (e.g., immune-mediated aspermatogenesis), which
necessitates the use of littermates or repeat breeding of the parents to con-
tinue the lineage (Quimby et al., 1978). Hypothyroidism caused by lym-
phocytic thyroiditis (Beierwaltes and Nishiyama, 1968; Gosselin et al., 1982;
Mizejewski et al., 1971; Rajatanavin et al., 1989; Thacker et al., 1992) can
lead to poor reproductive performance that can be corrected with thyroxine-
replacement therapy. Details on monitoring blood thyroxine and oral supple-
mentation have been published (DePaolo and Masoro, 1989; Ferguson, 1986).
For some autoimmune diseases, such as immune-mediated aspermatogenesis,
no therapy has been found.

Complement Deficiency

Clinical Features

Dogs deficient in the third component of complement (C3) are particu-
larly susceptible to bacterial infections (Blum et al., 1985). They also
develop a membranoproliferative glomerulonephritis, which can be detected
histologically by the age of 1 year (Cork et al., 1991). Affected dogs are
normally active and appear well; the only clinical sign of this renal disease
is proteinuria. Renal disease progresses inexorably and culminates in a
nephrotic syndrome with azotemia when the dogs are 6-8 years old.

Husbandry and Veterinary Care

Dogs deficient in C3 can be reared and housed in standard laboratory
dog facilities. Because the dogs are susceptible to bacterial infections (Chick
et al., 1984), animal technicians should be alert to any deviations from

106 DOGS: LABORATORY ANIMAL MANAGEMENT

normal behavior that might indicate illness (e.g., inappetence and lethargy).
CS-deficient dogs that show these clinical signs must immediately be evalu-
ated for increased body temperature and leukocytosis. Blood samples should
be taken and submitted for culturing to identify and determine the antibiotic
sensitivity of the microorganisms; however, treatment with intravenous bac-
tericidal antibiotics should not await diagnosis but should begin as soon as
clinical signs are detected and a blood sample has been drawn. Although
that protocol undoubtedly results in overtreating and might preclude a de-
finitive diagnosis, it will in most cases ensure the recovery and survival of
the affected dog. If an invasive procedure (e.g., renal biopsy or placement
of an indwelling catheter) is required, antibiotic prophylaxis should begin
24 hours beforehand, and it is essential to follow strict aseptic technique
while performing the procedure.

The presence of proteinuria can be detected by testing for total-protein
excretion in the urine over a 24-hour period, and renal biopsies can be used
to evaluate the progression of renal disease. As dogs age, periodic mea-
surements of total serum protein, albumin, and serum urea nitrogen can be
used to identify dogs whose renal disease is becoming severe or those in
which a nephrotic syndrome might lead to fluid accumulation in body cavi-
ties. Repeated blood transfusions or infusions of canine plasma are contraindi-
cated because they exacerbate renal disease.

Reproduction

C3 deficiency is inherited as an autosomal recessive trait (Johnson et
al., 1986; Winkelstein et al., 1982). Affected pups are produced by breed-
ing heterozygous females with homozygous males. Homozygous females
are fertile but have rarely produced viable young. Pups should be tested at
birth, and the ones that are C3-deficient should be placed on antibiotic
therapy for the first 4 days after birth. C3-deficient dogs do not respond
normally to immunization; therefore, it is recommended that immunizations
against the common canine pathogens be given at 2-week intervals until the
pups are 18 weeks old (Krakowka et al., 1987; O'Neil et al., 1988; Winkelstein
et al., 1986).

Organ Transplantation

Clinical Features

Dogs that are used in organ-transplantation studies must first be made
immunodeficient. Immunosuppressive methods include total-body irradia-
tion and administration of cytotoxic chemicals (Ladiges et al., 1989). Im-

SPECIAL CONSIDERATIONS 1 07

munosuppressed dogs are very susceptible to infectious diseases and might
have gastrointestinal tract problems.

Husbandry and Veterinary Care

Dogs that undergo experimental organ transplantation generally require
intensive postoperative supportive care, the level of which depends on the
transplantation procedure used and the degree of immunosuppression re-
quired to overcome graft rejection. Supportive care includes fluid therapy,
blood and platelet transfusions, preoperative and postoperative administra-
tion of appropriate antibiotics, and intensive husbandry practices. Regular
monitoring of white cells is critical for ascertaining health status and deter-
mining the necessity for treatment. Blood should be cultured if clinical
signs suggest septicemia. Nutritional needs are critical for dogs undergoing
bowel transplantation or for those suffering from gastrointestinal tract prob-
lems caused by the immunosuppressive procedures. Dogs might need to be
housed individually in intensive-care facilities during early convalescence.

Dogs undergoing bone marrow transplantation are profoundly immuno-
deficient for 200-300 days after lethal total-body irradiation and successful
marrow engraftment, and they require intensive supportive care (Ladiges et
al., 1990). Recovery of granulocyte count and function is complete by the
twenty-fifth day after engraftment; blood lymphocyte count does not return
to normal until day 200. Antibody response to bacteriophage and sheep and
chicken red cells is lower than normal during the first 200 days, with IgM
being the primary isotype. Lymphocyte stimulation by phytohemaggluti-
nin, the mixed-leukocyte reaction, and the response to first- and second-set
skin grafts are impaired. Long-term survivors (dogs that survive more than
200 days) generally regain their health and are no longer more susceptible
than normal to infectious diseases. The development of graft-versus-host
disease and its treatment drastically affect recovery of the immune system
and place the dogs at increased risk for contracting infections.

Lysosomal Storage Diseases

Clinical Features

Clinical manifestations of canine lysosomal storage diseases (LSDs)
generally fall into three categories: severe neurologic signs, mainly skeletal
signs, and a mixture of visceral, skeletal, and neurologic signs. The follow-
ing discussion addresses techniques for managing dogs in each category,
using a single LSD as an example. The techniques can be extended to
manage dogs with other LSDs.

108 DOGS: LABORATORY ANIMAL MANAGEMENT

Fucosidosis. Fucosidosis is caused by a deficiency of oc-L-fucosidase
(Healy et al., 1984). Affected dogs exhibit mainly neurologic signs. By the
age of 12 months, affected dogs show subtle behavioral changes and might
have an overextended posture. From 12 to 18 months, they develop mild
ataxia and hypermetria. Signs progress rapidly between the ages of 18 and
24 months to more severe deficits in gait, proprioceptive defects, hyperclonus,
nystagmus, kyphosis, and a loss of learned behavior. The dogs become dull
and unresponsive. Hearing and vision might be impaired. Signs in severely
affected, 24- to 36-month-old dogs include severe incoordination, opisthotonos,
muscle spasms, muscle wasting, circling, head tilt, abnormal pupillary light
reflexes, dysphagia, and cranial nerve deficits. The dogs become severely
obtunded and suffer from self-inflicted injury. If not euthanatized, they
usually die by the age of 3 years.

Mucopolysaccharidosis VII. The majority of clinical signs in canine
mucopolysaccharidosis VII (MPS VII), a condition caused by a deficiency
of (3-glucuronidase, are related to skeletal and joint abnormalities (Haskins
et al., 1984). Progressive noninflammatory arthrosis develops, and joints
become lax and deformed. By the age of 3-6 months, affected dogs are
unable to stand, and the muscles of locomotion atrophy. Corneal clouding
can lead to decreased vision in dogs with MPS VII, but the impairment is
generally less severe than in dogs with MPS I. At the age of 15-22 months,
MPS Vll-affected dogs often become dull and lethargic and lose interest in
their environment and in animal-care personnel. Those signs might be asso-
ciated with progressive hydrocephalus.

Mucopolysaccharidosis I. Canine mucopolysaccharidosis I (MPS I), a
condition caused by a deficiency of a-L-iduronidase, is most similar to the
human MPS I phenotype of intermediate severity (Hurler's syndrome and
Scheie's syndrome) (Shull et al., 1982). Clinical signs refer to visceral,
skeletal, and mild neurologic injury. Dogs with MPS I appear normal at
birth, although there is a higher than normal incidence of umbilical hernias.
Affected pups remain generally healthy for 4-6 months and then show stunted
growth, corneal clouding, and progressive, degenerative, noninflammatory
joint disease caused by mucopolysaccharide deposition in synovial and
periarticular tissues. Joint laxity caused by abnormalities in ligaments and
tendons is also common and, in combination with the arthroses, causes
decreased ambulation. Degeneration of intervertebral disks, collapse of
disk spaces, vertebral and long-bone osteopenia, and spondylosis also de-
velop. Mucopolysaccharide accumulation in heart valves and coronary ar-
teries can cause rapidly progressing heart failure. Affected dogs remain
alert and responsive until their death by natural causes or euthanasia, often
between the ages of 2 and 3 years.

SPECIAL CONSIDERATIONS 109

Husbandry and Veterinary Care

Dogs with LSD present unique and serious medical and husbandry problems.
Proper care of these valuable, critically ill animal models requires compas-
sion, diligence, hard work, and specialized knowledge of the diseases in-
volved. Technicians must be well trained and observant.

Fucosidosis. As the clinical signs progress, affected dogs should be
handled carefully to prevent injury. They should be fed, exercised, and
housed separately from normal dogs. Severely ill dogs should be moved by
carrying. Affected dogs should always be housed on a raised trampoline
bed and kept dry during cage cleaning to prevent self-soiling and pressure
sores. Particular attention should be given to dogs with long hair; they
should be bathed weekly and clipped several times a year. Ears should be
checked daily for signs of infection. Dogs with moderate to advanced
disease should be fed more frequently, and canned or moistened dry food
should be used to aid prehension. Dogs with advanced disease often have a
poor appetite, and the addition of highly palatable foods assists in maintain-
ing body weight. Excess dental tartar must be removed regularly. At the
age of 2-3 years, motor and mental impairment will have progressed to the
point that euthanasia will be indicated.

Mucopolysaccharidosis VII. MPS VH-affected dogs should be housed
in cages with floors of coated wire mesh; this aids sanitation and helps to
prevent decubital sores. Once the dogs are unable to walk, food and water
intake must be carefully managed. Recumbent animals will usually eat and
drink if pans of food and water are placed on the cage floor; however, hand
feeding might become necessary. Euthanasia should be considered when a
dog's response to human attention begins to diminish.

Mucopolysaccharidosis I. Except for surgical correction of umbilical
hernias, special care is not usually required for dogs with MPS I that are
less than 1 year old. However, as the disease progresses and the vertebral
column deteriorates, the dogs become extremely fragile, and especially gentle
handling is necessary when working with them or moving them between
cages. Acute disk herniation can occur with even very minor trauma or
inappropriate handling. Once skeletal disease has developed, exercise must
be limited, and affected dogs must be protected from more rambunctious
colony members. Decubital sores are a frequent consequence of the in-
crease in time spent lying down. Housing affected dogs on shredded news-
paper or elevated wire mesh provides both comfort and better sanitation.

Appetite generally remains normal, although hand feeding or varying
the diet might become necessary, especially in dogs with pronounced cor-

110 DOGS: LABORATORY ANIMAL MANAGEMENT

neal clouding, impaired hearing, or the rare decrease in cerebral sensorium.
Some dogs have enlarged tongues; however, prehension of food is generally
not a problem. The teeth of dogs that are fed a diet composed mainly of
canned food require periodic scaling of tartar.

MPS I-affected dogs are rarely maintained until they die naturally. By
the age of 24-36 months, the symptoms of skeletal disease are generally so
marked that euthanasia is indicated before debilitation becomes unaccept-
able.

Reproduction

Most LSDs can impair fertility in dogs. MPS I- and VH-affected males
have sired litters by artificial insemination. Males with fucosidosis show
copulatory behavior before they become severely uncoordinated, but they
are infertile because of epididymal lesions, which probably impair sperma-
tozoan capacitation. Females with fucosidosis are fertile but are very poor
mothers; their pups usually must be fostered or hand-reared. Pups with
LSDs are generally produced by breeding heterozygous carriers that are
clinically normal.

Muscular Dystrophy

Clinical Features

A genetic disorder homologous to Duchenne's muscular dystrophy of
humans a devastating, fatal disorder predominantly of boys occurs in
various breeds of dogs. The disorder in dogs, which is inherited as a simple
sex-linked recessive gene with full penetrance, is known as canine X-linked
muscular dystrophy, and dogs with the condition are called xmd dogs. The
mutation has been found in golden retrievers and rottweilers, and a similar
mutation is suspected to have occurred in samoyeds, malamutes, and Irish
terriers. The golden retriever is the best studied of the affected breeds, and
the following discussion is based on data on this breed.

Both Duchenne's muscular dystrophy and canine X-linked muscular
dystrophy are caused by a defect in the production of dystrophin, a skeletal
muscle cytoskeletal protein. The mutation in the dystrophin gene results in
massive continuing skeletal muscle degeneration that occurs from birth on-
ward. In dogs, progressive cardiac muscle degeneration begins in hemizy-
gous males at the age of about 6 months. Carrier bitches appear clinically
normal but have subtle lesions in their cardiac muscles. Because of the
homology to Duchenne's muscular dystrophy, the xmd dog can serve as an
animal model for studies leading to better understanding of the pathogen-

SPECIAL CONSIDERATIONS 111

esis of Duchenne's muscular dystrophy, as well as for studies designed to
assess therapeutic approaches (Valentine et al., 1992).

Clinical signs of obvious weakness, muscle wasting, and abnormal gait
appear in xmd dogs at the age of about 8 weeks. After that time, clinical
signs progress, and they are most severe at the age of about 6 months, at
which time the dogs have a markedly stiff, shuffling gait. There is fre-
quently a severely abnormal posture, with carpal overextension, tarsal over-
flexion, and splaying of the limbs. The dogs are unable to open their jaws
fully, their tongues are thickened and cannot be fully extended, and they
frequently drool excessively. After the age of 6 months, the clinical disease
appears to stabilize, and many dogs seem to gain strength as they age.
However, there is still a progressive degeneration and fibrosis of cardiac
muscle that results in the characteristic Duchenne-type cardiomyopathy.

Husbandry and Veterinary Care

Dystrophic dogs do not require special caging. Shavings provide a soft,
warm surface, but the shavings must be free of dust so that the dogs do not
inhale particles and develop granulomatous pneumonia. Temperature and
humidity must be carefully controlled. Older dystrophic dogs should be
monitored carefully for signs of cardiac failure. Treatment for heart failure
has been described (Fraser et al., 1991). Euthanasia should be considered
when treatment fails to alleviate clinical signs (e.g., when the dog has diffi-
culty breathing and when fluid accumulates in the abdomen).

Dystrophic dogs require high-calorie food that is easy to prehend and
swallow because of the weakness of their tongue, jaw, and esophageal muscles.
Canned food mixed with moistened dry food seems to constitute an ad-
equate diet, but careful monitoring of food intake and weight is necessary.
Regurgitation of food is common because of the esophageal skeletal muscle
dysfunction. Severely disabled dogs might not be able to use automatic
watering devices and might have to be given water in bowls or buckets.
Their water might need frequent changing because of a buildup of saliva.

Adequate exercise is crucial during the period of rapid growth. Al-
though dystrophic dogs might prefer to lie down, restricted exercise will
result in more severe joint contractures. The presence of a slightly more
active dystrophic cagemate is ideal, provided that competition for food does
not impair food intake. The kennel must have a nonslippery surface to
provide traction, and daily release for exercise is advised. These dogs
should not be forced to exercise, however, because it might lead to in-
creased muscle damage.

Dystrophic dogs cannot groom themselves adequately. Regular brush-
ing of their haircoat and clipping of overgrown toenails is required. To

112 DOGS: LABORATORY ANIMAL MANAGEMENT

prevent skin irritation, the mouth and jaw should be kept free of the saliva
and food that accumulate.

Reproduction

Many dystrophic dogs survive to breeding age, and breeding colonies
can be established. Some affected males are able to breed naturally; others
are hampered by their physical disability and require artificial insemination
techniques. An xmd male that breeds naturally might need assistance to
remain upright once he has "tied" with the female. Breeding dystrophic
bitches, which are produced by mating dystrophic males to carrier bitches,
is possible but not advised. Pregnant dystrophic bitches require constant
monitoring, are likely to have respiratory and cardiac complications, will
require cesarean section, and might not be able to care for their pups ade-
quately.

At whelping, a safe, warm environment and proper maternal care are
essential for the survival of dystrophic pups. If dystrophic pups are stressed
by cold, separation from the litter, or inability to compete with normal pups
in a large litter, some of them will develop massive skeletal necrosis within
the first few days of life. Once signs of severe weakness have developed in
a pup, it is virtually impossible to save it. Severe diaphragmatic necrosis
resulting in respiratory failure appears to be the cause of death. Dystrophic
pups can be identified in the first week of life by their markedly increased
serum concentrations of creatine kinase released from degenerating muscles.
Dystrophic pups that survive the first week grow more slowly than their
littermates. Euthanasia should be considered for pups that are too weak to
nurse during the first week of life; tube feeding has not been successful in
keeping such pups alive (B. A. Valentine, Department of Pathology, New
York State College of Veterinary Medicine, Cornell University, Ithaca, N.Y.,
unpublished).

Neurologic Disorders

Clinical Features

Dogs with hereditary or induced neurologic disorders are often used to
study equivalent human disorders. Clinical signs in these dogs include
abnormal gait, hyperactivity, nervousness, tremors, convulsions, visual im-
pairment, blindness, deafness, quadriplegia, and tetraplegia. Obviously,
these dogs commonly require extra care to ensure that they are as comfort-
able as possible. Inherited canine neurologic diseases and their clinical
signs have been reviewed by Cummings (1979) and Oliver and Lorenz

SPECIAL CONSIDERATIONS 113

(1993); the pattern of inheritance of specific diseases has been discussed by
Willis (1989).

Husbandry and Veterinary Care

Food and water must be placed where a neurologically impaired dog
can find and reach them easily, and, if the dog is blind, placement should be
consistent. That might require using water bowls instead of automatic wa-
terers or, for dogs with severe impairment, intravenous or subcutaneous
administration of fluids. Food might have to be placed in flat dishes, soft-
ened, or made into a gruel so that it can more easily be reached, masticated,
and swallowed. Food and water intake should be monitored. Dogs should
be weighed regularly to ensure that body weight is maintained. Nasogastric,
lavage, pharyngotomy, or intragastric feeding might be required in some
circumstances to provide adequate nutrition.

Dogs with sensory deficits can experience dysesthesias and might re-
spond by chewing the affected limb or body part or another, more acces-
sible body part. Several strategies can be used to deal with such behavior.
Dogs should be closely monitored to detect the beginning of self-directed
behaviors. A dog can sometimes be distracted by housing it where it has
more external visual and social stimulation. If a nonaggressive cagemate
can be identified, social housing might be sufficiently distracting provided
that the cagemate does not harass the affected dog or prevent it from eating
and drinking. Toys, such as rawhide bones, might also be useful. If ban-
dages must be used, they should not be too tight and should be checked
regularly. Elizabethan collars or muzzles can be used to limit access to the
body. Light tranquilization, if it does not interfere with the experimental
protocol, might be helpful.

Dogs with sensory deficits might require extra or different bedding to
prevent unintentional self-injury. The dogs' primary housing must be free
of rough or sharp edges and projections. Dogs with motor deficits might
have difficulty in positioning their bodies for urination and defecation. Some-
times all that is necessary is to provide flooring with better traction (e.g.,
plastic-coated grids or rubber mats). If necessary, research or animal-care
personnel should assist the dog to position itself. Catheterization or manu-
ally expressing the bladder might be required to prevent urinary retention.
Careful husbandry and nursing will avoid decubitus ulcers.

In dogs with respiratory deficits, the normal ability to thermoregulate
by panting has been compromised. For these animals, exertion must be
avoided and comfortable temperatures maintained.

114 DOGS: LABORATORY ANIMAL MANAGEMENT

Reproduction

Dogs with some neurologic disorders can reproduce, even though they
are severely impaired. Such dogs usually need assistance for mating or
require artificial insemination. Bitches with marked sensory or motor defi-
cits or ataxia should be closely attended at parturition and while nursing to
protect the pups from accidental injury. If the neurologic deficits of the
dam interfere with her ability to care for her offspring, hand rearing or
foster rearing will be required.

Ophthalmologic Disorders

Clinical Features

Dogs are affected by various Ophthalmologic problems, either as inher-
ent aspects of the research in which they are being used, as complications,
or as acquired conditions unrelated to the research. Descriptions of canine
eye diseases can be found in any standard text on veterinary ophthalmology
(e.g., Gelatt, 1991; Helper, 1989). In the research setting, ocular problems
that require special management techniques are visual impairment, painful
ocular conditions, untoward sequelae of interfering with the eye's external
protective mechanisms, and combinations of these conditions.

Blindness. Visual impairment in dogs usually cannot be measured pre-
cisely. For purposes of this discussion, blindness is used, in a loosely
defined manner, to refer to any condition in which visual impairment is
sufficient to interfere with a dog's ability to perform visually guided tasks
or to exhibit normal visually guided behavior. In general, dogs maintained
in a familiar environment adapt well to visual deficits that are congenital,
are gradual in onset, or have been present for an extended time (weeks to
months). A dog that has adapted to its blindness, that is maintained in a
familiar environment, and that is not subjected to stressful experiences will
move about actively and engage in all normal canine behavior. Its adapta-
tion, or compensation, might be so successful that a naive observer will not
recognize that it is blind.

Ocular pain. Painful ocular conditions fit broadly into three categories.
External ocular pain is usually associated with corneal irritation and com-
monly causes obvious signs, such as blinking, excessive tearing, and red-
ness. Uveal pain is caused by intraocular inflammation, which might not be
evident without careful examination of the eye; uveal pain is usually more
painful than corneal irritation. Glaucomatous pain is often the most insidi-
ous and most severe ocular pain. All these conditions are not only painful,
but can threaten a dog's vision and the integrity of the affected eye.

SPECIAL CONSIDERATIONS

Conditions associated with failure of the eye's external protective mecha-
nisms. Untoward sequelae can arise from any condition that interferes with
the eye's external defense mechanisms. These mechanisms depend on such
funcitons as corneal sensitivity, lid movement, and tear production. Any-
thing that reduces corneal sensation, interferes with lid movement, or low-
ers tear production can lead rapidly to painful ocular inflammation, impair-
ment of vision, and loss of the affected eye. Common causes include anesthesia,
radiation, surgical procedures, and drugs.

Husbandry and Veterinary Care

It is recommended that all experimental protocols involving dogs with
ophthalmologic problems whether the problems are "natural" (i.e., genetic),
acquired, or induced be reviewed by a veterinarian or a physician with
training in ophthalmology (e.g., a veterinarian certified by the American
College of Veterinary Ophthalmologists). Such protocols should include an
adequate program for monitoring the dogs' ophthalmologic problems and
written procedures for dealing with ocular emergencies.

Blindness. In spite of the ease with which dogs can adapt to blindness,
they require special protection from a variety of environmental dangers, the
more obvious of which are protruding objects, sharp edges, openings through
which a dog might fall, and sources of electric or thermal injury. More
insidious risks can arise because blind dogs lack the menace reflex, which
normally protects the cornea from damage by causing the eyelids to blink in
response to seen objects approaching the eye. Personnel responsible for the
care and handling of blind dogs must be aware of these risks and keep them
to a minimum and must watch for signs of acute or chronic corneal injury.

Dogs that have adapted to their blindness can become decompensated
in response to rapid changes in their environment or other stressful experi-
ences, such as anesthesia (e.g., for diagnostic, surgical, or experimental
procedures), illness, and alterations in their daily routine. A decompensated
chronically blind dog might look as though it has suddenly become blind
and might exhibit behaviors compatible with a general stress reaction
from stiff-limbed hesitancy in walking and an apparent fear of its surround-
ings to anorexia or polydipsia, polyphagia, and polyuria. Similar signs can
be observed in some dogs that have recently and rapidly lost their sight.
Given time and a restricted, safe, and consistent environment, the blind dog
will readapt and once again exhibit compensated normal behavior. Person-
nel responsible for the care and handling of blind dogs must be aware that
these dogs need consistent familiar surroundings and that they might react
adversely to stressful experiences. When approaching a blind dog, animal
technicians should talk to it so that the dog will be more likely to perceive
the approach as friendly.

116 DOGS: LABORATORY ANIMAL MANAGEMENT

Ocular pain. Ocular pain can vary from moderate to excruciating.
Dogs in ophthalmologic research colonies are often at risk of developing
ocular pain, either as a direct result of a study or as an unpredictable occa-
sional side effect. In some cases, particularly if the pain is chronic or
develops gradually, it will not be readily apparent without special examina-
tion procedures, especially if the observer is inexperienced. Personnel re-
sponsible for the care and handling of dogs used in ophthalmologic research
should suspect that ocular pain is present when there is periocular soiling or
when there are behavioral changes, such as decreased activity, decreased
appetite, increased yawning, and changes in vocalization patterns.

Conditions associated with failure of the eye's external protective mecha-
nisms. All protocols should be reviewed for potential adverse effects on
external ocular defense mechanisms, and dogs subject to such risks should
be monitored carefully for evidence of adverse effects.

Reproduction

Most dogs with ophthalmologic disorders can breed normally.

Orthopedic Disorders

Clinical Features

Dogs serve as models for both canine and human orthopedic diseases.
Spontaneous bone and joint diseases of dogs have been reviewed (Lipowitz
et al., 1993; Newton and Nunamaker, 1985; Whittick, 1990; Young, 1979).
Orthopedic diseases can also be induced in dogs.

Husbandry and Veterinary Care

When inducing an orthopedic disease in dogs, one must first evaluate
the dogs to be certain that natural bone and joint diseases are absent. Radi-
ography is used to diagnose hip dysplasia, osteochondrosis, osteoarthritis,
elbow dysplasia, and patellar luxation. These are considered heritable dis-
orders because offspring of affected parents often have them and they occur
in siblings.

Ideally, the surgical suite, the radiographic diagnostic facility, and an
anesthesia recovery box lined with foam-rubber padding should be located
near the primary housing facility. The floors of both the orthopedic re-
search facility and the primary housing should be kept dry and have a
nonslippery surface to provide good, steady footing.

SPECIAL CONSIDERATIONS 117

The amount of food consumed should be monitored because excess
body weight will exacerbate orthopedic conditions. Limiting food con-
sumption during the growth period has been shown to reduce signs of ortho-
pedic disease in dogs that mature at greater than 30 Ib (Kealy et al., 1992).
Dogs that refuse to eat because of pain might require a palatable high-
energy food to maintain body weight. Human socialization is desirable to
allow caregivers to detect abnormalities more readily and to facilitate han-
dling and, when necessary, treatment.

Mild exercise, such as walking, is beneficial to keep muscles limber,
promote bone formation, and increase lubrication and nutrition of joints.
However, excessive exercise aggravates pain and causes further bone or
joint damage. Anti-inflammatory drugs, given with food, can be used to
relieve pain. Glucocorticosteroids, although potent anti-inflammatory agents
that relieve pain, can also accelerate disease progression and should be used
only in advanced cases of joint disease. Warm packs can ease the pain of
chronic osteoarthritis. Dogs affected with skeletal diseases should be kept
warm and dry, although pain associated with a recent injury can be eased by
applying crushed ice in a plastic bag to the affected region.

Reproduction

Dogs with joint and bone diseases can generally be bred, although it
might be necessary to guide and hold a male affected with moderate or
severe hip dysplasia. If the orthopedic problem is so severe that mating is
not possible, artificial insemination can be used.

Radiation Injury

Clinical Features

Radiation is commonly used in experimental protocols involving dogs.
Total-body irradiation (TBI) is generally delivered by a cobalt-60 source or
medical x-ray therapy machine. Doses of radiation up to 2 Gy can result in
signs of illness related to mild gastrointestinal toxicity and decreased white-
cell counts. At doses of 2-4 Gy, signs become progressively more severe.
Doses greater than 4 Gy cause destruction of bone marrow, loss of circulat-
ing blood cells, immunosuppression, increased tendency to bleed, and mod-
erate to severe gastrointestinal toxicity. Bone-marrow transplantation can
prevent severe clinical signs and death in dogs. The high radiation doses
are similar to the doses that human transplantation patients receive.

Several side effects occur in dogs that survive for long periods after
TBI and bone-marrow rescue (Ladiges et al., 1989): pancreatic fibrosis,

118 DOGS: LABORATORY ANIMAL MANAGEMENT

malabsorption and malnutrition, radiation-induced cataracts, and malignan-
cies. A consistent finding is graying of the hair.

Radionuclides that are ingested, inhaled, or injected rarely produce signs
of illness. However, knowledge of the chemical form and metabolism of
the radionuclide is necessary to determine possible side effects. For ex-
ample, inhaled particles of oxides of cesium- 144 are relatively insoluble in
the lungs and potentially remain there for some time. Signs of radiation
pneumonitis might then be expected (Mauderly et al., 1980). Conversely,
strontium-90 as a chloride is relatively soluble in the lungs. When inhaled,
it is translocated to the bones, where it can cause prolonged thrombocytopenia
and neutropenia (Gillett et al., 1987).

Types of radiation. Radiation emissions can be alpha particles, beta
particles, gamma rays, and x rays. The distinctions between those emis-
sions are important for providing care for laboratory animals.

Alpha emissions from radionuclides, such as plutonium or americium,
are generally high-energy emissions, but they travel very short distances in
tissue. These radionuclides are rarely used in animals unless the study is
specifically intended to assess metabolic or biologic effects of alpha emis-
sions. No special precautions are needed for direct contact with animals
contaminated with alpha-particle-emitting radionuclides because the radia-
tion energy is absorbed within the animals' tissues. However, personnel
should wear disposable clothing, shoe covers, gloves, eye protection, and
respiratory protection to prevent inadvertent ingestion of, inhalation of, or
wound contamination with alpha particles from contaminated feces, urine,
bedding, cleaning water, or surfaces.

Beta-emitting radionuclides, such as cesium- 144 and strontium-90, pen-
etrate farther into animal tissues than alpha particles but still only a short
distance. The same precautions should be taken as are taken for alpha
particles. Dogs can usually be handled without taking further precautions
10-12 days after administration of radionuclides.

Gamma rays and x rays from internally deposited radionuclides pen-
etrate tissues for considerable distances. These emissions can cause some
radiation exposure of personnel, and it is important to know the potential
exposure levels. These are generally low-energy kinds of radiation with
short half-lives. Procedures for monitoring radiation must be in place to be
certain that exposures of personnel are within accepted standards. The
facility radiation-protection officer should participate in planning of ani-
mal-care procedures.

Disposal of radioactive wastes is regulated by both federal and state
governments. It is important to have procedures in place for collecting,
packaging, and labeling radioactive wastes before studies are initiated.

SPECIAL CONSIDERATIONS 119

Biohazards associated with radioactivity. Dogs exposed to external
radiation sources do not pose a hazard to personnel once exposure is com-
plete; the concern is for the effects on the health of the exposed animals.
However, dogs that are administered radionuclides by ingestion, injection,
or inhalation might present a continuing hazard to personnel because the
radionuclide will be excreted in feces, in urine, and in some instances in
exhaled air for some period after exposure. Standard operating procedures
must be developed and followed for collecting and disposing of all contami-
nated materials to protect animals and personnel. Animal health is of im-
mediate concern only when large quantities of radionuclides are given.

Husbandry and Veterinary Care

Dogs exposed to external radiation can be housed in the usual manner
(see Chapter 3); however, it is critical that immunosuppressed dogs be pro-
tected from other dogs that might harbor pathogens. Dogs given internally
deposited radionuclides should be housed individually. To facilitate collec-
tion of contaminated excreta and cage-cleaning water, the cages should be
designed for collection of urine and feces and should be easy to clean. Dog
rooms must have adequate ventilation, and ventilated air should not be
recirculated. It might also be necessary to filter exhaust air. To prevent
cross-contamination and simplify monitoring, it is recommended that dogs
exposed to the same radionuclide be housed in the same room.

Clinical observations and frequent peripheral-blood-cell counts are use-
ful for monitoring dogs exposed to large doses of radiation. Treatment for
reduced numbers of blood cells is supportive, and euthanasia should be
considered if illness becomes too severe. Marrow "rescue" can prevent
severe illness. Supportive care should consist of aggressive antibiotic and
fluid therapy, and a semiliquid diet is necessary during the immediate post-
irradiation period. Euthanasia should be considered in long-term survivors
experiencing pancreatic fibrosis, malignancies, or pneumonitis.

Reproduction

Dogs that have received TBI are usually sterile. Lower doses of radia-
tion have variable effects on reproduction.

Gene Therapy

Gene therapy can be used to correct inborn errors of metabolism,
hemoglobinopathies, and blood factor A deficiencies; to insert genes into
normal cells of the host (e.g., marrow stem cells) to increase their resistance
to the toxic effects of chemotherapy; to introduce genes into cancer cells

120 DOGS: LABORATORY ANIMAL MANAGEMENT

that will restore suppressor-gene function or neutralize the function of acti-
vated oncogenes; and to induce tolerance to transplantation antigens by
transferring genes that code for such antigens (Anderson, 1984). The use of
the dog as a preclinical, large, random-bred animal model has set the stage
for clinical gene therapy. A number of target tissues for gene therapy have
been used; this section will cover three of them.

Hematopoietic Stem Cells

In preparation for gene transfer, marrow is aspirated while the dog is
under general anesthesia. The hair over the shoulder and hip joints is
clipped. The skin is cleaned with povidone iodine, washed with 70 percent
ethyl alcohol, and cleansed with sterile Ringer's solution. Under sterile
conditions, a needle 20 cm long and 2.5 mm in internal diameter is inserted
into the marrow cavity through the proximal intertubercular groove of the
humerus or trochanteric fossa of the femur. The needle is then connected
with polyvinyl tubing to a suction flask, and marrow is aspirated by placing
a suction flask, which contains tissue-culture medium and preservative-free
heparin, under negative pressure with a pump. The procedure can be com-
pleted on all four limbs in approximately 20 minutes, during which 70-80
rnl of a mixture of blood and bone marrow is collected. The marrow sus-
pension is then passed through stainless-steel screens with 0.307- and 0.201-
rnrn mesh diameters. A 1 ml sample is taken for marrow cell counts, and
the remainder of the marrow is placed in plastic containers. The aspiration
procedure is well tolerated without any sequelae. Dogs are capable of
walking unimpaired after recovery from anesthesia.

Nucleated marrow cells are then cocultivated with virus-producing packaging
cells at a ratio of 2:1 for 24 hours in 850-ml roller bottles. The gene-
containing vector is replication-defective. Retrovirus-producing packaging
cells are seeded in roller bottles 48 hours before the addition of marrow and
are cultured in vitro with established techniques. After cocultivation, mar-
row cells are used to boost long-term cultures established 1 week earlier.
The cultures are harvested after 6 days of incubation, and marrow cells are
carefully removed without dislodging the virus-producing packaging cells,
washed, resuspended in serum-free medium, and infused intravenously into
the dog from which the marrow was taken.

In preparation for the infusion, the dog is exposed to total-body irradia-
tion to create room for the infused marrow to seed. Total-body irradiation
is administered at doses of 4-10 Gy and is usually delivered at a rate of 7
cGy/minute from two opposing cobalt-60 sources. For that purpose, an
unanesthetized dog is housed in a polyurethane cage that is midway be-
tween the two cobalt-60 sources. The long axis of the cage is perpendicular
to a line between the sources. After irradiation, the dog is returned to the

SPECIAL CONSIDERATIONS 121

animal-care facility for supportive care. Total-body irradiation can cause
nausea, vomiting, and diarrhea. Its destruction of normal marrow leads to a
disappearance of red cells, white cells, and platelets. The temporary ab-
sence of those blood components produces a risk of anemia, infection, and
bleeding that persists unless the dog receives a marrow graft and the graft
begins to function. Dogs are monitored daily and receive parenteral fluids
and electrolytes as required. Appropriate preoperative and postoperative
antibiotics are routinely used to prevent and treat infections. Platelet and
red-cell transfusions are given as needed. Marrow-graft function is moni-
tored by evaluating daily blood counts.

The success of gene transfer can be assessed by repeated aspiration of
marrow under general anesthesia and examination of the samples for the
appropriate marker gene with culture techniques, the polymerase chain re-
action, or other appropriate methods (Stead et al., 1988). Peripheral blood
cells can be tested in a similar manner, as can lymph node lymphocytes and
pulmonary macrophages (Stead et al., 1988).

Skin Keratinocytes

Skin keratinocytes provide another good target for gene insertion. For
some gene products, such as adenosine deaminase, gene transfer can take
place in any replicating tissue. A 2 x 1.5-cm skin biopsy is obtained from
the recipient under general anesthesia. Keratinocytes are derived from the
biopsy material and cocultivated in vitro with replication-deficient retroviral
vectors that contain the gene of interest. Keratinocytes are then cultured in
a liquid-air interface culture, which gives rise to the various layers of skin
in an in vitro system. After some time in culture, the skin grown in vitro is
transplanted into a prepared bed on the flank of the dog under general
anesthesia. The transplant site is treated with topical antibiotic powder,
protected by nonadhering dressing, and inspected daily by the investigators.
Generally, the skin grows in and is functional in 3-4 weeks. Punch biopsies
of 2-3 mm allow assessment of gene transfer (Flowers et al., 1990).

Smooth Muscle Transplantation

Because of their location, genetically modified vascular smooth muscle
cells can be particularly useful for the treatment of some diseases (e.g.,
hemophilia). Studies have demonstrated that vascular smooth muscle cells
are easily obtained, cultured, and genetically modified and replaced and
provide a good target tissue for gene therapy that involves both secreted and
nonsecreted proteins (Lim et al., 1991). A segment of femoral artery or
vein is surgically removed from a dog for preparation of smooth muscle cell
cultures. The procedure of removing femoral artery and vein segments will

722 DOGS: LABORATORY ANIMAL MANAGEMENT

not compromise the dog, because there is extensive collateral circulation in
this region. With the dog under general anesthesia, as long a segment of
vessel as possible (at least 2 cm) is isolated from the circulation with liga-
tures. Any side branches in the two ends are permanently ligated before the
vessel is removed. The smooth muscle cells are isolated, cultured, and
infected with replication-defective amphotropic retroviruses that carry the
genes of interest, in accordance with National Institutes of Health recombi-
nant-DNA guidelines. The genetically modified smooth muscle cells are
returned to the animal from which they were obtained. With the dog once
again under general anesthesia, the transduced cells are seeded into the left
and right carotid arteries and into the remaining femoral arteries (Lim et al.,
1991).

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SPECIAL CONSIDERATIONS

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SPECIAL CONSIDERATIONS 129

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Appendix

Cross Reference

Subject

Page No.
in This
Report

Part No.
in AWRs
(9 CFR)

Page No.
in Guide

Bedding storage

3.1e

Chemicals and toxic substances

22,25

Emergency power

Exercise

21-24

3.8

Feeding

25-26

3.9

22-23

Food storage

3.1e

23,46

Handling

2.131

Housing facilities

General construction

12-14

3.1a-b, 3.4c

42-43

Drains

14-15

3. If

Lockers, washrooms, and toilet areas

13, 15

3.1g

6,42

Physical relationship of animal

facilities to laboratories

Power and Lighting

3. Id

Surfaces

14-15

3.1c ,3.2d

43-45

Humidity, indoor

16-17

3.2b

18-19,45

Identification

27-28

2.38g, 2.50

Illumination

3.2c

20-21

Noise

132

APPENDIX

Subject

Page No.
in This
Report

Part No.
in AWRs
(9 CFR)

Page No.
in Guide

Outside runs

15-16

3.3e

Primary enclosures

19-20

3.6a,c,d

11-12

Procurement

52-53

2.60

Protocol review

76-78

2.31c,d

Record-keeping

Annual or semiannual reports

2.36

Dogs on hand

28-29

2.35b-e

Dog procurement

28-29

2.35b

Institutional animal care and

use committee

2.35a

Restraint

Sanitation

3.11

24-27

Social interaction

22-24

3.6c3, 3.7

12-13

Space

20-21

3.6a,c

13-17

Temperature, indoor

16-17

3.2a

18-19,45

Training employees

2.32, 3.12

4-5

Transportation

29-32

3.13-3.19

Ventilation, indoor

17-18

3.2b

19-20,

45-46

Veterinary care

Analgesia

66-67

2.33b

Anesthesia

64-66

2.33b

Conditioning

34-35

Emergency, weekend, and

holiday care

2.33b

Euthanasia

70-72

2.33b

38-39

General

2.33, 2.4

Postsurgical care

69-70

2.33b

37-38

Quarantine

54-55

34-35

Surgery

68-69

2.31d

9-10, 37-

38, 47-48

Surveillance, diagnosis, treatment,

and control of infectious diseases

53-57

2.33b

36-37

Waste disposal

3.1f

26-27

Watering

3.10

Index

Acromegaly, 94, 96

Addison's disease (hyperadrenocorticism),

93, 95-96
Adenovirus, 54-57
Adipose tissue, 26
Aging, 79-81
Alaria canis, 62
Albumin, 106
Alpha-2 agonists, 67
Amebas, 58, 59

American College of Veterinary
Ophthalmologists, 115

American Veterinary Medical Association
(AVMA) Panel on Euthanasia, 70-71
Ameroid, 88-89
Analgesics

anti-inflammatory nonsteroidal, 67

euthanasia, 70-71

opioid, 66-67

pain alleviation, 63-68

postsurgical, 68-69
Ancylostoma spp., 44, 59-61
Anemia, 100
Anesthesia and anesthetics

alleviation of pain, 64-68

euthanasia, 70-71

gene therapy, 120, 122

general, 64-66, 69

inhalants, 64, 71

injectable drugs, 64-65, 70-71

local, 66

hypothermia, 17

neuromuscular blocking agents, 65-66

presurgical, 69

Anestrus, 41, 81

Angiotensin-converting enzyme (ACE), 87-

88,91

Animal Welfare Act, 1, 11
Animal Welfare Regulations (AWRs)
cross referenced, 131-132
defined, 1-2
Antigens, 5, 120
Antibiotics, 69
Arthritis, 5, 79

Artificial insemination, 37-39
Ascarids (Toxocara canis; Toxascaris

leonina\ 58-60
Association of American Feed Control

Officials, 24, 42
Attachment formation, 44-45
Auscultation, 85
Autoimmune diseases, see Immunologic

diseases; and specific diseases
Autoimmune hemolytic anemia, 102-104
Autoimmune (lymphocytic) thyroiditis, 102-

104

Babesia spp., 62-63

Babesiosis, 62-63

Bacterial diseases, see specific diseases

Balantidium spp., 58-59

Barbiturates, 70

Bedding and resting apparatus, 11, 26-27,
30, 113

Behavior

aging, 79

aggressive, 5, 23, 30, 45-46, 67, 70

blindness and ocular pain, 115-116

755

134

INDEX

fearful, 23, 45-46, 53, 67-68

herding, 5

maladaptive, 22, 53, 67

neurologic disorders, 108-109

record-keeping, 46

selection of experimental animals, 7-9

socialization, 7-9, 11, 22-24, 44-46, 53

see also Stressors and distress
Benzodiazepines, 67-68
Biohazards, 119
Bioimplants, 85
Bladder disorders, 81
Bleeding disorders, 99-101
Blindness, 114-115
Blood glucose monitoring, 94
Blood pressure, 89-90
Blood urea nitrogen (BUN), 89
Body size, 7, 25-26, 30
Body weight, 7, 25-26, 30, 39-40, 42-43, 67,

80,95,99, 117
Bone marrow transplantation, 107, 117, 120-

121

Bordetella bronchiseptica, 54-56
Breeding colonies

deworming, 43-44

infectious diseases, 40-41, 55-56

neonatal care, 39-47, 56

nutritional requirements, 42-43

record-keeping, 46-47

reproduction, 35-41, 83-84

socialization, 44-46

specific-pathogen-free, 57

vaccination, 43-44, 55-56

see also Specific-pathogen-free
animals; Reproduction; Vaccines
and vaccination
Bruce I la canis, 37, 55
Brucellosis, 37, 55

Cages and pens, 19-20, 30-31

Calcium derangements, 93-97

Carbon dioxide, 71

Carbon monoxide, 7 1

Cardiovascular diseases, 5, 61, 70, 80-87;

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Full text of "Laboratory Animal Management Dogs"

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