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UNITED STATES DEPARTMENT OF AGRICULTURE

; BULLETIN No. 260

Contribution from the Bureau of Animal Industry
A. D. MELVIN, Chief

Washington, D. C. Vv November 23, 1915

THE DOG AS A CARRIER OF PARASITES AND
DISEASE.

By Mavrice C. Hatt, Ph. D.,
« Assistant Zoologist, Zoological Division.

CONTENTS.
Page. Page.
Diseases and parasites carried by the Diseases and parasites carried by the
dog. 2 dog—Continued.
Rabies 3 Tapeworms, roundworms, etc__-_ 15
Hydatid_ 2 5 Fleas and ticks _-__-___--_--_ 19
Gld- 22a ces 9 Miscellaneous parasites ____--~ 22
Cysticerecus (measles) in sheep Conclusion _ 24
and other animals________-_ 11

In the evolution of civilization the dog was one of the most useful
animals ever domesticated by man. In addition to his usefulness,
other admirable qualities have endowed him with a certain senti-
mental esteem as a pet. The part the dog plays as a carrier of dis-
ease, however, has only recently been recognized, and his status has
not yet been changed to satisfy modern hygienic precautions or even
to meet altered conditions of life in cities.

Whether in the city or in the country, the dog is commonly allowed
a degree of freedom which is approached only by that of the less
social and consequently less dangerous cat. Liberties which we do
not allow our horses, cattle, children, or selves are extended by many
persons to their dogs. They are permitted to run unquestioned over
lawns or farms, to plant bones in flower beds, to litter up porches and
walks with trash and filth, to lick the faces of children, to wipe their
muddy paws on strangers’ clothing, to go unmuzzled when rabies
with its terrible agony and attendant death is abroad, and to roam
afield at nights and run sheep to death.

* Norn.—tThis bulletin points out the increasing damage done by the stray and uncared-
for dog as a carrier of parasites and disease germs harmful to both man and live stock,
and is especially intended for the use of physicians, veterinarians, and health officers.

94288°—Bull. 260—15. 1

2 BULLETIN 260, U. S, DEPARTMENT OF AGRICULTURE,

As has been said, the dog himself has many delightful and useful
qualities. It is our thoughtless tolerance of his present unwar-
ranted liberty and license that permits this survivor of the days
when the dog was man’s faithful and valuable ally against the rest of
the animal world to become a pest and a danger. There is a growing
conviction that while his innate qualities and the fund of affectionate
sentiment which attaches to him warrant the preservation of the dog
with a responsible owner who will keep him clean and free from
vermin of all sorts, hold him within reasonable bounds and restraint,
and assume responsibility for his acts, on the other hand, the owner-
less dog, the dog which carries vermin and disease, the dog which
kills sheep or destroys property of any sort, the trespasser—these
dogs must be eliminated.

The case against the unrestricted dog is based on two doiinte thes
he is a nuisance and that he is dangerous.

That most dogs are allowed too many liberties and too much
familiarity with people is a matter of common knowledge. Trans-
gressions on the part of dogs range from simple trespass to the habit
of biting without provocation and to the wanton killing of sheep.*

The direct monetary damage done by unrestricted dogs, while great,
is even less important than the indirect harm they work as carriers of
disease. It is the purpose of this paper to show how improperly-
cared-for dogs act as agents in the spread of diseases, particularly
parasitic diseases, affecting man and live stock.

DISEASES AND PARASITES CARRIED BY THE DOG.

Dogs probably play a part in the spread of diseases due to fungi,
such as ringworm and favus, and are sometimes important carriers of
bacterial and filterable-virus infections. In the recent outbreak of
foot-and-mouth disease, it was determined beyond any reasonable
doubt that dogs were responsible in some instances for the spread
of the disease, not only from one farm to another, but from one State
to another. The dog is of primary importance and in many instances
the sole carrier in the case of many dangerous and even deadly animal |
parasites of man and the domestic animals, and is especially notorious
as the carrier of rabies. Some of these parasites depend so absolutely
on dogs as carriers during certain stages of their life history that they
would probably or certainly become extinct if dogs were not avail-
able as hosts. The long list of important diseases and parasites which
are conveyed by the dog to man and the domestic animals and which
are present in this country is as follows: Rabies in man and stock;
hydatid in man and stock; gid in stock (and possibly in man also) ;

1See Farmers’ Bulletin 652, ‘“‘ The Sheep-Killing Dog.”

THE DOG AS A CARRIER OF PARASITES AND DISEASE, 3

muscular cysticercosis, or so-called “measles,” in sheep; muscular
cysticercosis, or “ measles,” in-reindeer; cysticercosis of the liver and
mesenteries in stock; tapeworm in man, especially in children; round-
worm in man; tongueworm in man and stock; and fleas and ticks
which transfer from the dog to man and which may in this way
transmit disease and parasites. The above list is sufficient to show
that the dog is of major importance as a carrier of parasites danger-
ous to man and domestic animals. An elaboration of the list follows.

RABIES.

It has been known for over 2,000 years that what are called mad
dogs, those affected with the disease termed rabies, hydrophobia, or
lyssa, could transmit this disease to stock and to man by biting them.
For 2,000 years the disease has been reported in sporadic and epidemic
outbreaks. It is now recognized as a widespread, acute, infectious dis-
ease of the central nervous system, characterized by extreme nervous
excitability. It is a disease which, if untreated, leads to a certain
death of the most horrible and agonizing sort. It owes its wide dis-
tribution and its very existence almost exclusively to the dog. The
disease may manifest itself in dogs or other animals under the form of
dumb rabies or furious rabies. In dogs there is commonly evidence of
depraved appetite, the dog eating sticks, leather, and stones, and the
finding of such things in the stomach is a suspicious indication of pos-
sible rabies. There is a partial or complete paralysis of the throat, and
the resultant difficulty in drinking is the basis of the erroneous idea
that the mad dog is afraid of water. As a matter of fact, such dogs
‘are often very eager for water but are unable to swallow it. The
disease seems to have some specific effect on the centers controlling
biting, the feature on which transmission of the disease depends, and
not only dogs but such animals as the horse show a tendency to bite
when affected with rabies. The disease is suspected of being due to a
parasitic protozoan, though as yet too little is known regarding this
to warrant a definite statement. An examination of the brain of
rabid animals shows certain cell inclusions known as Negri bodies
(fig. 1), the nature of which is not at present well known.

It has been pointed out in a previous publication* of the United
States Bureau of Animal Industry that rabies is becoming increas-
ingly prevalent in the United States. That publication cites the fact
that the New York Pasteur Institute had treated 1,608 cases of hy-
drophobia during the first 11 years of. its existence, up to 1901.
The Chicago Pasteur Institute, established at about the same time as

1 Rabies and its increasing prevalence. By George H. Hart. Bureau of Animal Indus-
try Circular 129. Washington, 1908.

\

4 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE.

the New York Institute, had treated 3,010 persons for hydrophobia
during the first 17 years of its existence, up to 1907. The Baltimore
Pasteur Institute had treated over 1,000 cases up to 1908. Many _
more such figures could be cited for the numerous other Pasteur

DEST

Wie. 1.—a, b, Nerve cells of the brain, showing Negri bodies, a diagnostic factor in rabies.
1, cytoplasm of cell; 2, nucleus of cell; 3, nucleolus of cell; 4, Negri body in cytoplasm
of cell. (After Hart.)

institutes in this country. In 1908, 111 deaths of persons from
rabies were reported in the United States, and owing to our inade-
quate statistical methods we have nothing like exact data in regard ©
to the extent and distribution of the disease or the number of cases

THE DOG AS A CARRIER OF PARASITES AND DISEASE. 5

and deaths. In 1911, according to Stimson,’ there were 94 fatal
cases in man, a decrease from the figures for 1908, which is probably
due largely to the fact that in 1911 there were 4,625 persons treated
for rabies in this country. Mohler? states that there are only three
States in the Union—Idaho, Utah, and Nevada—from which it has
been impossible to obtain positive information to the effect that cases
of rabies have been found in them. The disease has since been
reported from Idaho and Nevada.

Rabies is an easily preventable disease. In the present state of our
knowledge as to its mode of transmission, there is no reason for its
continued existence. It may be prevented and in time eradicated by
simply muzzling dogs for a sufficient period to allow the disease to die
out. Such a minor restraint on the dog as muzzling was sufficient to
eradicate rabies from England. The first case since 1902 has just been
reported in the spring of 1915, and this case occurred in a dog that was
being held in the six months’ quarantine which is enforced on all dogs
brought into that country to prevent the disease being reintroduced.
Australia and New Zealand have never had any cases of rabies, and
a system of quarantine and inspection is provided to prevent its intro-
duction. It has been practically or completely eradicated from
Sweden, Norway, and Denmark by rigid enforcement of muzzling
ordinances.

HYDATID.

Hydatid disease occurs in man, cattle, sheep, horses, hogs, and |
numerous other animals. It is caused by the presence of the so--
called hydatid (technically known as Echinococcus polymorphus,
Echinococcus granulosus, Echinococcus multilocularis, etc.) in such
tissues as the liver, kidney, muscles, brain, lungs, etc. The hydatid
is a bladder worm or larval tapeworm (fig. 2), and is characterized
by its thick laminated cyst wall. The original bladder frequently
develops daughter bladders cn the inside or‘on the outside, and in |
these or the original bladder there develop brood capsules containing
tapeworm heads. There are probably two species of hydatid, though
they are commonly considered a single species. The bladder worms
are often as large as an orange and may be as large as a child’s head.
Growth and the formation of daughter bladders may go on for an
indefinite period. There have been cases in which hydatids have
existed in man as long as 30 years before the death of the patient
finally ensued, Their presence in the body causes various forms of

1 Rabies in the United States during the year 1911. By A. M. Stimson. Public Health
Reports, vol. 27 (28), July 12, 1912, pp. 1098-1101. :

2Rabies or hydrophobia. By John R. Mohler. Farmers’ Bulletin 449. Washington, |
1911.

6 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE.

hydatid disease, depending on the location of the parasite. The
effects are very serious and the prognosis is always grave. A con-
servative estimate gives a death rate of 13.6 per cent of the persons
infected (Vegas and Cranwell). The growth of the bladder gives
rise to various troubles as a result of pressure, obstruction, perfora-
tion of important organs, necrosis of tissue, liberation of poisonous
products, secondary bacterial infections, rupture of the hydatid, and
secondary hydatid infestation following rupture of the cyst. It is
commonly necessary to resort to surgical interference for the re-
moval of the hydatid. Operation is often very difficult and may
have to be repeated, owing to the presence of small external daughter
bladders which are easily overlooked or incapable of detection. A

¥ic. 2.—Portion of a hog’s liver infested with hydatid bladderworm (Echinococcus
granulosus). Natural size (after Stiles).

case has been recently recorded where the patient had to be operated
on four times before the recurrence due to daughter bladders had
ceased. .

In the lower animals hydatids are probably less often a cause of
death, owing to the slow growth of the parasite and the fact that
the affected animals are likely to be slaughtered before sufficient time
has elapsed for the parasite to become a menace to the life of the
animal.

If brood capsules containing the tapeworm heads are eaten by
dogs—a thing which is apt to occur on farms where the viscera of
slaughtered animals, especially when they appear unwholesome, as
they would in hydatid disease, are thrown out on the fields or fed to

THE DOG AS A CARRIER OF PARASITES AND DISEASE 7

dogs—these tapeworm heads pass uninjured to the intestine of the
dog and give rise to numerous very small segmented tapeworms,
Tenia echinococeus (fig. 3). The dog is practically the only carrier
of this tapeworm. The tapeworm attains a length of only about half
a centimeter (three-sixteenths of an inch) and consists of a head and
three segments. The sexual organs develop in the second segment
and eggs are present in the third segment. These eggs pass out
in the feces of the dog and infect pasture, soil, and water. They
are spread broadcast on grass, in drinking water, on products in-
tended for human food, on children’s toys, and on all sorts of objects
in places frequented by the dog. The rooting habit of the hog
predisposes it to hydatid disease, as it is extremely likely to swal-
low some of these eggs in feeding if there is a
dog with the hydatid tapeworm anywhere around.
But even the most careful persons have no assur-
ance of safety where there are such dogs. Eggs
from the feces of these dogs may wash consid-
erable distances and ultimately land on lettuce,
radishes, or other vegetables. They may get on
the hand from contaminated. tools or farm im-
plements, or from the dog’s skin. Persons who
allow dogs to lick their hands or faces run the
risk of acquiring and ingesting the eggs of this
tapeworm. When such eggs, which are, of course,
too small to be seen with the naked eye, are in-
gested by man or animals, the shell digests off
and releases a small embryo armed with six hooks. 7

By means of these hooks the embryo bores its 0. Bo eumemems
way through the wall of the stomach or intestine echinococcus), the
and into the blood current. Here it is swept oes pices
around till it lodges. At the point of lodgment of adog. Enlarged
the embryo starts to develop into the hydatid or —‘(#*ter_Leuckart).
bladder worm already noted. The parasite must always be trans-
mitted from the dog to other animals by the ingestion of the egg
from the tapeworm in the dog, and from other animals back to the
dog by the dog eating diseased carcasses or parts of carcasses. It
can not be transmitted in the form of the hydatid from an infected
animal to another animal nor in the form of the tapeworm from one
dog to another.

Prevention depends in part on a proper handling of slaughtered
animals and of those dying from any cause. An obvious aid in pre-
venting this disease would be to destroy diseased portions of animals
slaughtered for food or for any reason. This is best accomplished at

8 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE,

our large packing houses where such diseased portions are tanked at
temperatures which insure the destruction of all parasites of any sort.
On the farm it may be accomplished by boiling any viscera before
feeding them to dogs or other animals. The viscera should never
be thrown out on the fields. The practice is objectionable of itself;
it furnishes a breeding place for flies and is in every respect insani-
tary and improper. Viscera and carcasses, if not cooked and fed,
should be burned, buried with lime, or disposed of in such a snanner
that they can not be devoured by dogs.

An additional method of preventing hydatid disease, and the one
that should be emphasized here, is for the owners of dogs to keep
them up, and to have stray dogs disposed of by the proper authorities.
A person should have substantially the same supervision of his dog’s
food, for his own sake and for the sake of the dog, that he has of his
children’s food. It is dangerous as well as unwholesome to allow dogs
to forage for a living. A man who does not properly feed his dogs
has a poor claim to their care and ownership. Dogs should be kept
out of human habitations and treated in general with more regard to
their possibilities as disease carriers.

Hydatid disease is fairly common in Europe. It is quite common in
Iceland, India, Eastern Siberia, Algeria, Tunis, Australia, and some
South American countries. It has been permitted to assume the pro-
portions of a serious menace in Australia, and 3,000 cases of hydatid
disease in human beings were reported from there between the years —
1861 and 1882. In at least two South American countries hydatids
are so common that the sanitary authorities have issued illustrated
placards warning against the disease.

Over 240 cases of hydatid in man have been recorded from the
United States up to 1902. Over most of the United States hydatids
are comparatively infrequent in domestic animals, but they are not
so rare that they are curiosities to meat inspectors. Numerous con-
demnations of organs and parts of carcasses are reported every year
from the various meat-packing establishments under Federal inspec-
tion. Some recent abattoir figures show an alarming prevalence of
this disease in domestic animals in some parts of this country, notably
in certain localities in Virginia, Arkansas, and Oklahoma; and the
prevalence of hydatids in domestic animals is an index of the danger
to which people are exposed. It is, moreover, desirable that we apply
preventive measures before a larger list of cases in man makes both
curative and preventive measures imperative. The bare fact that
hydatids occur at all in the United States is of itself a cogent argu-
ment for the suppression of the dog nuisance as a measure necessary
for the public welfare.

THE DOG AS A CARRIER OF PARASITES AND DISEASE. 9
GID.

Gid disease, like hydatid disease, is due to the presence of a blad-
der worm, or larval tapeworm, in the tissues. The bladder worm
(known as Multiceps multiceps or Cenurus cerebralis) (fig. 4) which
causes gid resembles the hydatid bladder worm in that one bladder
worm may produce large numbers of tapeworm heads, and the tape-
worms resulting from these heads occur in the intestines of dogs.
as in the case of the hydatid tapeworm. The bladder worm caus-
ing gid differs from the hydatid in that it has a thin, delicate,
membranous wall in-
stead of a thick lam-
inated wall; it does
not produce daughter
cysts as the hydatid
does, and it occurs
only in the brain
and spinal cord in-
stead of in any tis-
sue. The adult tape- b_..
worm in the dog,
commonly known as eens 4
Tenia cenurus (fig.
5) attains a length
of 2 or 3 feet instead
of a small fraction of
an inch.

Gid is principally
a disease of sheep,
though it is fairly
common in cattle and

there are some cases ri. 4.—Brain of giddy sheep, showing gid parasite, a, Gid
from the horse and parasite or bladder worm; b, heads on bladder worm.

the goat. Th 1910: (After Numan, 1850, Pl. I, fig. 1.)

the writer stated that there were no valid cases of the disease in
man. Since then Brumpt? has published one case which apparently
must be accepted as a good case.

The life history of the gid parasite is practically the same as that
of the hydatid. The gid bladder worm is called a conurus. When
this coenurus is eaten by a dog, the tapeworm heads on the ccenurus
pass to the intestine of the dog and give rise to a tapeworm which °

1The gid parasite and allied species of the cestode genus Multiceps. 1, Historical
review. By Maurice C. Hall. Bureau of Animal Industry Bulletin 125, pt. 1.
2Précis de parasitologie, 2d ed., pp. 281-283. 1913. :

94288°—Bull. 260—15——2

10 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE.

may attain a length of 2 or 3 feet. In the terminal segments are
eggs, and these segments with the contained eggs pass out in the
feces of the dog and contaminate vegetation, soil, and water. Such
herbivorous animals as sheep, which graze over range or pasture
contaminated in this way, pick up these eggs as they feed and swal-
low them. In the stomach of the sheep the shell is digested and
the small, hooked embryo released. The embryo bores its way
through the wall of the digestive tract and into the blood vessels
and is carried around until it lodges
somewhere. Embryos which do not
lodge in the central nervous system
start to grow, but very soon perish.
Very commonly, however, the para-
site makes its way to the central
nervous system, lodging as a rule in
the brain, though it occasionally oc-
curs in the spinal cord. In the brain
the embryo grows to form the blad-
der worm or ceenurus, and this may
attain the size of an egg, or even a
larger size. As it grows it presses
upon the adjacent portion of the
_ brain and destroys it. The pressure
and the irritation, due to the hooks
with which the tapeworm heads of
the ccenurus are provided, cause very
distinctive symptoms, the sheep com-
monly holding its head in an odd
position and walking in a circle
toward one side or the other. Un-
less the ccenurus is removed by oper-
ation the sheep invariably dies.
Fic. 5.—Adult gid tapeworm from the When the brain of such a sheep a
dog. Natural size. (Specimen No. eaten by dogs—and dogs very read-
sage a cies calle aes Industry jly eat the brains of sheep by licking
them out through the large opening
at the base of the skull—the ceenurus is ingested with the brains
and the tapeworm heads pass to the intestines of the dog and give
rise to the adult tapeworms. As in the case of the hydatid, the gid
parasite must always be transmitted from the dog to other animals
which eat the eggs from the dog tapeworm, and from the other ani-
mals to the dog by the dog eating the brain or at least:the conurus
from the brain of a giddy animal.

THE DOG AS A CARRIER OF PARASITES AND DISEASE. 11

One preventive measure for suppressing gid is, of course, to destroy
the brains gnd the ceenuri of giddy animals, which can be done by
burning them or by breaking the skull and covering the brain with
formaldehyde, sheep dip, or some similar substance. Another meas-
ure is to administer a vermifuge to sheep dogs and so rid them of
their tapeworms, and to do this often enough to keep them free
from tapeworms. But it is obviously of little avail to a sheepman
to have his own dogs free of tapeworm if his neighbor’s dogs or
ownerless dogs or strays of any sort are free to carry tapeworm
onto his range or pasture and infect the grazing and thereby infect
his sheep. From losses originating in this way he must be pro-
tected by measures looking to the restraint of dogs that recognize
an owner and the elimination of those that do not.

Gid has been reported from several States in this country, but. it
is most prevalent in Montana, especially in the northern half of
that State, where gid has had a foothold for a quarter of a century
and where the losses for some years total about $10,000. There is
evidence of the occurrence of gid in Arizona, and outbreaks have
occurred in recent years in New York, Iowa, and Kansas. There
have been reports, apparently correct, of its occurrence in Ohio,
Illinois, Michigan, Missouri, Oklahoma, and Nevada. It is a con-
stant source of loss in many European countries, and at various
times has proved a veritable scourge to the sheep industry of these
countries.

CYSTICERCUS (MEASLES) IN SHEEP AND OTHER ANIMALS.

Muscular cysticercosis: (“measles”) in sheep——The presence of
small bladder worms in mutton has recently been shown by Ransom?
to be much more common than had been suspected, and.to be due to.a
tapeworm in the dog and not to a tapeworm of man as had been
supposed. His investigations showed that under careful inspection
the percentage of affected sheep in this country has amounted to 2
per cent or more, and that approximately 20,000 sheep carcasses were
retained in 1912 in abattoirs under Federal inspection on account of
“sheep measles” due to this parasite.

The bladder worm, Cysticercus ovis (fig. 6), in the meat of ices
is oval and ranges in size from about one-third of a centimeter (one-
eighth of an inch) to almost a centimeter (three-eighths of an inch)
in length. Inside of this bladder there is a single tapeworm head,
in which respect, as well as in size, this cysticercus, as it is called,

1 Oysticercus ovis, the cause of tapeworm cysts in mutton. By B. H. Ransom. Journal
of Agricultural Research, U. S. Department of Agriculture, vol. 1, pp. 15-58. 1913.

12 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE.

differs from a hydatid or a coeenurus. Numerous cysts, however, may
-bé scattered through the musculature, so that in their numbers there
is’ a: compensation, so to speak, for their small size and lack of a mul-
tiplicity of heads. Inasmuch as the presence of these cysts calls for
condemnation. of a part or all of the infested carcass, according to
the degree of infestation, and the number of carcasses amounts to
20,000 a year; this parasite has considerable economic interest for

Fie. 6.—Bladder worm (Cysticercus ovis), a tapeworm cyst infesting the meat of sheep.
(From Ransom.)

this country, and never more than at the present time when the
“high cost of living” is such a vital topic.

-When one of these cysticerci from mutton is ingested by a dog,
the tapeworm head passes undigested to the dog’s intestine and
develops into a fairly large tapeworm, comparable to the gid tape-
worm. Similarly, this tapeworm, Tenia ovis (fig. 7), produces eges
which are passed out in the feces of the dog, and which are ingested

THE DOG AS A CARRIER OF PARASITES AND DISBASE. 13

by sheep as they graze over range or pasture or drink water con-
taminated by these feces. In the sheep the eggshell is digested, the
released embryo bores through the tissues and comes ‘to rest usually
in the edible musculature, and the bladder worm develops to the
cysticercus capable of again infecting the dog. In cases of heavy
infestation sheep are liable to die in the course of two to three weeks,
but as a rule the health is not perceptibly affected. Here, as in all
similar cases, the parasite must pass from the dog to the sheep -and
from the sheep to the dog.

Fie. 7.—Tapeworm (Tenia ovis) developed by feeding bladder worm. “(Cysticerous, welds
to a dog. (From Ransom.)

The parasite has been found in Europe, Africa, and New Zealand.
It has been found thus far in seven States in this country. It appears
to be particularly prevalent in the West, a fact that. is’possibly re-
lated to carelessness on the part of the western sheepmen as regards
the disposal of carcasses of sheep dying on the range. Such ‘sheep
are usually left lying where they die, a practice which aids in the
spread and continuance of gid, and which serves the same purpose
in the case of the “sheep measles” parasite that-throwing diseased.
viscera of hogs onto the fields does in the case of the hydatid para-
site. The sheep dog is probably the principal carriet’ ‘of tHe pasate,

ees Gated Paar e!

14 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE.

so that neglect on the part of sheep owners is a leading reason for
its prevalence.

The prophylactic measures against “sheep measles” are essen-
tially the same as those against gid and hydatid. Diseased portions
of slaughtered sheep and dead sheep which have not been slaughtered
should be cooked before being fed to dogs or else disposed of so that
dogs can not eat them. Ownerless dogs should be destroyed and other
dogs properly fed and kept free from tapeworm.

Muscular cysticercosis (“measles”) in reindeer—This parasite
deserves special mention in view of the possibility that the Alaskan
reindeer may become important in connection with the meat supply
of this country. A large percentage of these animals, which are
rapidly increasing in numbers, are infested with a measle parasite
apparently the same as the form known to be the
intermediate stage of a dog tapeworm (Tenia
krabbet). This is not only serious so far as con-
cerns the reindeer industry, but the possibility that
the parasite may become established in other food
animals is not altogether excluded, though prob-
ably remote. Tenia krabbei occurs.in Europe and
Asia and was likely introduced with the reindeer
or dogs imported into Alaska, though the Alaskan
form may be a native parasite ulready present in Fic. 8—Cysticercus
American reindeer and carnivores before the im- {py “ico!it#: the
portation of the Old World animals. der worm from
— Cysticercosis of livers and mesenteries—Cysti- 2.78 ese
cercosis, or the presence of cysticerci, or bladder swine, ete. Natu-
worms, in the livers, mesenteries, and omentum or aa fares
“ fat caul,” is very common in cattle, sheep, and hogs
throughout the United States. These bladder worms, Cysticercus
tenuicollis (fig. 8), are usually 1 or 2 inches in diameter, and the
cyst contains a single tapeworm head. The life history follows
the same general plan that has been outlined for the preceding tape-
worms. When such bladder worms, or viscera containing them, are
eaten by dogs, the head contained in each cyst passes to the intestine
and develops a tapeworm (Tenia hydatigena or Tenia marginata)
(fig. 9) in the dog; the eggs produced by the tapeworm pass in the
feces of the dog onto the vegetation or into the drinking water of
cattle, sheep, and hogs; the eggs ingested by these animals in feeding
or drinking release an embryo which makes its way, via the portal
system, from the digestive tract to the liver; in the liver the embryo
develops into a small bladder worm (Cysticercus tenuicollis) which
after some time slips from the liver into the body cavity and lodges
in the omentum or mesenteries, where it attains its final growth; the
bladder worm may then be eaten by a dog, on the death of the host

THE DOG AS A CARRIER OF PARASITES AND DISEASE. 15

animal in which the bladder worm oc-
curred, and will give rise to a large tape-
worm, which may attain a length of 5
meters, or about 16 feet.

Extensive burrowing of the parasites
in the substance of the liver during the
early period of the bladder-worm devel-
opment may cause serious damage, and
in cases of heavy infestation may result
in the death of the animal. Bacterial in-
fection may complicate the parasitic in-
vasion. In the United States, flocks of
sheep in which this parasite is not pres-
ent are rare, and a high percentage of liv-
ers, especially lamb livers, are condemned
in abattoirs under Government inspection
because of infestation with this parasite.

Prevention calls for a proper disposal
of the viscera of slaughtered animals
with a view to keeping the viscera, un-
less first properly cooked, away from
dogs. It also calls for a routine tape-
worm treatment for dogs, an adequate
knowledge and supervision of the food
and feeding habits of dogs, and the elim-
ination of the dog without a responsible
owner.

TAPEWORMS, ROUNDWORMS, ETC.

Double-pored tapeworm—Of the nu-
merous species of tapeworm occurring in
the dog, many of them not mentioned in
this paper because they do not have a
larval stage or bladder worm in man or
stock, one species may occur in man in
the form of the adult tapeworm. This
species, commonly known as the double-
pored tapeworm (Dipylidium caninum),
has a life history which follows the same
general plan of alternation, from a tape-
worm in the dog to a larval tapeworm
in an intermediate host and back ic

bead”

the dog, that the tapeworms already me. 9.—Tenia hydatigena, the

mentioned follow. It is, however, pe-
culiar in that the intermediate stage,

adult tapeworm from the in-
testine of the dog. Natural —
size (after Stiles).

16 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE.

or larval tapeworm, is very small and develops in the dog flea
or louse instead of such an animal as the sheép. The flea or louse
ingests the eggs of the tapeworm by biting the skin of the dog
where it is contaminated by the feces of the animal or by soil
containing eggs from the feces, or possibly by biting the tape-
worm segments containing the eggs as these segments pass from
the dog. Within the flea or louse the egg develops into a larval
tapeworm, necessarily a very small larva, known as a cryptocystis.
Owing to the pain and irritation resulting from the bites of these
fleas and lice, the dog will from time to time root out the offenders
and inadvertently or intentionally, as the case may be, swallow them.
In the stomach of the dog the fleas and lice are digested and the little
tapeworm larva set free to pass on to the intestine and develop into
a tapeworm, which may attain a length of 35 centimeters, or about
14 inches.

When flea-infested or lousy dogs are allowed unwarranted privi-
leges in the house, permitted to put their paws on the table during
meals, to eat from the same dinner plates and saucers, to lick the
baby’s face and the children’s candy, to sleep at the foot of a person’s
bed or on a pillow near a person’s head, the chance of a flea landing
unperceived in food that will hold and conceal the flea, the chance of
its getting to the baby’s mouth or adhering to the sticky candy which
the child eats with no regard to incidental contamination, is very
good. Under such conditions the ingestion of fleas or lice infested
with the larval tapeworm in question is likely to occur, and the result
is the development of the adult tapeworm in the person ingesting
them. This tapeworm has been found in children more frequently
than in grown persons, in one case in a baby only two months old, but
it has been found in an adult 38 years old. As many as 238 worms
have been found in a-single person. Up to date, 76 cases of this tape-
worm in man, usually in children, have been reported, and a number
of these are from the United States.

The remedy here concerns the family dog rather than the stray.
The dog should be treated like a dog, not like a person. The dog
is an animal with its habits fixed by all the facts that arise from the
one fact that it is a dog. The fact that a dog is not a person, that
it is different from people, is important. The lack of hands compels
the dog to use his tongue for a wash rag, but we are under no such
necessity, and there is nothing in the situation that calls for our per-
mitting our own or our neighbor’s dog to use the same tongue sub-
sequently on our hands or face. It is an absurdity to ask that the
cook and the table service be clean and then allow a dog to put his
feet on the table, to sniff at the food, to lick the hand or face, and to

THE DOG AS A CARRIER OF PARASITES AND DISEASE, 17

do the dozens of other dangerous and improper things that some dogs
are allowed to do.

The presence of one or a few of these tapeworms in man probably
occasions very little inconvenience as a rule. At the same time the
tapeworm has an unpleasant habit of burrowing through the intesti-
nal mucosa, thereby destroying its integrity and exposing it to the
attack of any pathogenic germs that may be present in the intestine.
The same burrowing habit makes it difficult to remove successfully
the entire worm with the head, and a failure to remove the head,
owing to its being buried in the mucous lining of the intestine, results
in the subsequent development of new tapeworm segments from the
head and a renewal of infection. At its best, a tapeworm is a thing
unpleasant to contemplate as an inhabitant of our intestines. The
presence of the tapeworm under discussion here is, moreover,
evidence of careless or unclean habits on the part of the person
infested.

Prevention requires that the unwarranted liberties and freedom of
the dog be curtailed; that he be kept free not only from tapeworm
but from such external parasites as fleas and lice. The accomplish-
ment of the latter measure calls for keeping a dog clean and restrain-
ing him so that he will not be allowed to run at large with vagrant
flea-infested and lousy dogs.

Roundworm.—Among the other parasites of the dog there is a
mematode or roundworm, scientifically Inown as Towascaris limbata,
which, like the tapeworm just mentioned, may occur in man in the
same form in which it occurs in the dog. This worm does not have
an intermediate stage in another animal, but is conveyed directly
through the eggs produced by the female worm, which eggs normally
convey the infection from a dog back to the same or another dog,
either in contaminated food or water or as the result of the con-
tamination of the skin and the subsequent cleansing of the skin by
means of the tongue.

Under the conditions of unwarranted association and familiarity
with dogs already mentioned, eggs of this parasite and of an allied

parasite in the cat may be ingested by man, and especially by chil-
dren, and subsequently develop into the adult worm in the intestine.
These worms may produce unpleasant results. The entire group of
ascarids are notorious for their wandering habits. They not in-
frequently travel to the stomach and produce vomiting, in the course
of which the worms may be brought up. It is hardly necessary to
say that the vomiting of worms 4 or 5 inches long is a distinctly
unpleasant experience, and this is one of the least unpleasant results

18 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE.

of such infestation. Ascarids at times enter the appendix and cause
appendicitis; they may perforate the intestine and cause peritonitis;
they may come up the esophagus and get down the windpipe, with a
resultant suffocation, or enter the eustachian tube of the ear. These
are unusual cases for the most part, but they are dangers to be con-
sidered. There are other unpleasant and dangerous features of
ascarid infestation, and the uncomfortable certainty that their pres-
ence is undoubtedly indicative of fecal contamination of food, drink,
or ingesta of some sort.

The prophylaxis in this case, as in the case of the previously men-
tioned worms, depends on keeping dogs free from worms and restrict-
ing their privileges in the household and in their relationship to
human beings.

Fic. 10.—Head of a dog split in half to show three tongueworms (Lingue-
tula rhinaria), a, in the nasal cavity. Reduced in size (after Colin).

Tongueworm.—The tongueworm, Linguatula rhinaria (Linguatula
serrata) (fig. 10), occurs in the adult stage in the nasal passages
and frontal sinuses of the dog. It is light colored and shows an
external, ringlike segmentation. The male may attain a length of
20 millimeters (about three-fourths of an inch) and the female may
attain a length of 100 millimeters (about 4 inches). The eggs de-
posited by the female leave the nostrils of the dog in the catarrhal
secretion occasioned by the presence of the parasite, some of them
doubtless being sneezed out, and contaminate the vegetation on
which they at times lodge. Such vegetation may be eaten by cattle,
sheep, horses, or swine, or if the infested dog has access to a truck
garden or a family vegetable garden, contaminated lettuce, cabbage,
etc., may be eaten by man. When the eggs get to the stomach the
shell is digested off, releasing a peculiar embryo which shows by its
structure that these tongueworms are really related to the mites, a
group of spiderlike animals. This embryo makes its way through

THE DOG AS A CARRIER OF PARASITES AND DISEASE. 19

the walls of the intestine and encysts in the lungs, liver, kidney,
lymphatic glands, etc., where it develops to the larval stage (fig. 11).
Subsequently they break out of their cysts and resume their migra-
tions, wandering through the tissues, causing more or less damage,
until they reach the abdominal or thoracic cavity, sometimes enter-
ing the intestines and bronchj, and at times causing the death of the
host. Just how they get from here to the nasal passages of the dog
is not very well known, though it is certain that this takes place.
Possibly larve are at times sniffed up by the dogs as they nose
through an infested carcass; possibly in eating such a carcass larve
pass directly from the mouth of the dog back to the posterior por-
tion of the nostril by way of the pharynx, or the parasite may re-
turn from the stomach by way of the esophagus. The adult worm
has been reported, but very rarely, from the nasal
passages of man. ;

The larve are apt to be overlooked in necropsies
on the human cadaver, but have been recorded in
as high as 25 per cent of necropsies. In various
localities in Germany they are commonly present
in 8 to 4 per cent. This is a widely distributed
parasite, and is found from time to time in the
United States. A case in man has been recorded
from the Canal Zone.

Prevention consists in keeping viscera of ani-
mals away from dogs, unless the viscera are cooked,
and in a reasonable attention to what a dog eats,

and this involves a responsible supervision of the %. 11-—Linguatula
rhinaria, the larval

dog’s wanderings and conduct in all respects. Saibuenonia * roi
the liver and lymph

FLEAS AND TICKS. glands of cattle,

sheep, etc. En-

Fleas—In the western United States investiga- larged ten times

e ‘i a : (after Railliet).
tions indicate that the commonest flea attacking

man is the so-called human flea, Pulex irritans, of which man is the
primary host. The same investigations indicate that the dog is a
most important carrier of that flea, probably the most important.
Of 456 fleas collected from dogs in Berkeley, Cal., 29 per cent were
of this species. In the eastern United States investigations indicate
that the commonest flea attacking man is the so-called dog flea,
Ctenocephalus canis (fig. 12), and here, of course, the dog is the
normal host and the usual carrier.

Either species of flea constitutes an annoying pest. The bite is
distinctly unpleasant and in the summer nights may prove just the

20 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE.

additional irritant which makes sleep impossible. Equally as im-
portant as the annoyance is the fact that fleas of all sorts are under
suspicion at present as possible carriers of bacteria, parasites, and
diseases of various sorts. We know that the dog flea and the human
flea, as well as the rat flea, are capable of transmitting bubonic
plague to man; that the dog flea, as already noted, transmits the
tapeworm Dipylidium caninum to man; and we are warranted in
suspecting that additional study will add other counts to this indict-
ment against fleas. In the meantime our actual knowledge and strong
suspicion are ample grounds for avoiding fleas and the flea-bearing

Fic. 12.—Dog flea (Ctenocephalus canis): a, Egg; b, larva in cocoon; c, pupa; d, adult;
e, raouth-parts of same from side; f, antenna; g, labium from below. b, c. d, Much
enlarged; a, e, f, g, more enlarged. (From Howard, Bureau of Entomology.)

dog. It is comparatively easy to avoid annoyance from fleas in the
absence of dogs or cats around a dwelling. Where dogs and cats are
present it is more difficult and the animals must be closely watched
and given appropriate treatment from time to time. For adequate
protection it is essential that stray dogs and dogs belonging in the
neighborhood should be prevented from becoming habitual visitors
and utilizing the porch and hammock as sleeping quarters.

The chicken flea (Hchidnophaga gallinacea), a common pest in
some of the Southern States, frequently infests dogs. Here, again,
the remedies lie in the proper handling of dogs by their owners and
the elimination of ownerless dogs or dogs whose irresponsible owners

THE DOG AS A CARRIER OF PARASITES AND DISEASE. 21

take no care of them. Under proper conditions of restraint dogs
may be rid of fleas and kept free from them.

Ticks—In this country the dog is known to be the usual or occa-
sional; carrier of 11 species of ticks, almost all of which are also
occasional or habitual parasites of man
or stock. In this way the dog serves
the tick by furnishing it with nourish-
ment ,and also aids in spreading in-
festation, conveying ticks in this way
to man much more effectively than
other animals are able to do, for the
reason that there is no other animal
in such close contact with man, with
so many liberties, and with such a wide
and unrestrained range during the
periods when it is not with its owner. '!. 18.—American dog tick (Der-
These habits of the dog make it an epee aes ve q ‘Ho oe
object of suspicion in connection with Rd Bey Wood, Bureau of
tick-eradication work. Such ticks as ;

Dermacentor variabilis (fig. 13), which are common on the dog, are
brought into houses rather frequently and have many opportunities
to attack man. Such ticks as the spotted-fever tick, known as Der-
macentor andersoni ov Dermacentor venustus (fig. 14), are seldom
found on dogs, but in view of the
fact that the bite of one tick may
result in spotted fever and the death
of the person bitten, even such in-
frequent transmission by dogs must
be guarded against. This tick is
known to occur in Montana, Wyo-
_ ming, Colorado, New Mexico, and
the States west of these, with the
exception of Arizona. Spotted fever
is known to occur in a number of
these States, and with the tick pres-
Fic.. 14.—Rocky Mountain spotted- ent its occurrence and spread in the
mas ede ie aa other States depend merely on the
sal view. (From Hooker, Bishopp, chance of a carrier of some sort com-
and Wood, Bureau of Entomology.) a 7 on :
ing into them under conditions which
will permit of the tick having access to the carrier and to other ani-
mals or persons. Dogs may also carry the Texas-fever tick (Mar-
garopus annulatus), and some species of ticks possibly depend on the
dog for their continued existence.

aes

22 BULLETIN 260, U. 8. DEPARTMENT OF AGRICULTURE.

Dogs which are kept free of such vermin as ticks by frequent baths
or other necessary measures and which are not allowed to wander
at will are reasonably safe from the standpoint of spotted fever or
other tick conveyance to man or stock. They are at least much safer
than those which are neglected, allowed to accumulate internal and
external parasites, and to carry and convey the same without
hindrance.

MISCELLANEOUS PARASITES.

In the foregoing part of this paper only those injuries, parasites,
and diseases traceable to the dog which are known to occur in the
United States have been mentioned. It should be stated, however,
that the dog is known to have quite a large number of other para-
sites, some of them already, present in this country, which have been
found in man and stock in foreign countries, sometimes as rare and
unusual occurrences and sometimes very common and even in the
form of endemic, constantly present diseases. Inasmuch as almost
all of the parasites heretofore mentioned originated in foreign coun-
tries and were brought here, and since we have no guaranty and
but little protection against others being brought here, it will be
worth while to name some of the other parasites of which space for-
bids a detailed discussion. Some of the parasites mentioned below
have been found in the dog only as a result of experimental infesta-
tion, which is, however, proof that they might occur in nature under
suitable conditions of transmission. Some of these diseases, owing
to the nature of the life history, possibly could not obtain a foothold
in this country, but many of them certainly could.

Protozoa.—The dog has been reported as a carrier of the following
protozoa: E’'ntamaba dysenteriae, the cause of amebic dysentery in
man; Lamblia intestinalis, a flagellate protozoan which is rather
common in man in the United States; Trypanosoma evansi, which is
the cause of surra, a disease of horses, cattle, etc., which has not yet.
been introduced into this country, but which has been detected at the
quarantine station and kept out of the country by the United States
Bureau of Animal Industry on one occasion; Trypanosoma brucei,
which is the cause of nagana, a disease of horses, cattle, etc., which
occurs in Africa; Z’rypanosoma equinum, which is the cause of mal de
caderas, a disease of horses in South America; 7rypanosoma dimor-
phon, which causes a disease of horses, cattle, etc., in Africa; Try-
panosoma pecaudi, which is the cause of baléri, a disease of horses in
Africa; Nuttalia tropica, which is the cause of a piroplasmosis of
horses and cattle in India; Leishmania furunculosa (L. tropica),
which is the cause of Oriental sore, a disease of man which has re-
cently been reported from this continent at Panama;! Leishmania

1 Oriental sore in Panama. By 8. T. Darling. Arch. Int. Med., Chicago, v. 7, May,
1911, pp. 581-597.

THE DOG AS A CARRIER OF PARASITES AND DISEASE. 23

infantum, which is the cause of infantile splenomegaly, a serious,
commonly fatal disease of children in Italy and Tunis; Leishmania
donovani, which is the cause of tropical splenomegaly, a serious dis-
ease of adults in India, China, and the Sudan; Leishmania bra-
ziliensis, which is the cause of a disease of man in South America;
Spirocheta aboriginalis, which is the cause of granuloma inguinale
in man in British Guinea and Australia; and of some other protozoan
forms of which the record or the identity of the form in the dog
with those in man or stock is still uncertain. A useful object lesson
may be drawn from the fact that the destruction of stray dogs in one
small island in Italy has resulted in a remarkable reduction in the
prevalence of infantile splenomegaly in that locality. This terrible
disease is apparently spread from dogs to children by fleas.

In addition to the above-mentioned protozoa there are a number
of worm and arthropod parasites carried by the dog and attacking
man or the domestic animals, which have not been discussed in the
first part of this paper because of their absence from or comparative
infrequency or unimportance in this country. A brief note of these
forms is given here.

Tapeworms.—As regards tapeworms, the dog shares with man the
responsibility for carrying the broad fish tapeworm, Diphylloboth-
rium latum (Dibothriocephalus latus), a tapeworm of considerable
medical importance, which is known to be established in this country,
and both carry an allied tapeworm, Diphyllobothrium cordatum.
The dog is also an occasional host of the pork measle parasite (Cysti-
cercus cellulose), the larve of one of the tapeworms of man. The
dog becomes infested with this parasite by eating the feces of the
human host of the tapeworm. It has also been shown to act as the
host of an adult tapeworm having a Sparganum larva in the hog, and.
may be the host of other related tapeworms belonging to this group.

Flukes—The dog is reported as the carrier of the following flukes:
Paragonimus kellicotti, which occurs in the lungs, causing para-
sitic hemoptysis in hogs in this country; Clonorchis sinensis and
Clonorchis endemicus, which occur in the liver of man and hogs in
China and Japan; Heterophyes heterophyes, which occurs in the in-
testine of man in Japan and Egypt; Dicrocelium dendriticum
(D. lanceatum), which occurs in the bile ducts of man and of horses,
cattle, sheep, hogs, etc., and which is common in various foreign
countries, though not as yet known from the United States; Schisto-
soma japonicum, which occurs in the blood of man in Japan, China,
the Philippines, and South Africa; Opisthorchis felineus, which oc-
curs in the liver of man in Asia; and of Opisthorchis noverca and
Pseudamphistomum truncatum, also parasites of man.

Nematodes.—As regards nematodes, the dog is one host of Dracunc-
ulus medinensis, the Guinea worm, which is not known in this

24 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE.

country, and is the usual host of Dioctophyme renale, the giant kid-
ney worm, which is a huge red worm a yard long and as thick as a
little finger, occurring in the kidney or abdominal cavity of man, the
cow, the horse, and the hog. This last-named worm has been found
in this country on a number of occasions. Strongyloides stercoralis,
the parasite of Cochin China diarrhea, can be readily transmitted to
dogs, and a Strongyloides, apparently this species, is found in dogs
in China and Japan.

Mites, fleas, etc-—The dog is affected by a form of mange or scab
due to a mite known as Sarcoptes scabiei canis. This disease occurs
in this country and may be transmitted to man, causing more or less
discomfort. The dog is also known to be attacked by and transmit
the sarcoptic scab of sheep, a rather rare form of scab due to the mite
Sarcoptes scabiei ovis.

In addition to being the adult host of the aberrant spiderlike form,
Linguatula rhinaria, the larva of which may occur in man, the dog is
a host for the larval form of two closely related species, Porocephalus
armillatus and P. moniliformis, which may also pass their larval
stage in man.

The dog is not only a host for the cosmopolitan fleas Pulea irritans
and Ctenocephalus canis, but is also a host for the widely distributed
chigger flea, or chigoe, Dermatophilus penetrans (Sarcopsylla pene-
trans), of tropical countries and native in the southern portion of
North America. This flea attacks men, cattle, horses, mules, sheep,
goats, and hogs, the female becoming embedded in the skin and grow-
ing to the size of a pea. :

Finally, the dog is an important host of the parasitic larve of .
certain flies which also habitually attack human beings and live
stock. One species, Dermatobia cyaniventris, occurs in South and
Central America, and another, Cordylobia anthropophaga, occurs in
Africa. These larve undergo their development beneath the skin,
causing boil-like tumors and abscesses. Another species, Paralucilia
macellaria (Chrysomyia macellaria) , is a serious pest in the southern
United States. Its larve, commonly called screw worms. attack
cattle, horses, and other animals, including dogs and human beings.
These screw worms may undergo their development in the carcasses
of dead animals as well as in the tissues of live animals.

CONCLUSION.

The parasites discussed in this paper do not nearly exhaust the list
of those present in the dog, but only those known also to affect man
or live stock.

In conclusion it may be said that the dog is at present the subject:
of numerous criticisms from three quarters. For over half a century

THE DOG AS A CARRIER OF PARASITES AND DISEASE. 25

parasitologists have been insisting that the dog is so largely respon-
sible for the spread and so essential to the existence of so many im-
portant parasites that we must curtail his liberty and guard him,
ourselves, our families, and our stock from the evil results of his
unrestrained wanderings.

For a number of years public-health officers and others who have
the welfare of the community at heart have been insisting on a re-
striction of the dog’s unwarranted liberty in order to lessen and in
time to eliminate the terrible menace of rabies.

More recently the sheepmen who have been accustomed to keeping
out of business in localities where there were too many dogs, or who
have permitted themselves to be forced out of business as a result of
the attacks of sheep-killing dogs and the resentment and antagonism
of the dogs’ owners, have been .taking more aggressive action and
have started a propaganda looking toward the elimination of the
worthless dog and the placing of full responsibility for other. dogs
on their‘owners. .

It is to be hoped that the coordinate action of these persons and
others interested in the safeguarding of life, health, and property
will soon bring about positive and valuable results.

In a general way there are three kinds of dogs—the vagrant,
ownerless stray; the other person’s dog; and your own dog.

The stray dog which recognizes no owner must be eliminated. The
irresponsible dog with no owner to care for him, to look after his
health as it concerns the dog and other animals and man, and to re-
strain him and stand sponsor for his acts and especially the damage
he may do—such a dog does not fit into a scheme of civilization which
is based on law and the responsibility of individuals for themselves
and others.

We have a right to insist, and should insist, that the other person’s
dog keep off our premises. A dog that is allowed by the owner to
wander at large will have substantially the same habits of life, the
same sort of food, and be substantially as dangerous as the ownerless
dog. Such a dog is not only a trespasser but a potential menace whose
visits may incur loss of money, health, or even life.

Your own dog should be handled in such a way as best to further
the welfare of the dog and the community. He should be kept in
restraint and not allowed the full freedom of the house or even of
the outside premises. He should not be allowed to be familiar with
people, and especially with children. The dog should be kept free
from external parasites by frequent baths and, if necessary, other
appropriate measures, and should be freed from internal parasites by
suitable measures and kept free by adequate attention to his food. He
should only be allowed to leave the yard or the kennels in company

26 BULLETIN 260, U. 8. DEPARTMENT OF AGRICULTURE.

with some person, and wherever conditions call for it should be kept
in leash. When away from home the dog should be muzzled with a
reliable metal muzzle, not with a strap muzzle that would be cruel to
the dog if tight enough to be effective and which is usually so loose as
merely to give a false sense of security, since it permits the dog to bite.
_ In regard to laws requiring muzzling and other restraints,
Schroeder? has made the following interesting comment:

The reason why laws of this nature have not been made is due to the active
fight against them by a small, greatly interested minority that opposes a tardy,
disinterested majority. The minority fights hard for a privilege it has long
enjoyed and abused, that of allowing dogs to be at large without restraint at
all times, and the majority has never half realized that this privilege is costing
a high price in the destruction of property and in horrible agony and numerous
deaths. * * * The dog owner who knows what rabies is from experience,
if he has the proper consideration for his own welfare and that of his dogs,
will be among the first to demand a movement for its suppression, even if this
should place restrictions on the freedom of his own dogs. His interest is
greatest because he has the most at stake and is himself most seriously and
frequently exposed to the infection.

As means or adjuncts for attaining the conditions outlined here,
numerous measures have been suggested and, to some extent, practiced
in this country. Some of these measures are cited in a paper by
Stimson,? and a very good summary has been given by him. Among
the possible measures are, of course, the imposition of a license on all
dogs, dogs so licensed to wear an official tag with at least a registered
serial number on it, and possibly with the owner’s name and address
also. Any dog not so licensed should be taken up by an adequate
impounding force and humanely killed. Dogs so licensed should be
taken up when found astray in violation of ordinances requiring
muzzling or imposing other restrictions. Rabies should be made a
reportable disease everywhere, and prompt and thorough measures
taken for its eradication, to be followed by quarantine against unre-
stricted importation of dogs into clean areas. Castration and spaying
are recommended as aids in keeping a dog at home. They also serve
to stop the promiscuous breeding which serves to add recruits to the
vast army of worthless and vagrant dogs. Dr. Arbuckle, in recom-
mending castration, says that it does not diminish the animal’s value
as a hunting dog.

Protection from the dangers of improperly controlled dogs depends
primarily on the education of the public and the development of an
educated public sentiment. With public sentiment behind it any re-

1 Some observations on rabies. By E. C. Schroeder. Bureau of Animal [Industry Circu-
Jar 120. 1908.

2Fracts and problems of rabies. By A. M, Stimson. Hygienic Laboratory Bulletin 65,
1910.

THE DOG AS A CARRIER OF PARASITES AND DISEASE. 27

form is possible; without it practically nothing is possible. Undue
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Vv

_ UNITED STATES
DEPARTMENT or AGRICULTURE

DEPARTMENT CIRCULAR 338

Issued May 1925
Washington, D.C. ; é Revised June 1934

PARASITES AND PARASITIC
DISEASES OF DOGS’

By Mavrice C. Hatt, chief, Emmett W. Price, parasitologist, and WILLARD
H..Wricut, associate veterinarian; Zoological Division, Bureau of Animal
Industry * i pas : ‘

CONTENTS
.

‘ Page 25 > Page
Importance of parasite control. ..-.--.-.-.--- 1 |, ‘Internal parasites and diseases due to them... 17
External parasites and parasitic skin diseases - 3] Roundworm infestation. ---------------- 18
= ange. - ; a 3 |... »Hookworm infestation (kennel anemia)-- _ 20
Chigger infestation - iu Whipworm infestation_-..---.--------.-- 24
Tick infestation __ 11 " Heart-worm infestation. 25
Louse infestation._- 13 | . Tapeworm infestation -- 27
Flea infestation.--.--...--------------2-- 15 Fluke infestation -- -- 31
. Tongueworm infestatio 32
Coccidiosis.-._..-------- 33
Canine piroplasmosis..------.----.----- 34

IMPORTANCE OF PARASITE CONTROL

The parasitic diseases.of dogs and cats rank in importance with the
bacterial diseases affecting these animals. No such provisions exist
for collecting statistics on diseases of animals as there are for collect-
ing statistics on diseases of man, so it is not possible to make such
close approximations as to prevalence of disease in veterinary medi-
cine as in human medicine. But conceding first place to distemper,
that almost universal scourge of dogs with its mortality commonly
estimated by veterinarians at about 50 percent, the various forms of
mange are probably entitled to a second position, with a group of
worm infestations following in importance. Worm infestations,
especially roundworm and hookworm infestations, are especially pre-
valent and deadly in puppyhood and most so in tropical and subtrop-
ical countries, although by no means unimportant in temperate
zones. There are a large number of worm parasites and of external
parasites, such as insects and ticks, reported from dogs and cats, but

only a few of the more important ones are considered here.

The importance of these parasites, especially those of dogs, is
heightened by the fact that a number of them are transmissible in
some form to man and to livestock. A number which occur as
adults in the digestive tract of the dog also occur in the same form
and in the same place in man. In addition dogs have a number of
adult parasites which occur as larval or immature parasites in man

! This circular, as revised, includes information on parasites affecting cats,
39851°—-34——1

2 CIRCULAR 338, U.S. DEPT. OF AGRICULTURE

and livestock, including the deadly hydatid with a mortality of about
50 percent for human patients in cases not operated on, various other
tapeworms which have their larvae (bladderworms) in cattle, sheep,
goats, swine, reindeer, etc., and tongueworm, with both adult and larval
stages occurring in man and livestock. Finally, dogs carry such para-
sites as fleas, which attack both man and dogs, and transmit sarcoptic
mange to other dogs and-to man. In many cases the annoying
prevalence ‘of fleas in houses is directly due to flea-infested dogs.

The control of parasites in the dog is therefore necessary and
desirable not only for the sake of the dog but for the sake of human
health and the welfare of the livestock industry. This control is of
two sorts. One method of control is that of prophylaxis or preven-
tion of parasitic infestation and disease, and the other is that of
medicinal treatment where parasitism is actually present in the
absence of preventive measures or in spite of them.

Prevention is the business and duty of the dog owner. It is largely

‘a matter of sanitation and careful supervision of the dog’s habits,
especially his food habits. Dogs usually become infested with para-
sites in one of two ways:

(1) By being in contact with infested premises or infested ani-
mals. Dogs transmit their fleas and lice to one another and trans-
mit their fleas to man and also infect the premises with flea eggs and
larvae, thus giving rise to adult fleas which attack the first human or
canine victim that comes in reach. Worm eggs pass in the feces
(excrement) of the dog and develop to the stage where the eggs or
the larval worms hatching from them will infect dogs or persons,
infection sometimes taking place as a result of swallowing the eggs
or larval worms in contaminated food or water, and sometimes as a
result of the larval worms burrowing through the skin when it is in
contact with contaminated soil.

(2) Dogs become infested with parasites by eating raw or insuffi-
ciently cooked meat, neglected carcasses, discarded viscera, or raw
fish containing the larvae of worms. Such larval worms include the
bladderworms occurring in the viscera of cattle, sheep, goats, swine,
and rabbits. It is the duty of the owner to see that premises are kept
clean, that the excrement is removed frequently and thoroughly,
that dogs eat only suitable and safe food, and that dogs are bathed
and kept clean and free from vermin of all sorts. This involves
supervision of the dog’s habits to the extent of not allowing the
animal to run at large under conditions that permit it to eat what-
ever carcasses it may find or whatever animals it may kill. The dog
that eats offal at the country slaughterhouse or kills and eats rabbits
is practically certain to become infested with tapeworms. Slaughter-.
house offal is probably the most important source of infestation of
dogs with hydatid tapeworm, a menace alike to the owner of the dog,
his family, and his livestock. The neglected dog running at large
collects fleas and lice and contracts mange to an extent not possible
to the dog that is properly cared for and supervised.

Medicinal treatment is the business of the veterinarian, not of the
dog or cat owner. It involves an accurate diagnosis, a matter that
calls for special training, medical skill, and adequate experience, things

_which the dog or cat owner is not likely to possess. Errors in diag-
nosis mean misdirected efforts, with the possibility of injury to the
sick animal, loss of time and money, and the possibility that this lost

PARASITES AND PARASITIC DISEASES OF DOGS 3

time will allow the real condition to go unrecognized until it is too
late to save the animal. Treatment also involves the use of highly
potent drugs, carefully selected with due regard to the end to be

accomplished, and administered in such doses and in such a way as to:

cure disease without injuring the patient. The possible contraindica-
tions for treatment, conditions which make it evident that certain
drugs or doses are dangerous, must be ascertained and kept in mind.
The anthelmintics (drugs used to remove worms) are always poison-
ous, being intended to poison the worms, and must be given in such
doses as will accomplish that object without materially injuring the
patient. Insecticides injudiciously applied to the skin to kill parasites
may injure the skin or kill the patient. In this discussion of parasites
a number of treatments are described, since it may be necessary for an
owner to treat his dogs or cats, when the services of a competent
veterinarian are not available. It is understood, of course, that an
owner gives such treatment at his own risk and that he assumes the
responsibility for his diagnosis, selection of drugs, dosage, method of
administration and technic, and the risk of possible bad results.
Each animal presents his own special individual case, and no general
directions can cover all of the possibilities. Passing judgment on the
individual case is precisely where the skilled veterinarian becomes
indispensable, and whenever possible he should be employed.

EXTERNAL PARASITES AND PARASITIC SKIN DISEASES
MANGE ;

The dog suffers from mange of three sorts—sarcoptic mange, ear
mange, and demodectic mange, whereas cats usually are affected only
by the sarcoptic type. Sarcoptic mange in dogs occurs over the body
and is characterized by the formation of crusts or scabs in advanced
stages of the disease; this form of mange in cats is usually restricted to
the head and neck. Ear mange, as the name implies, occurs in the

ears. Demodectic mange, also called red mange or follicular mange,

occurs over the body and is characterized by a falling out of the hair
and frequently a reddening of the skin in the early stages, the condi-
tion commonly progressing to the formation of pustules. In this
disease and in sarcoptic mange there is a characteristic unpleasant

“‘mousy”’ odor. -
CANINE SARCOPTIC MANGE

Cause.—Canine sarcoptic mange is due to the canine sarcoptic
mange mite, Sarcoptes scabiei canis, a form related to the spiders.
This mite is very small, the largest specimen being less than one-
fiftieth inch long. The general appearance under the microscope is
that shown in figure 1. The sarcoptic mites, this form and its near
relatives, have very short hind legs, not projecting beyond the margin
of the body. When a dog is suspected of having mange, a portion of
the diseased skin should be scraped with a dull knife and the scraping
examined for mites. The scraping must be deep enough to draw
blood, as these mites burrow deep into the skin, and it.may be neces-
sary to make scrapings from several areas. The scrapings should be
softened by soaking in a solution of caustic soda or caustic potash for

half an hour or more, the strong solutions acting more rapidly than -

weak ones, and then placed on a glass slide under a cover glass and

o

4 CIRCULAR 338, U.S. DEPT. OF AGRICULTURE

examined with the low powers of the microscope. Whenever possible
this examination should be made by a competent veterinarian or
zoologist, as these mites are frequently difficult to detect. The
finding of the mites is sufficient to confirm the diagnosis of mange,
but failure to find mites, while it establishes a presumption that the
disease is not mange, does not prove the case, as the mites may be
overlooked or not reached by the scraping.
Symptoms.—Sarcoptic mange affects dogs of all ages and all breeds.
It usually begins about the head and may spread over the entire body
in the course of a month. It appears first in the form of red points
which soon become papules or vesicles, most easily seen where the skin
is thin and without pigment, as on the abdomen. As the mite bur-
rows into the skin it causes irritation and there is an exudate of
serum. As this constant flow
of serum dries it forms the char-
acteristic scab. Simultaneously
this irritation gives rise to itch-
ing, which becomes intense in
the presence of heat or after ex-
ercise, and the animal scratches
and rubs the affected portions
of the body. In doing so it
rubs off the scabs and opens up
sores. Bacterial infection of
these areas may add to the in-
flammation and injury resulting
from the presence of the mite
and the scratching. The hair
also may become matted and
fall out. There is evidently
more or less toxic absorption
from: the mites or from the dis-
_eased skin, as shown by a blood
reaction in the form of an eosino-
philia, a condition frequently
t associated with parasitism, and
FiGurE 1.—The canine sarcoptic mange mite, Sarcoptes the presence of the toxins and
on TUpica® afer Dumretsiber, (ilieroa eee the loss of nervous energy due
seo Mele, 0.4 done es Moe wig; to constant, itching and irrita-
tion cause the animal to become
weak and thin. The skin may show large sores, and the mangy
or ‘‘mousy”’ odor becomes very pronounced. A general impairment
of digestion and other body activities follows and if the disease goes
unchecked the animal dies, usually in 2 or 3 months under conditions
favorable to the disease. The term ‘‘mangy dog” as an expression
of reproach shows the general appreciation of the extremely pitiable
condition and apparent worthlessness of such an animal.
Treatment.--A great aid in the treatment of mange is the use of
such measures as will build up the general health and resistance of
the animal. The dog should receive plenty of good nourishing food,
including a supply of meat suited to the animal’s condition and the
amount of exercise it can take. Exercise and fresh air are important.
Delafond and Bourguinon have recorded the cure of sarcoptic Mange
in the dog by suitable diet, exercise, fresh air, and hygienic measures,

PARASITES AND PARASITIC DISEASES OF DOGS 5

even in an advanced stage of the disease. It is well known that
susceptibility to mange and scabies in various animals depends in
ee on the general condition of the animal and on weather conditions.
Aange in horses and scabies in cattle are much more prevalent in
winter than in summer and more so among animals poorly fed and
cared for than among animals well fed and cared for. On the other
hand, it is reported that dogs in Greenland suffer from mange in the
summer, the disease becoming latent or cured in winter.

In addition to hygienic measures, various treatments may be used
to destroy the mange mites and cure the disease. Among the many
ee which have been used and recommended, a few are noted

ere. o.

The hair over the diseased portions of the body should be clipped,
and it is usually advisable to clip it over the entire body. The hair
may cover up evidence of areas in early stages of mange, from which
areas the disease may spread after apparent cure of evidently dis-
eased areas, and the removal of the hair simplifies treatment and
makes it possible to use smaller amounts of medicinal substances
effectively. The crusts present may be rubbed with green soap to
soften them and an hour or two later the soap and crusts removed.
with a brush and warm water. The next day the application of
substances intended to destroy the mites is begun by treating one
fourth of the body, a different quarter being treated each successive
day, so that the entire body is treated in the course of 4 days. The
applications to each quarter are rubbed in thoroughly, left on for
about 4 days, and then removed with warm water and soap. After
each course of treatment the applications are omitted for 3 or 4 days
and then repeated until the skin is healed and the itching and irri-
tation have disappeared. One application that may be used consists
of 1 part each of oil of tar and green soap in 1 to 5 parts of alcohol.
Another is 1 part each by volume of oil of tar and crude petroleum
oil, and 6 parts of liquid petrolatum. Another is cresol liniment, con-
sisting of 2 parts aqua cresolis and 1 part each of soft soap and alcohol.
Another is sublimed sulphur 2 parts, oil of tar 1 part, potassium
carbonate 1 part, and lard 8 parts. Another is an ointment, consisting
of sublimed sulphur 150 grams, potassium carbonate 8 grams, and
lard 60 grams. Another is flowers of sulphur 1 part, tincture of iodine
1 part, oil of tar 8 parts, and olive oil 8 parts. Ordinary sulphur
ointment, 1 part sulphur to 8 parts lard, may be used: to this may be
‘added 1 dram of balsam of Peru. The ordinary lime-sulphur dips
may be used. The animals should be prevented from licking the
applications, by the use of a muzzle, broad collar, or some other
means.

During the period of treatment the bowels must be kept open by
the use of castor oil or Glauber’s salt, daily, if necessary. The ani-
mals must be protected from cold. All diseased animals should
be isolated for their own benefit and for the protection of those not
’ diseased. It should also be kept. in mind that sarcoptic mange of
the dog is transmissible. to man and that due precautions should
accordingly be taken in handling mangy animals. The disease is
also transmissible to the horse. Mange is a debilitating disease,
leaving the patient more susceptible to various other diseases, and
mangy animals are poor subjects for treatments to remove worms,
being weakened to the point where they are much more liable to

6 CIRCULAR 338, U.S. DEPT. OF AGRICULTURE

succumb to the toxic effects of such anthelmintics as chenopodium
than are animals without such complications as mange. ;

In connection with treatment, one must remember that the premises
used by mangy dogs are infected and that disinfection is therefore
necessary. So far as possible, litter of all sorts should be burned.
Kennels and other constructions should be thoroughly cleaned and
then disinfected with hot, strong coal-tar disinfectants.

FELINE SARCOPTIC OR NOTOEDRIC MANGE

Cause.—Sarcoptic or notoedric mange in cats is due to the presence
of a mite, Notoedres cati, which is smaller than the sarcoptic mite of
dogs; it may be distinguished on microscopic examination from the
sarcoptic mite of the dog by reference to figure 2. This form of
mange is transmissible to dogs, and this possibility
should be kept in mind where dogs and cats are
associated. This type of mange is also communi-
cable to man.

Symptoms.—The mites usually attack the skin
of the neck, ears, and face, and in severe cases the
entire head and neck may be affected. The initial
lesion is in the form of a small vesicle which is
about the size of a pinhead. The vesicles later
become confluent and crusts are formed. The hair

FiGuRE 2.—The feline sar-

coptic mange mite, No-
toedres cati. _ Female.
Dorsal view. Enlarged.
From Gedoelst, 1922,
after Mégnir. (Micron
measurements: Male,
145 to 150 long by 120 to
125 wide; female, 245 to

becomes matted and may fall out. Itching varies
in intensity in individual animals. As the disease
progresses the animal presents a dejected appear-
ance, and death may occur in from 4 to 6 months.
In dogs this type of mange is confined usually to
the head.

280 long by 165 to 175
wide.) |

Treatment.—Coal-tar preparations and other
preparations containing phenol should not be used
in the treatment of mange in cats, as cats are particularly susceptible
to poisoning with such compounds. An ointment composed of 1 part
sulphur to 8 parts lard or equal parts of olive oil or cottonseed oil has
been found effective in many cases. Helmerich’s ointment, composed
of sublimed sulphur 150 grams, potassium carbonate 8 grams, and lard
60 grams, has been recommended. A mixture of balsam of Peru 1 dram,
and sulphur ointment 1 ounce, may be used but care should be taken
not to apply this preparation over too extensive an area of the skin, .
as poisoning may result. As in the case of dogs, the hair should be
slipped over the affected. areas and the scales softened with green
coap before the application of mange remedies.

EAR MANGE

_Cause.—EHar mange is due to a mite, Otodectes cynotis, which is
slightly larger than the canine sarcoptic mite. Owing to their size
‘and the fact that they do not burrow, it is often possible to see these
mites (fig. 3) with the naked eye, either in the ear or in detritus
removed from the ear, the mites appearing as small white objects
moving slowly about.

PARASITES AND PARASITIC DISEASES OF DOGS 7

Symptoms.—These mites puncture the tissues forming the external
canal of the ear and feed on the serum, causing an irritation which,
among other things, interferes with the normal production and dis-
posal of earwax. Asa result the ear canal may
become filled with detritus, consisting of more
or less modified earwax and inflammatory prod-
ucts in the form of scales or powder. The mites
appear to begin operations in the region of the
eardrum, but as they multiply the canal be-
comes more or less filled with the mites, frass,
wax, and scales. The mites alone cause a mild
irritation and a pronounced itching, but the
itching causes the dog to scratch and rub its
ears and shake its head, and these activities on
the part of the dog give rise to scratches, sores,
and bleeding. Affected dogs frequently whine
or howl, and in severe cases may show epilepti-
form spasms, travel in a circle, or show other
evidences of nervous disturbances. More or
less deafness may follow from the plugging of,
the ears and from injuries to them. Bacterial
complications may follow, and inflammation of
the middle and the inner ear and even of the
brain is said to occur in rare instances. The
condition may be diagnosed by carefully removing
some of the material from the ears and finding mites
in it by examination with the naked eye, a hand lens,
or a microscope, or in earlier stages by recovering
these mites by carefully swabbing the region of the
eardrum with a pledget of cotton moistened with a
bland oil, or by examining the ears with a speculum
or otoscope in a good light with suitable illumination.

Treatment.—Treatment for ear mange is not espe-
cially difficult. If the ear is full of detritus, this should
be removed with forceps or a swab, taking care not
to injure the eardrum. The ear canal can then be
liberally swabbed with a cotton pledget soaked in one
of the following preparations: 1 percent carbolic acid
or creosote in glycerin; 5 percent carbolic acid in olive
oil or castor oil; 1 part carbon tetrachloride and 3 parts
castor oil; or 1 part chloroform in 9 parts olive oil or
castor oil. Repeat treatment daily until the animal
is cured.

FIGURE 3.—The ear mite, Oto-
dectes _ cynotis. Female.
Ventral view. Enlarged-
From Banks, 1915. _(Mi-
cron measurements: Male,
350 to 380 long by 250 to 280
wide; female 340 to 530 long
by 210 to 350 wide.)

DEMODECTIC MANGE
Figure 4.—The de-

Tipaentle anes Cause.—The mites, Demodex canis (synonym, D.
ns. Female. folliculorum var. canis), responsible for demodectic
roe be pea mange, differ materially in form from those already
Hirst, 1919. (Mi- described, being elongated, vermiform objects (fig. 4).

cron measure-
ments: Male, 220 to
250 long by 45 wide;
female, 180 to 300
long by 45 to 45
wide.)

must be deep enough to draw blood,

hair follicles.

They are very small and can be detected only by the
aid of the microscope. The diagnosis of demodectic
mange (follicular mange or red mange) may be made
by finding the mites in scrapings. The scrapings
as the mites live down in the

The scrapings may be macerated in caustic and

8 CIRCULAR 338, U. 8. DEPT, OF AGRICULTURE

examined, the procedure being as given for the diagnosis of sarcoptic
mange.

Symptoms.—Demodectic mange may occur in dogs of all ages and
breeds but appears to be more common in young animals and short-
haired breeds. ‘The first evidence of demodectic mange, as a rule,
consists in the appearance of hairless spots, often somewhat red-
dened, these spots commonly occurring about the eyes or at the
elbows and hocks, though they may appear first in other places.
There is very little itching at this time, and though itching may be
more evident later there is usually less of it than in cases of sarcoptic
mange, and when present it is usually intermittent. As the disease
progresses the hairless areas become more extensive and redder,

FIGURE 5.—Dog with demodectic mange, depilatory f

though later the skin may be lead gray in color. This is the so-
called depilatory stage of the disease (fig. 5). At this stage the
mites are aneragane in the hair follicles, and the visible skin changes
are evidences of inflammatory conditions about the follicles and their
sebateone glands. As many as 200 mites may occur in a single hair
ollicle.

Usually the depilatory form of demodectic mange, due to the
uncomplicated cases of mite infestation as described above, becomes
complicated in time through the invasion of the weakened and dis-
eased skin by pus-forming bacteria, and sometimes these complica-
tions appear to be present from the onset of the disease. This con-
dition is the pustular stage of the disease (fig. 6) and in this stage
the previously hairless and reddened areas now show numerous pus-
tules. In and under the skin there are numerous abscesses or pus

PARASITES AND PARASITIC DISEASES OF DOGS 9

pockets, local destruction of the true skin or dermis takes place,
and, according to some investigators, some mites now wander out
of the hair follicles and may even enter the subcutaneous tissues.
The numerous pustules run together and the skin becomes thickened
and so seriously weakened from disease that it is highly susceptible
to injury from rubbing or contact with various objects. The odor
is very unpleasant. There is little or no itching in this stage. The
absorption of toxic products from bacteria and diseased skin tissue
serves to poison the entire system ; bacteria may enter the blood stream,
causing generalized infection; the bodily functions are deranged; the
animal becomes emaciated and weak, and unless the disease is checked
the dog dies in a very pitiable condition.

The disease usually runs a very slow course, commonly for months,
and sometimes up to 2 years or longer. In rare cases there is sponta-
neous cure. ,

Treatment.—The subject of treatment for demodectic mange is
still a controversial matter. Some competent veterinarians report
a large measure of
success in treating
this disease, but
others find treat-
ment generally un-
satisfactory and
will not undertake
it. In advanced
cases of pustular
mange destruction
of the animals is
commonly recom-
mended. In gen-
eral, the treatment
of such cases is such
a long, costly, and FIGURE 6.—Dog with demodectic mange, pustular form.
tedious affair, and
so often ends in failure to obtain a cure, that the owners of the dogs are
dissatisfied. This is especially true because dogs usually are not
brought in for treatment until the disease reaches the pustular stage.
After a few experiences of this sort the veterinarian prefers to avoid
trouble with his clients and the presence of such unpleasant and unpro-
fitable patients. When the treatment is left to the owner it frequently
happens that he wearies of carrying out the prolonged treatment,
forgets it from time to time or finds it inconvenient to attend to
it, or neglects details and thoroughness. Even if he carries it out
conscientiously, failure to cure is not an uncommon result, as much
depends, apparently, on the condition and resistance of the individual
animal. The senior author cured one case of extensive simple depila-
tory mange in a dog by: the daily application of a mixture of olive
oil 100 cubic centimeters, chloroform 30 cubic centimeters, and thymol
5 grams, but it required 100 treatments. In spite of sentimental
considerations, few dog owners would care to carry out a treatment
of this magnitude, especially in view of the fact that failure would

39851°—34——2

10 CIRCULAR 338, U.S. DEPT. OF AGRICULTURE

follow in some cases. In general, treatment should be begun early.
The disease is more curable in the depilatory and localized cases than
in the pustular and generalized cases. Ae

The animal should be clipped before treatment is begun. Of the
treatments which have been recommended, one which has the merit
of simplicity and safety and is recommended as very effective, con-
sists in the daily application of castor oil to and around the diseased
areas. Whatever is used should be throroughly rubbed into the skin,
not neglecting its application between the toes if needed. Liquid
oil of tar has given good results in some cases and failed in others.
Another treatment consists in the application to one fourth of the
body daily, as directed for sarcoptic mange, of an ointment consist-
ing of liquid phenol 1 part, camphor 2 parts, and white petrolatum 6
parts, the dog being bathed on the fifth day in a 2-percent solution
of sulphurated potassa, and the treatment begun again the following
day and continued as long as necessary. Another treatment which
is variously recommended as a cure for demodectic mange or for
the inflammation of the skin accompanying it, consists in the daily
application of Lassar’s paste, which is salicylic acid 2 parts, starch
24 parts, zinc oxide 24 parts, and white petrolatum 50 parts. Another
treatment consists in the use of a 1- to 5-percent formaldehyde solu-
tion; the dog is dipped in this or liberally sponged with it, the dog’s
eyes being protected, and the animal then coated with sulphur oint-
ment or petrolatum. This treatment is repeated every 3,or 4 days
until 4 or 5 treatments have been given, the ointment being removed
before each formaldehyde bath. One objection to the use of for-
maldehyde is that it is painful, having a sting comparable to that of
the formic acid of an ant bite. A treatment which has been recom-
mended widely consists in the use, once a week, of the following
preparation: Kerosene 8 ounces, raw linseed oil 8 ounces, carbolic acid
1 ounce, oil of tar 1 ounce, and sulphur one-fourth pound; this is
applied with mild rubbing. Good results have been reported in
some cases of demodectic mange following the daily application of
a 1-percent solution of rotenone. The solution is made up by dis-
solving 1 gram of rotenone in 10 cubic centimeters of acetone and
then adding 50 cubic centimeters of alcohol and 40 cubic centimeters
of distilled water. The solution should be shaken before use.

In connection with any medicinal treatment, the supplementary
measures noted under the subject of sarcoptic mange should be used.
In addition, the treatment of the pustular type of demodectic mange
should be begun by opening the pustules with a sharp knife and
squeezing out the pus. Under some conditions it has been recom-
mended that the skin be scarified and treated with tincture of iodine,
but this procedure should be left to the judgment of the veterinarian
and carried out by him. Dogs are fairly susceptible to iodine poison-
ing. The pustular stage of mange is said to be greatly benefited in
some cases by the injection of autogenous bacterins or stock poly-
valent bacterins of streptococcic and staphylococcic bacteria of
strains isolated from cases of demodectic mange, but the use of these
bacterins should be left to the veterinarian. Arsenic, in the form of
Fowler’s solution, and sulphur are sometimes given internally for
their effects on the system. Violet rays and even X-rays have been
used in demodectic mange, and good results reported in some cases.

PARASITES AND PARASITIC DISEASES OF DOGS 11
CHIGGER INFESTATION

Cause-—The common American chigger, Trombicula irritans
(also called harvest mite), is a small, red or orange-yellow mite
(fig. 7) which as a six-legged larva (the adult mite has eight legs)
attacks man and the domesticated animals. It occurs from New York
to central Mexico and from the Atlantic Ocean to the Rocky Moun-
tains. A very closely relates species occurs in the northern and
western part of this country. Chiggers have been thought to burrow
into the skin and die there, but recent investigations indicate that
they do not burrow, but merely attath by the mouth parts, and if
left alone become engorged and fall off. |

Symptoms.—Chiggers cause intense itching and
this results in scratching and rubbing which in turn
often result in the formation of sores with subse-
quent bacterial infection. Hunting dogs are espe-
cially subject to attack, owing to exposure as they
range over chigger-infested territory. The chiggers
attach most often about the head, feet, and belly,
causing scattering eruptions which may contain pus. ~
Chiggers usually attach singly, but a dozen or so
sometimes attach at one point. Under favorable F¢vre,7—The com-

mon. American chig-

conditions they may be seen with a hand lens, but ger, Trombicula
irritans. Enlarged:

as a rule chigger infestation in dogs or cats would rom Ewing and
be suspected from signs of itching coupled with a Bartzell, 1918, after
history of chigger attacks on man at the same time measurements:
and in the same vicinity. ieee Gaolane by foo
Treatment.—Sulphur ointment will destroy chig- [7i2¢,,,Mneonged
gers at the point of attachment and in some cases 320 microns | wide.
appears to have a favorable effect on. infected sores 4H E-Ewing)
due to scratching the places attacked by chiggers.
Alcohol in free and repeated applications is also good. Solutions of
coal-tar creosote dips, in the strengths recommended on the labels for
dipping or washing dogs, may be used. Ammonia, sodium bicarbo-
nate, or dilute tincture of iodine serves to alleviate the itching..
Flowers of sulphur has been found of value in preventing attacks
on man by chiggers, and it is probable that it would be of value in
protecting dogs or cats if dusted into the hair. The coal-tar creosote
dips would doubtless be of value for the same purpose. Such dips
should not be used for cats. Oil of tar or fish oil, applied diluted with
alcohol, would probably be repellent but objectionably messy. The
cultivation of ground and the clearing away of underbrush arid rank

vegetation aid in keeping down chiggers.

TICK INFESTATION

Cause.—Various species of ticks will attack dogs and about 14 spe-
cies have been reported from the dog in North America. The more
important of these in the United States are the American dog tick
or wood tick, Dermacentor variabilis, and the brown dog tick, Rhipi-
cephalus sanguineus; these ticks rarely occur on cats.

12 CIRCULAR 338, U.S. DEPT. OF AGRICULTURE

The American dog tick (fig. 8) usually occurs as an adult tick on
dogs, the earlier stages (those of seed tick and nymph) occurring on
various small mammals. It attaches to various parts of the body, —
but displays a preference for
the ears. When fully en-
gorged with blood the female
tick is almost half an inch
long and of a bluish color,
with a reddish-brown shield
with white markings on the
back near the head. This
species occurs in the eastern
half of the United States, in
Figure 8—The American dog tick or wood tick, parts of the west coast, and

male. Dorsal views. Enlarged. from Banks 1008.” occasionally elsewhere in this

country.

The brown dog tick (fig. 9) occurs on dogs as seed tick, nymph,
and adult. It frequently attaches inside a dog’s ears, sometimes deep
in the ear canal. The young ticks
are likely to be abundant in the A
long hair on the neck, but any stage
may occur on almost any part ot
the body, including the spaces be-
tween the toes. In this country
this tick occurs in the South, being
reported from Texas, Louisiana,
Mississippi, and Florida, but it
may be found farther north, being
reported from Ohio, Pennsylvania,
and New York. | Its occurrence
in these Northern States is due, no
doubt, to the fact that dog owners
have transported ticky dogs, mostly
hunting dogs, from the South to
the Nortbern States. It appears
to have taken up the habit of
living indoors over winter as an
adaptation to cold winters, and
according to F. C. Bishopp, of the
Bureau of Entomology, and reports
from various persons, causes seri-
ous trouble by establishing itself
in kennels and about houses.

Symptoms.— Ticks cause local

irritation at points of attachment, Fours o—The brown dog tick, Rhipicephalus
and dogs commonly bite or scratch —sa”guineus: A, Male; B, unengorged female,

: Enlarged; From McIntosh, 1931.
these places. In heavy infesta- ‘ nese

tions the injury may be serious. In addition to the local injury
there is a loss of nervous energy from irritation. The tick buries

PARASITES AND PARASITIC DISEASES OF DOGS 13

its mouth parts in the dog’s skin and sucks blood, and this loss of
blood, a relatively unimportant matter in a light infestation with
ticks, becomes a serious matter in a heavy infestation. Certain ticks
are capable of causing a rapidly fatal paralysis, and cases of the sort
have been reported in dogs. Other ticks carry diseases from one
animal to another, as in the case of the cattle-fever tick, which carries
tick fever of cattle in the Southern States. The brown dog tick of
this country carries a disease—canine piroplasmosis—which is very
similar. to tick fever. The American dog tick has been shown to
transmit the eastern form of Rocky Mountain spotted fever of man.

Treatment.—The simplest control measure and one which is usually
applicable consists in the removal of the ticks by means of the fingers
or with forceps. Occasionally the mouth parts of the tick will be left
in the skin and may form festering sores, but this'does not occur
very often. The control of ticks by hand picking is a time-consuming
process, however. For tnis reason, considerable search has been made
for an insecticide which would be effective for the destruction of the
parasites and yet safe for the host. It has been reported that an
extract of pyrethrum flowers containing a uniform and definite per-
centage of active ingredients is effective for the destruction of the
brown dog tick. Such preparations are marketed under proprietary
names. A stock solution is made by mixing 1 part of the pyrethrum
extract with 3 parts of a solution of 1% pounds of green soap dissolved
in one-half gallon of water. To this combined solution is added water
sufficient to make a dilution of 1 part pyrethrum extract in 19 parts
of the soap-and-water solution. The solution is applied by means
of a sponge until tae coat of the animal is thoroughly saturated with
the liquid. This preparation is said to kill larval ticks almost imme-
diately. It is reported that engorged females live for a day or more
after treatment, but finally succumb.

A 5- to 7-percent solution of pine-oil disinfectant has been recom-
mended for the destruction of the brown dog tick. The use twice
weekly of a powder containing 3 percent of rotenone is reported to be
effective for the destruction of these ticks. The use of drugs or
chemicals for the destruction of ticks on cats is not recommended.
Where animals are exposed to reinfestation, the use of any treatment
can only be palliative. Effort should be made to rid premises of
ticks in various stages of development by spraying kennels and runs
with a hot coal-tar creosote solution or with a pyrethrum emulsion.
As the brown dog tick can live for months under favorable conditions
without feeding, this is a control measure of ora importance. ;

Whenever possible, dogs and cats should be kept out of tick
infested woods and out of contact with tick-infested stray dogs.

LOUSE INFESTATION

Cause—The dog is commonly infested with two species of lice.
One of these is a sucking louse, the sort commonly present on mam-
mals, and the other a biting louse related to the bird lice.

14 CIRCULAR 338, U.S. DEPT, OF AGRICULTURE

The sucking louse, Linognathus piliferus (synonym, Haematopinus
ptliferus), is pale yellow, less than one twelfth of an inch long, and has
a long, slender head (fig. 10), very different from the wide, blunt
head of the biting louse. It may appear blue after feeding on blood.

The biting louse, Trichodectes latus (synonym, T. canis), is clear
yellow in color, with darker markings, smaller than the sucking louse,
and has a short, wide, blunt head (fig. 11).

Cats are susceptible to attacks by the louse, Trichodectes subros-
tratus, which is about the size of T. latus of the dog, but has a more
pointed head. This is the only louse infesting cats; it is not common.

; Symptoms.—The sucking lice feed of se-
rum and blood, and the biting lice feed on
the scales, scurf, and superficial portions of the
skin. In either case they cause irritation,
which may be excessive in heavy infestations.
The itching due to their bites causes the in-
fested animal to scratch and rub, sometimes
causing sores in this manner, and constitutes
a drain on the nervous energy. lLong-haired
dogs appear to be more susceptible to louse
infestation than short-haired dogs, and pups
and very old dogs are. more susceptible to infestation and suffer
more from it than dogs of about mature age. The biting louse
shares with the flea the role of intermediate host of the common
double-pored tapeworm (p. 28), the louse becoming infested with the
intermediate stage of the tapeworm as a result of swallowing tape-
worm eggs as it feeds on the contaminated skin of the dog, and the
dog becoming infested with the tapeworm by swallowing such infested
lice. The tapeworm sometimes occurs in man, especially children,
infection occurring in the same manner as in the dog.

Treatment.—Lice may be destroyed by dipping the dog two or,
preferably, three times at intervals of from 8 to 10 days in one of the
coal-tar creosote dips, diluted as stated on the label
for use on dogs. Repetition at a suitable interval is
necessary, as these dips do not destroy the eggs, and
the lice hatching from them must be destroyed before
they in turn can lay more eggs. Clipping is an aid in

FIGuRE 10.—The sucking louse of
dogs, Linognathus piliferus. Fe-
male. Ventral view. Enlarged.
From Neveu-Lemaire, 1912.
(Measurements: Male, 1.5 milli-
meters long; female, 2 millime-
ters long.)

treatment, as it removes many of the eggs which are
attached to the hairs and permits better contact and
penetration by the insecticide. The hair clippings
should be burned to destroy the lice and their eggs
(nits). Oils, such as castor oil, cottonseed oil, or olive
oil, may be used to destroy lice, the oil being left on
for several hours and then washed off with warm
water and soap. After being oiled, a dog should be
kept in a clean box to keep him from rolling in dirt.

Figure 11.—The
biting louse of
dogs, Trichodectes
latus. Female.
Ventral. view.
Enlarged. From
Neveu - Lemaire,
1912, (Measure-
ments: Male, 1.4
millimeters long;
female, 1.5 milli-
meters long.)

A thick lather of whale-oil or fish-oil ee or an emulsion of 8 parts

of the soap to 1 part kerosene may be use

but kerosene must be used

with caution, the emulsion well made, and the animal not allowed in
the bright sunlight for several hours after treatment. When weather
conditions do not permit dipping or clipping, or when clipping is
undesirable, palliative measures, not very effective in eradicating
lice, may be used. Such measures consist in dusting the hair
thoroughly with pyrethrum powder (buhach or ordinary Persian,

PARASITES AND PARASITIC DISEASES OF DOGS 15

Dalmatian, Caucasian, or Oriental insect powder), allowing it to
remain on for half an hour or so, and then combing or brushing it
out, with the dead and stupefied lice, on to a newspaper, the paper,
lice, and powder then being burned. This treatment must be re-
peated a number of times in order to ‘keep down the lice. Other
powders, containing such insecticides as naphthalene, sulphur, and
tobacco, may be used in the same way.

Experiments indicate that derris powder, when fresh, is effective
for the destruction of lice on dogs and cats. It is used in the pro-

urtion of 1 part of derris to 2 parts of flour or corn starch, the mixture
veing thoroughly dusted into the hair. Pyrethrum powder also ma
be used for the destruction of lice on cats. As previously stated,
coal-tar creosote preparations or other preparations containing pheno!
should not be ‘ed on cats. .

When only biting lice are present they may be destroyed by dusting —
sodium fluoride into the hair and leaving it on, the animal not being
washed for the next ;

10 days. One appli-
cation will usually
destroy all the lice.
The animal should be
prevented from lick-
ing itself, as 1 gram
(about one-fourth tea-
spoon) of sodium flu-
oride will kill a dog of
average size. This
chemical is not of -
value against sucking
lice.

FLEA INFESTATION

Cause.—In the
United States there
ae a fae ae Ficure 12. Tee Hae ee vata lemma Lateral
terest as parasites of dogs and cats. These include two very similar
species, called respectively the dog flea, Ctenocephalus canis, and the
cat: flea, C. felis, the other two being the common human flea, Pulez .
irritans, and the sticktight or chicken flea, Hchidnophaga gallinacea.

The dog flea (fig. 12) appears to be the most common flea attack-
ing dogs and people in the eastern portion of the United States.
It moves about on the host animal between feeds, transfers readily
from dog to dog and from dog to man, but is disposed to remain
. on some host animal rather than off. The eggs laid by the flea fall
off the host animal and in the course of time hatch, giving rise to
elongate larvae which feed on the animal and vegetable content of
the trash present in the dog’s bedding or in other places frequented
by dogs. In time the larva forms a sort of cocoon, and after a period
in the pupal stage the insect emerges as an adult flea. In the house
the development from egg to adult commonly takes place in carpets
and rugs, and in the trash in cellars and basements. The closely
related cat flea has a similar habit and life history.

16 CIRCULAR 338, U. 8. DEPT. OF AGRICULTURE

The human flea (fig. 13) appears to be the most common flea
attacking dogs and persons along the western coast of the United States

FicurE 13.—The human flea, Pulex :rritans.

but remains firmly attached to the skin most of the time.

Male. Lateral view.
Enlarged. From Bishopp, 1921.

and in parts of
the South. It
has substantially
the same habits
as have the dog
and cat fleas, but
spends more time
off its host ani-
mal than do these
fleas.

The sticktight
flea (fig. 14) is
most common in
the Southern
and Southwest-
ern States, but
may occur as far
north as Kansas.
It is normally a
parasite of poul-
try andmay occur
on birds in suffi-
oe cient numbers to
PAN. cause death. It
has little disposi-
tion to move
about on its host,
Dogs

usually become infested with this flea by contact with infested

fowls and premises.
Symptoms.—A number of spe-
cies of fleas, including the dog
fleas, are known to carry the or-
ganism of bubonic plague, a very
serious disease which man shares
with such rodents as rats. This
plague occasionally occurs in the
United States. The human flea
is thought to convey infantile
kala-azar at times. The dog flea,
cat flea, and human flea act as
intermediate hosts of the double-
pored tapeworm, just as the bit-
ing louse has already been shown
to act. In the case of fleas the
larval fleas become infested with
the larval tapeworms ‘by eating
tapeworm eggs present in con-
taminated trash, in bedding, and

Figure 14.-The chicken flea or sticktight flea,
Echidnophaga gallinacea. Female. Lateral view.
Enlarged. From Bishopp, 1921.

elsewhere. Fleas are, therefore, dangerous as carriers of disease and

parasites.

PARASITES AND PARASITIC DISEASES OF DOGS 17

_Aside from their role as carriers, fleas are not only a cause of
discomfort, itching, and irritation to infested dogs and cats, but are
especially annoying in that they readily leave their dog hosts to attack
man. While a few flea bites cause but little annoyance to some
persons, they cause great discomfort to susceptible individuals,
and may produce lesions which are more or less serious and heal
slowly. Numerous and repeated flea bites cause intense itching and
leed to loss of sleep and of nervous energy, a thing which may be
a serious matter in summer, when hot weather makes it difficult

. to sleep even under otherwise favorable conditions.

Treatment.—To be effective any treatment must simultaneously
lead to the destruction of the fleas on the animal and of the eggs,
larvae, and pupae in bedding and elsewhere. The infested dog may
be dipped in a coal-tar creosote solution of suitable strength. If this
is not feasible, pyrethrum powder or powdered naphthalene may be
used in the manner described in connection with dog lice. Derris
powder, as recommended for the destruction of dog and cat lice, is
very effective against fleas on dogs and cats. At the same time the
kennels and runs should be thoroughly cleaned up, all loose trash
burned, and the floors and woodwork scrubbed with a strong, hot
coal-tar creosote stock dip. F.C. Bishopp, of the Bureau of Ento-
mology, states that complete control is usually obtained by means of
one thorough spraying with a good grade of creosote oil containing
between 10 and 16 percent of tar acids. Where sticktight fleas are
present on the premises, the infested fowls should be treated by the
application of carbolated petrolatum to the clusters of fleas, and the
houses, roosts, and other equipment cleaned and disinfected. Where
dwellings are flea infested, liberal and repeated application of pyre-
thrum powder or naphthalene flakes on the floors, rugs, and carpets
will serve to control the trouble if the process is carried out. thoroughly.
In some cases it may be necessary to fumigate with hydrocyanic-
acid gas, a proceeding which should be undertaken only by some com-
petent and responsible person. In many places dogs and cats are
primarily responsible for the presence of fleas in the house and they
should either be kept free from fleas or kept out of the house.

INTERNAL PARASITES AND DISEASES DUE TO THEM

A large number of different kinds of worms have been found in
dogs and cats in various parts of the world, but only a few of the more
important need be discussed here. Some are important because they
are seriously injurious to dogs or cats, and others because they may be
transferred in some stage of their development to man and to live-
stock. Worms are most prevalent in pups and kittens, and are more
injurious to them than to mature animals, many pups and kittens
dying from worm infestations. This high infant mortality, so to
speak, among dogs and cats as well as among human infants, indi-
cates that there is a lack of proper care and of sanitation responsible
for it. The remedy among dogs and cats, as among people, is proper
care and sanitation. The mother should be free from internal and
external parasites before being bred, should then be kept in an area
free from parasitic infestation, and the pup or kitten should be born in
clean surroundings and raised there until it can fend for itself and
until it has acquired some age immunity or resistance to parasitic

39851°—34——3

18 CIRCULAR 338, U. 8. DEPT. OF AGRICULTURE

infection and to the bad effects of infestation. For parasites, as for
other evils, the ounce of prevention is worth the pound of cure. .
When a pup or kitten is infested with worms it it advisable to use
medicinal treatment to remove them, and the more serious the
infestation the more urgent the need of treatment, but the younger
the animal and the more serious the need of treatment the more
dangerous is the treatment. Cats are particularly susceptible to the
unfavorable action of drugs and for this reason it is recommended
that all treatments for worms in these animals be administered by a
veterinarian. . S titers
In treating dogs or cats for worms, it should be kept in mind that

worm remedies (anthelmintics) if potent are also dangerous, and
should be prescribed and administered by a competent veterinarian
whenever possible. Among the conditions which make drug adminis-
tration for worms especially dangerous are ex-
treme youth, age, or weakness of the patient,
or the presence of such debilitating diseases as
mange or such febrile conditions as distemper.
If treatment is imperative under these condi-
tions, diminished doses should be given at 2-
week intervals, removing part of the worms
present each time and thus protecting the pa-
tient. Purgation is highly important in con-
nection with anthelmintics. Adequate doses of
a suitable purgative should be given, as a rule,
with the anthelmintic, and if evacuation of the
bowels does not occur in the course of 3 or 4
hours, another dose of purgative should be
given. Enemas may also be given if it seems
advisable.

ROUNDWORM INFESTATION

Cause——There are two species of round-
worms (ascarids) which commonly infest dogs,
vier of dese peote and both of these occur in the United States.
leonina. Left, male; right, They look very much alike and for practical
Neveu-Lemuire, 1s3, -'°" purposes-need not be definitely identified. One
of these, Toxascaris leonina, is a milky white
worm (fig. 15) which may attain a thickness of about one-twelfth
inch (2 millimeters); the male is 1.6 to 2.4 inches (5 to 6 centi-
meters) long, and the female is 2.4 to 5 inches (6 to 10 centi-
meters) or even 5.4 inches (13 centimeters) long. The internal
genital tubes, which can be seen through the body wall, do not
extend in the female into the anterior third of the body. This is the
worm most likely to be present in mature dogs. The other ascarid,
Toxocara canis, is pale butter yellow in color, of about the same thick-
ness as the preceding, but usually longer; the male is 2 to 4 inches
(5 to 10 centimeters) long, and the female is 2.4 to 7.2 inches (6 to 18
centimeters) or even 8.4 inches (21 centimeters) long. The internal
genital tubes extend in the female into the anterior third, and com-
monly into the anterior ninth, of the body. This is the worm most
likely to be present in pups. ;
Cats, especially kittens, are sometimes infested with roundworms.
Two species may be encountered, one being Toxascaris leonina and

PARASITES AND PARASITIC DISEASES OF DOGS 19

the other Toxocara cati. The latter species is the more common and
is very similar in appearance to T. canis. te
The female worms produce numerous eggs (fig. 16) which pass out
in the feces and develop under favorable conditions of warmth and
moisture, in the course of 2 or 3 days under very favorable condi-
tions, to the stage where each egg contains an infective embryo worm.
When such eggs are swallowed by dogs in contaminated food or
water or in other ways, the eggs hatch and the young worms enter
the walls of the digestive tract, get into blood vessels or lymph vessels,
and finally many of them get to the lungs, usually by way of the blood
stream through the liver and heart. In the lungs they leave the blood
and enter the air passages, ascend these air passages to the mouth
and are swallowed. On reaching the intestine they settle down and
grow to mature worms, the females beginning egg production in the
course of a few weeks. Prenatal infection of the pups in the uterus
of the pregnant bitch has been shown to occur with the second of
the ascarids referred to above. : ' }
Symptoms.—These ascarids are especially injurious to pups, and
as many as 2,000 have been
found in one animal. They
cause derangements .of the
appetite and digestion, and —
heavily infested pups become
unthrifty and emaciated and
may die if the condition is not
relieved. When present in
large numbers the worms may
form masses which produce a
stoppage of the bowels, they
may wander into the ducts of
the liver, into the stomach,
causing the animal to vomit
the worms, or may crawl up
the esophagus and enter the moure 16.—Eggs of dog ascarids: a, b, e, Tozascaris —
lungs or nostrils. The young wine fe d, Toxocara canis. Enlarged. From ~
worms leaving the blood and mess i
entering the air passages of the lungs may cause such serious injury
to the y ree as to produce pneumonia and this may terminate in
death.
The presence of these worms may be suspected when pups are
unthrifty and have a history of passing worms or when they are
known to have been associated with older dogs infested with worms.
The symptoms of roundworm infestation in cats are about the same
as those for roundworm infestation in dogs. Bloating and evidence
of acute abdominal pain are the usual symptoms of roundworm infes-
tation in kittens. Diagnosis is best made by a microscopic examina-
tion of the feces and the finding of the eggs (fig. 16). This examina-
tion can bé made by any competent veterinarian. _ ;
Treatment.—The most effective drug for removing ascarids from
dogs is oil of American wormseed (chenopodium). It may be given
in hard or soft gelatin capsules at a dose rate of one-fourth fluid
dram (1 cubic centimeter) for a dog weighing 22 pounds (10 kilo-
grams). This should be immediately preceded or followed by 1

20 CIRCULAR 338, U.S. DEPT. OF AGRICULTURE

fluid ounce of castor oi]. The dog may vomit after treatment, but
experiments on many dogs show that the treatment will remove all
the ascarids present in practically all cases regardless of vomiting.
If the bowels do not move in 4 or 5 hours it is advisable in the case
of sick or weak dogs to give another ounce of castor oil. As already
noted, it is dangerous to give chenopodium to dogs under certain
circumstances, and the services of a veterinarian should be obtained
if possible to prevent accidents. The feces passed for the 2 days
after treatments for worms of any sort should be carefully collected
and burned or buried deep, as they have an unusually high content
of worm eggs. . .

Either carbon tetrachloride or tetrachlorethylene, given in the same
dose and manner as stated for hookworms (p. 23), is also very effective
in removing ascarids from dogs, being only a little less effective than
chenopodium; either is safer than chenopodium. In cases of heavy
ascarid infestation, particularly in puppies, it is advisable to follow
either of the above-mentioned drugs in 5 hours by an adequate dose of
castor oil to prevent clumping of the ascarids in the intestinal tract
with possible obstruction; or a suitable dose of Epsom or Glauber’s
salt may be given immediately following the treatment.

Santonin is effective in removing ascarids from dogs when it is
properly given. It is usually safe and is especially valuable in the
case of animals in which the digestive tract is inflamed. It should
be given in the morning, 3 hours before feeding, every day for 5 or
6 days in doses of one-fourth to 1 grain, according to the size of the
animal, and accompanied by an equal quantity of calomel.

Oil of chenopodium is twice as toxic for cats as for dogs and should
not be used for cats in a dose exceeding 0.05 cubic centimeter for each
2.2 pounds of body weight or 0.25 cubic centimeter for an 11-pound
cat, immediately preceded or followed by a purgative dose of castor
oul. Tetrachlorethylene administered in gelatin capsules in a dose
of one-fourth fluid dram (1 cubic centimeter) for an 11-pound cat,
followed in 5 hours by an adequate dose of castor oil, is a safe and
effective treatment for the removal of ascarids from cats.

Preventive measures are along the line of sanitation and depend
largely on the fact that the infective agents are the worm eggs which
pass in the feces. The prompt and thorough removal of these feces
from yards and kennels removes the source of infection. Dirt
surfaces should be scraped and renewed from time to time, and wooden
and concrete structures cleaned with boiling water, soap, and lye,
or hot, strong coal-tar creosote solutions, dependence for results
being placed primarily on the vigorous and thorough use of a brush.
Especial attention should be paid to keeping pups or kittens in clean
areas away from infected places and from older animals, and to
keeping these older animals free from worms by treatment whenever

necessary.
HOOKWORM INFESTATION (KENNEL ANEMIA)

Cause.—Dogs are frequently infected in this country with the com-
mon dog hookworm, Ancylostoma caninum. This worm (fig. 17) is
comparatively small, the male from a little over one-third to one-half
inch (9 to 12 millimeters) long, and the female from a little over one-
third to almost 1 inch (9 to 21 millimeters) long, and thinner than an
ordinary pin. The mouth is armed with six pointed teeth (fig. 18),

PARASITES AND PARASITIC DISEASES OF DOGS 21

and the worm attaches with this armed mouth to the lining of the
small intestine and sucks blood. Another dog hookworm, the narrow-
headed hookworm, Uncinaria stenocephala, is not uncommon in dogs

FIGURE 17.—A portion of the FIGURE 18.—The common dog hookworm,
“small intestine of a dog; slit Ancylostoma caninum. Head. Dorsal
open to show 6 attached view. Enlarged. From Riley and Fitch,
hookworms. Natural size. 1912, after Looss.

Adapted from Fiebiger, 1923.

in Europe and in foxes in the United States and Canada, but appears
to be very rare in the dog in this country. This is a smaller worm,
the male being one-fifth to one-third inch (5 to 8 millimeters) long,

FIGURE 19.—The narrow-headed dog hookworm, Uncinaria stenocephala. Head. Left, dorsal view;
right, lateral view. Enlarged. From Riley and Fitch, after Looss.

and the female one-third to almost one-half inch (8 to 11 millimeters)
long. The mouth is armed with cutting plates (fig. 19), but is
without ‘the six teeth which are present in the common dog hook-
worm. It is, however, a blood sucker like the other.

22 CIRCULAR 338, U.8. DEPT. OF AGRICULTURE

A third species of hookworm, Ancylostoma braziliense, is sometimes
found in dogs in the Southern States. This worm is about the size of
Uncinaria stenocephala; the mouth is armed with 2 large and 2 small
teeth. All three of these hookworms may occur in cats, the most
common being A. caninum. ’

The female worms produce numerous eggs (fig. 20) which pass
out in the feces and under favorable conditions may develop in the
course of 36 hours to the stage where each egg contains an active
embryo. In the course of from 3 to 6 days, as a rule, a first-stage ©
larva’ hatches from the egg. In about 3 more days this larva molts
its skin and forms a second-stage larva. In about 8 more days
this larva molts to form a third-stage larva which retains the skin
of the previous stage for a time at least. This is the infective larva,
capable of infecting dogs when swallowed in contaminated food
or water, or when put in contact with the feet or any part of the dog’s
skin. Whether the larvae enter by the mouth or through the skin,
they go into the circulation and behave in much the same way that
the ascarid larvae behave, ultimately getting to the lungs, entering the
air passages, going up these to the mouth, being swallowed, and

FiGuRE 20.—Eggs of common dog hookworm. Enlarged. From Railliet, 1893.

finally reaching the small intestine, where they undergo two more
molts and then become mature worms. Eggs from these worms
usually appear in the feces in 4 or 5 weeks after infection takes
place, but have been said to appear as early as 16 days after infection.
In all probability prenatal infection of pups in the uterus of the
mother occurs occasionally, and perhaps frequently.
Symptoms.—Owing to the fact that hookworms are bloodsuckers
and that such worms not only remove blood from an animal but also
appear to produce poisonous substances which exert an injurious ef-
fect on the blood, dogs heavily infested with hookworms usually show
anemia (a condition in which the blood is thinner and paler than nor-
_ mal, which is shown by a pale color of the mucous membrane in the
lining of the mouth and eyelids) and edema (a condition in which
there is an accumulation of serum which seeps from the thinned
blood into the tissues and accumulates in pendant portions of
the body, as under the jaw). The disease is sometimes referred to as
kennel anemia. In early stages of the disease there are digestive
disturbances, and in later stages there is often diarrhea, sometimes
with blood visible in the feces. Owing to the impoverished condi-
tion of the blood and to other disturbances due to the worms, the

PARASITES AND PARASITIC DISEASES OF DOGS 23

infested dogs become weak and emaciated, the resistance to disease
and to unfavorable conditions is diminished, and the vitality is re-
duced. In severe cases the following symptoms may be observed: A
sunken eye, foul breath, unthrifty coat, reddening of the skin inside
the thighs and elbows, pronounced dullness or depression, and a slow
healing of operative wounds or. accidental injuries, with a tendency
to ulcer formation in such cases. The larval worms going through
the lungs have been reported as the cause of a fatal pneumonia in
pups. Pups are highly susceptible to infection with hookworms and
to the bad effects of such infestations and many of them die from
hookworm disease, especially in the South. ,

When the symptoms noted above are present, hookworms may be
suspected as the cause, but it is inadvisable to allow dogs to go to
the stage where they show clinical evidence of hookworm disease, as
such dogs have a diminished resistance to the drugs used in removing
the hookworms. In regions where hookworms are prevalent, espe-
cially in the South but also in many other parts of this country,
the feces of dogs, and especially of pups, should be examined occa-
sionally for worm eggs, and, if they are present, suitable treat-
ment undertaken at once without waiting for ill effects to become
evident.

Hookworm infestation in cats is usually light and is likely to be
overlooked. Heavy infestations, however, would give rise to symp-
toms similar to those described previously for dogs.

The larvae of Ancylostoma braziliense may attack man and give rise
to a progressive type of skin eruption known as “creeping eruption,”’
which is sometimes very difficult to cure.

Treatment.—Carbon tetrachloride in a dose of 0.3 cubic centimeter
per kilogram (2.2 pounds) of body weight, or 3 cubic centimeters for
a 22-pound dog, is an effective drug for the removal of hookworms.
Carbon tetrachloride should not be given to very young dogs or to
those suffering from calcium deficiencies, such as rickets, etc. Tetra-
chlorethylene is an effective drug for the removal of hookworms from
dogs. It should be given in a dose of 0.2 cubic centimeter per kilo-
gram of body weight or 2 cubic centimeters for a 22-pound dog.
Tetrachlorethylene is a much safer drug than is carbon tetrachloride
and should be used in preference to the latter, particularly in the
treatment of animals in poor physical condition, in puppies and young
dogs, and in those suffering from calcium deficiencies.

Either of these drugs may be given in hard or soft gelatin capsules.
Care should be taken to avoid breaking such capsules in the mouth as
inhalation of the above-mentioned drugs may lead to serious reactions.
Animals should be fasted for 12 hours prior to treatment. The com-
mon procedure is to give the usual meal at night, and to administer
the treatment in the morning before feeding. Animals may be fed
3 hours after treatment but in case a purgative such as castor oil is
administered some time after the anthelmintic, food should be with-
held until after its administration. In the ordinary case of hookworm
infestation, a purgative is not necessary in connection with the above-
mentioned drugs, but in cases of concomitant ascarid infestations,
particularly in puppies and young dogs, it is advisable to administer
Epsom salt or Glauber’s salt immediately following the worm medi-
cine or to give an adequate dose of castor oil 5 hours after the adminis-
tration of the worm medicine. Some veterinarians prefer milk of

24 CIRCULAR 338, U. 8. DEPT. OF AGRICULTURE

magnesia as a purgative for puppies and young dogs; this may be
given immediately following carbon tetrachloride or tetrachlorethylene
but an amount sufficient to produce an adequate bowel movement
should be administered. Fats, oils, and cream should be excluded
from the diet for several days prior to the administration of either
carbon tetrachloride or tetrachlorethylene. This applies also in the
case of cats.

Tetrachlorethylene is the drug of choice for the removal of hook-
worms from cats, being much safer for use in cats than is carbon
tetrachloride. The dose rate and the manner of administration are
the same as for dogs. In cases of concomitant ascarid infestations in
cats, a purgative should be given as outlined above. ;

Ordinarily treatments for worms should not be given to pups until
they are weaned, but usually pups 2 weeks old or older may be given
tetrachlorethylene with safety. Animals with severe inflammation
of the digestive tract appear to be bad risks for this treatment as for
most anthelmintic tréatments. In connection with the treatment,
the same preventive measures given for ascarids should be employed.

WHIPWORM INFESTATION

Cause—The whipworm, Trichuris vulpis (synonym, T. depress-
iuscula), is so named because of its resemblance to a tiny whip (fig. 21),
the short, thick posterior portion of the body forming the handle and
the slender, anterior portion, which is about three times as long, form-
ing the lash. It is from 1.8 to 3 inches (4.5 to 7.4 centimeters)
long. The eggs (fig. 22) produced by the female worms are lemon-
shaped, with a knob at each pole. ‘These worms are very common
in dogs in the United States but are not known to occur in cats.

The worm eggs pass in the feces and an embryo develops in each
egg. As a rule this development is slow, usually requiring several

FIGURE 21.—The dog whipworm, Trichuris vulpis. Male. Enlarged. From Fiebiger, 1912.

months. When eggs containing these infective embryo worms are
swallowed by a suitable host the eggs hatch and the young worms
develop for a short time in the snail aneestine and subsequently in
the cecum (the blind gut at the union of the small and large intes-
tines). Here they apparently enter the mucosa by means of a
piercing lancet in the mouth of the young worm. “As the worm
develops, the anterior portion of the body remains sewed into the
mucosa, while the posterior portion hangs free in the lumen of the
cecum. The worms apparently become mature in about 3 months.
In heavy infestations these worms may occur in the colon and rectum
as well as in the cecum.

Symptoms.—These worms not infrequently give rise to a low-
grade inflammation at the point where they attach, and as they are

PARASITES AND PARASITIC DISEASES OF DOGS 25

most commonly present at the tip of the cecum this is the place
where a reddened area is most often seen. The worm’s habit of
sewing into the mucosa opens small wounds which probably afford
entrance for injurious bacteria. A closely related species of worm
im man appears to be responsible for symptoms of distress resembling
a low-grade appendicitis. The exact symptoms produced by these
worms in dogs are as yet matters which require more careful inves-
tigation than they have received. In many cases the worms appear
to do little harm and to cause no visible symptoms.
Treatment.—Whipworms are not very resistant to the drugs which
are injurious to parasitic worms in general, but at the same time the
removal of these worms is somewhat difficult. Apparently the reason
is that it is difficult to get the drugs in contact with the worms. In
their passage through the stomach and small
intestines drugs are greatly diluted with the con-
tents of the digestive tract and are also absorbed
to a greater or less extent. Of the amount of
drug which reaches the ileocolic valve, at the
union of the small and large intestines, only a, cere
little and perhaps none will enter the cecum or el geeeeti, "enlarged.
get to its tip where the worms are usually %iom Riley and Fitch,
situated. Consequently a single dose of a 3
drug is less likely to reach and kill the worms than it is to
miss them. When a number of repeated doses are given, the like-
lihood. of the drug’s reaching the worm is greatly increased. At
present the most satisfactory and feasible treatment consists in the
daily administration of equal amounts of santonin and calomel in
the morning, in doses of one-fourth to 1 grain each, according to
the size of the dog, the treatment being kept up for a week, sus-
pended for a week, and then repeated for a week. In place of using
this routine treatment over a period involving 3 weeks, the treat-
ment may be kept up as long as the whipworm eggs appear in the
feces on microscopic examination, suspended whenever they disap-
pear, and stopped if repeated examinations of the feces show that
eggs are no longer present.

HEART-WORM INFESTATION

Cause.—The heart worm, Dirofilaria immitis, of dogs and, occasion-
ally, of cats occurs in the right ventricle of the heart and in the pul-
monary artery (fig. 23). This worm is long and slender, the male
about 5 to 7 inches (12 to 18 centimeters) long, and the female 10 to
14 inches (25 to 35 centimeters) long. . The eggs hatch in the uterus
of the female worm and the larvae are deposited directly into the blood
stream. The heart worm is commonly encountered in dogs in the
South but apparently this parasite is extending its range to the North.
It is found not only in dogs which have been taken South for hunting
or other purposes, but also in dogs born and raised in the North that
have never been in the South. . .

The life cycle of the worm is complex. The larvae which the female
worm discharges into the blood are abundant in the blood vessels of
the skin, especially at night. Mosquitoes feeding on infested dogs
take these larvae into the digestive tract with the blood, and the
larvae pass through the walls of the mosquito’s stomach and reach the
malpighian tubules where they undergo considerable development.
Later, the young worms pass to the mouth parts of the mesquito,

26 CIRCULAR 338, U.S. DEPT. OF AGRICULTURE

escape by breaking through the walls of the labium while the insect is
feeding, and enter the blood vessels of the skin through the wounds
produced by the bites of the mosquito. The young worms eventually
reach the heart where they become sexually mature in 8 or 9 months.
Short-haired dogs are more susceptible to heart worms than long-
haired. dogs, probably because they have less protection against mos-
quito bites.

Symptoms.—The presence of these worms in the heart may give
rise to a variety of symptoms. In hunting dogs the first symptom
usually noted is that the animal tires easily; the dog may gasp, breathe
heavily and collapse. In cases of long-standing abdominal dropsy,
the edematous swellings of the lower part of the chest and legs are
common symptoms. A cough may be present, and nervous symp-
toms, such as photophobia or fear of light, convulsions, and symptoms
resembling those of rabies or hydrophobia have been reported. Death
may result from asphyxia, embo-
lism, and dilation of the heart.

Diagnosis is made by microscopic
examination of the blood for the
presence of larvae; this can be done
by any competent veterinarian.

Treatment—A drug consisting
of sodium-antimony-III-bis-pyro-
catechin-disulphonate of sodium
has been found of value in the
treatment of dogs infested with
the heart worm. Intramuscular
injections are made daily for 6
days each week, treatment being
omitted eyery seventh day. The
initial daily dose, administered over
the first 6 days, varies from 0.5 to
1.0 cubic centimeter, depending on
the bea panos of the

os is animal. For each succeeding 6-da,

ee nin, period, the daily dose is fearsaee!
ae by 0.5 to 1.0 cubic centimeter, the
maximum daily dose being 3.0 cubic centimeters. In tests in the
Bureau of Animal Industry, the total amount of the drug required to
effect a disappearance of the microfilariae from the peripheral circula-
tion has varied from 21 to 33 cubic centimeters, and the course of
treatment has lasted from 20 to 25 days. Apparently a maximum
concentration of antimony in the system is necessary to effect per-
manent sterilization of the blood stream, and, in general, best results
are secured when treatment is pushed to the limit of tolerance in order
to attain this concentration as rapidly as possible. However, not all
dogs are capable of tolerating a continuous course of injections, and
in some cases it may be necessary to suspend treatment for a period of
several days if unfavorable reactions occur.

Dogs which are in good condition and which do not show marked
symptoms of heart involvement generally tolerate the course of injec-
tions without showing marked unfavorable reactions. Other animals
show mild to severe systemic reactions which consist in rise in tem-
perature and increase in the respiration and pulse rates, In case

PARASITES AND PARASITIC DISEASES OF DOGS ot

these symptoms appear, it is advisable to suspend treatment until the
temperature and pulse rate return to normal.

Heperbuents indicate that some or all the adult worms are killed by
the drug. Treated animals usually show improvement in physical
condition, in heart action, and in working capacity.

The drug may be used intravenously ae. and the period of treat-

ment can be shortened by the use of this method. For a 40-pound
dog, the initial dose is 1.0 cubic centimeter; a dose of 2.0 cubic centi-
meters is given on the third day; on the fifth, seventh, and eighth
days, a dose of 2.5 cubic centimeters; and on the ninth, tenth, and
twelfth days, a dose of 5 cubic centimeters is administered.
_ No standard dose rate for this drug can be prescribed, and emphasis
is placed on the fact that the dose must be judged on the basis of
degree of infestation and the physical condition, as well as the weight,
of the animal. In view of this fact, treatment should be administered
only by a veterinarian. Until experience is gained through the use of
the drug, a low dose rate should be used for the first 2 or 3 injections
in order to establish tolerance of the animal for the drug. In case of
severe reactions following the use of the drug, the administration of a
suitable dose of a 10-percent solution of calcium gluconate has been
found of value.

Prevention consists in keeping dogs from being bitten by mos-
quitoes. Dogs should be kept away from places frequented by
mosquitoes, especially after sundown and in the early morning.
Keeping dogs in enclosures screened to keep out mosquitoes is sound
practice, and in the Fiji Islands mosquito-proof kennels with self-
closing doors have been used.

TAPEWORM INFESTATION

Cause.—Tapeworms are elongated, flat worms made up of few to
numerous segments and, with a head which is usually provided with
4 suckers and 2 or more hook circlets. The head is located at the
small end of the worm. Dogs are infested with a number of kinds of
tapeworms, ranging in size from the small hydatid tapeworm, Echino-
coccus granulosus (synonym, Taenia echinococcus), which is less than
two fifths of an inch (1 centimeter) long, to the marginate tapeworm,
T. hydatigena (synonym, T. marginata), which is from 2.5 to over 16 —
feet (75 centimeters to 5 meters) long, or to the broad fish tapeworm,
Diphyllobothrium latum (synonym, Dibothriocephalus latus); which
may attain a length of almost 30 feet (9 meters). All the dog tape-
worms live in the small intestine of the dog. All of them produce
eggs which pass out in the feces and which on being swallowed by a
suitable host animal will develop to a larval tapeworm, taking the
form of a bladderworm of some sort. The host of this bladderworm
will be in some cases a domesticated animal, such as the sheep, cow,
or pig; in some cases a wild animal, such as the hare or rabbit; in some
cases a fish; and in other cases an insect, such as the dog louse or flea.
In any case the bladderworm will not occur in the lumen of the
digestive tract, but will occur in the tissues, such as the lungs, liver,
muscles, mesenteries, brain, or intermuscular or subcutaneous con-
nective tissue, or in the body cavity. In the larger animals, such as
sheep, cattle, and swine, the bladderworms may be very large, as in
the case of the hydatid, which may attain the size of a child’s head
and which is often the size of an orange; in insects, such as the flea or
louse, the bladderworm is very tiny, as it must be in a host of this size.

5

28 CIRCULAR 338, U.8. DEPT. OF AGRICULTURE

Probably the most common of the tapeworms in the dog is the
common double-pored dog tapeworm, Dipylidium caninum. This

-——4+

j ‘
Aomm. FIGURE 25.—Mature segment ,
FIGURE 24.—The six-crowned double-pored of six-crowned double-pored
tapeworm, Dipylidium — sexcoronatum. tapeworm, Dipylidium __ sex-
Head. Enlarged. From Hall, 1919. coronatum. Enlarged. From

Hall, 1919, after von Rétz,
1900. :

tapeworm and a closely related species, the six-crowned double-pored
tapeworm, D. sexcoronatum, have more than two circlets of hooks on the
head (fig. 24), and have

a genital pore on each Yromin.

side of each segment
(fig. 25); the thin-shelled
eggs occur in egg cap-
sules (fig. 26) and are
often found in these
capsules in the feces.
The segments may be

Figure 26.—The common double-
pored tapeworm, re al
caninum. Egg capsule.

iJ ry
FIGURE 27.—The serrate dog tapeworm, Toenia pisiformis.
En. Head, viewed from the front. Enlarged. From Hall, 1919.

[=
larged. From Stiles, 1903.

white or pink, and the terminal segments break off from time to time
and either escape in the feces or creep out of the anus; such escaping

PARASITES AND PARASITIC DISEASES OF DOGS 29

segments are often seen and referred to as rectal worms or pinworms.
The common double-pored tapeworm has a larval stage in fleas and
the biting lice of dogs. -The fleas become infected while they are flea
larvae feeding on the organic matter in trash, the larval fleas swallow-
ing the tapeworm eggs in this trash. Biting lice swallow the eggs
while feeding on the contaminated skin of the dog. In these insects
the tapeworm eggs hatch and the escaping embryo develops to a
larval tapeworm in the body of the insect. When dogs, annoyed by
the itching and irritation due to these insects, hunt them out and
swallow them, the tapeworm larvae become adult tapeworms in the
intestine of the dog. This tapeworm sometimes occurs in man,
especially in children, as a result of the accidental swallowing of
infested fleas or lice by persons.

A larger group of tapeworms is made up of forms which have only
two circlets of hooks (fig. 27) and have a genital pore on only one side
of each segment (fig. 28). The thick-shelled eggs do not occur in egg
capsules but in a uterus from which some eggs escape into the intesti-
nal contents and feces. The eggs (fig. 29) occur as isolated specimens

eo a

in the feces. The segments, usually containing only a part of the
original egg content, escape in the feces and in time break up, releasing
the remaining eggs, which are washed about on the ground and on
vegetation by the rain. When such eggs are swallowed by suitable
hosts, such as sheep, cattle, swine, hares, rabbits, etc., the hosts varying
with different species of tapeworms, the eggs hatch and each releases
an embryo which penetrates the walls of the digestive tract and
develops in some tissue (liver, lungs, muscles, brain, intermuscular or
subcutaneous connective tissue, etc.) to form a larval tapeworm or
bladderworm (fig. 30). When these bladderworms are eaten by
dogs, the tapeworm head in the bladderworm resists digestion and
becomes the head of a tapeworm in the intestine of the dog.

Other dog tapeworms include such forms as the broad fish tape-
worm, Diphyllobothrium latum, which has 2 slitlike suckers in place
of the 4 rounded suckers of the preceding forms, and which has its
intermediate stages in fish. Dogs become infected by eating infested
fish. The broad fish tapeworm also occurs in man. 2, cvs

Cats may harbor the double-pored dog tapeworms, Dipylidium
caninum and D. sexcoronatum, the broad fish tapeworm, Diphyllo-

30 CIRCULAR 338, U. 8. DEPT. OF AGRICULTURE

bothrium latum, and the cat tapeworm, Taenia taeniaeformis (synonym,
T. crassicollis), the latter species being the most important. Taenia
taeniaeformis is from 6 inches to 2 feet (15 to 60 centimeters) long, the
head is armed with a double circlet of hooks, and the suckers, four in
number, are prominent, pointing forward and outward; there is no
neck, segmentation beginning immediately back of the head, and the
first segments being as broad as the head or
broader. The bladder-worm stage of this tape-
worm occurs in the livers of rats, mice, muskrats,
and other rodents. Cats become infested by eat-
ing the infested livers of these animals.

. Symptoms.— In general, tapeworms in the dog
may cause disturbances in appetite and digestion,
a disposition to vomit, general restlessness, and
FIGURE | 20-7 Hes of sometimes cramps. In heavy infestations they may

worm, Tueniapisifor- cause an inflammation of the digestive tract and

From Railige is, occasionally cause occlusion, or stoppage, of the

intestine by filling and blocking the intestinal
lumen. In addition, tapeworms in heavy or even light infestation
may cause more or less well-marked nervous disturbances, in some
cases simulating rabies. The passage of a segment or a string of
segments through the anus often causes itching or irritation, mani-
fested by the dog’s sitting down and dragging itself forward on
its haunches. This symp- ;

tom is sometimes said to
be due to pinworms in
the dog, but dogs do not
have pinworms. The com-
mon double-pored tapeworm
is especially likely to cause
this symptom, and _ seg-
ments of this worm are
sometimes referred to as
pinworms or rectal worms. '

Cats infested with Taenia
-taentaeformis may show loss
of appetite, transient diar-
rhea followed by constipa-
tion, salivation and, in
some cases, persistent vom- HONS
iting. In kittens the ab- eee he

domen may be distended, Fievre 30—Sheep muscle showing two bladderworms,
the animals exhibiting evi- eae Actual size. From Hall, 1921, after
dences of acute abdominal
pain. Nervous symptoms, such as epileptiform convulsions, have
been reported as symptoms of tapeworm infestation of cats.

Treatment —One of the most effective treatments for the removal
of tapeworms from dogs consists in the administration of arecoline
hydrobromide in doses of one-eighth grain to small dogs, one-fourth
grain to dogs of medium size, and one-half grain to large dogs. The
treatment is given in the morning after food has been withheld over-
night, and no food is given for 3 hours after dosing. No purgative is
given with this drug, as the drug usually is itself a very fast and
effective purgative. The efficacy of arecoline hydrobromide is said to

Ne

PARASITES AND PARASITIC DISEASES OF DOGS 31

be somewhat enhanced by the use of preliminary high colonic irriga-
tions. The drug is quite safe in the majority of cases, but in many
cases the animal will appear depressed and subdued for some time after
treatment. Very weak or sick animals must be given diminished doses
or given some other and safer treatment if treated at all. In any case,
and especially in the case of such sick and weak animals, it is advisable
to call in a veterinarian. Other drugs which may be used are those
such as oleoresin of male fern, kamala, and freshly ground areca nut.

Arecoline hydrobromide may be used for the removal of tapeworms
from, cats, but the drug is more poisonous for cats than it is for dogs.
The dose of the drug is from one twenty-fifth to one-sixteenth grain
for adult cats of average weight; the latter dose should not be
exceeded. Kamala in a dose of 1 gram in hard gelatin capsules for an
average-sized cat is another treatment which is quite effective for the
removal of some species of tapeworms from cats. _As cats are par-
ticularly susceptible to poisoning with tapeworm remedies, it is prefer-
able that such remedies be administered by a veterinarian who 1s best
qualified to judge the proper dose of any such drug.

FLUKE INFESTATION

There have been a number of species of flukes reported from dogs
and cats in various parts of the world. One species, Troglotrema
salmincola, is of special importance, since it is responsible for a fatal
disease of dogs known as salmon poisoning.

Cause—The salmon-poisoning fluke is very small, about one
fiftieth to one twenty fifth of an inch (0.5 to 1 millimeter) long, and
occurs in the small intestine of dogs. Cats may become infested, but
apparently this fluke causes little or no injury to this animal. The
distribution of this fluke in the United States is limited to Oregon,
Washington, and the northern part of California.

The life history of the salmon-poisoning fluke, like that of other
flukes,iscomplex. The egg of the fluke passes out in the feces and after
a period of incubation in water releases a free-swimming larva or mira-
cidium. This larva penetrates into water snails, Goniobasis plicifera
var. silicula, and in the course of time gives rise to other larvae known
as cercariae. These cercariae escape from the snail host and penetrate
into, and become encysted in, the kidneys and flesh of salmonoid
fishes. Dogs and other susceptible animals become infested with the
parasite by eating such infested fish. rate :

Symptoms.—The symptoms of salmon poisoning, which develop
after the ingestion of infested fish, resemble those of distemper.
Recent work by Oregon investigators indicates that the disease is due
to a virus, the fluke acting as a carrier of the virus or as an inoculating
agent. The disease manifests itself by a sudden rise in temperature
about 6 to 8 days after the dog has eaten the infested fish; this rise in
temperature is followed by a loss of appetite and marked depression.
After the second or third day the temperature drops gradually, and
this is followed by a discharge of pus from the eyes and swelling of
the eyelids and face. The animal may vomit persistently. On the
sixth or seventh day diarrhea sets in, the feces being blood tinged at
first and later consisting of almost pure blood. There is a noticeable
loss of weight, the temperature drops to subnormal, and usually the
animal dies. Recovery is rare, but dogs recovering are Immune to

subsequent infection.

32 CIRCULAR 338, U. $8. DEPT. OF AGRICULTURE

Treatment.—There is no satisfactory treatment for salmon poison-
ing; all drugs tried for the removal of the flukes have proved to be
ineffective. It is reported that the disease may be prevented by the
use of apomorphine within a few hours after dogs have eaten para-
sitized fish. The best prevention, of course, is to keep dogs from eating
raw salmon taken in the area in which salmon poisoning occurs.

TONGUEWORM INFESTATION

Cause-—The tongueworm, Linguatula serrata (synonym, L.
rhinaria), is not a true worm, but is a degenerate relative of the
spiders, ticks, etc. It lives as an adult in the nostrils of the dog and
some other animals,
and in this stage it
is a wormlike
animal with exter-
nalringlike segmen-
tation (fig. 31).

This parasite does

apres D aN aa hae Son <a

a male is about four-

——————— os Hy fifths inch (18 to 20

FIGuRE 31.—The tongueworm, Linguatula serrata. Upper figure, entire millimeter SS) long,
ene gone foes figure, cre owes Ed ee and the female 1s
Sromtbne mien. Weer uterovagina (dotted) and intestine. larged. about 3 to 4 inches

- - (Sto 10 centimeters)
long. The eggs (fig. 32) from the female worms in the nostrils of the
dog pass out in mucus when the dog sneezes or are swallowed and pass
out in the feces. When these eggs are swallowed by suitable host
animals in eating contaminated vegetation, as by herbivores in grazing,
the eggs hatch and the larvae make their way, as a rule, to the liver,
lungs, and lymph glands and there develop to the infective stage. In
the United States these larval tongueworms are fairly common in
cattle in the South; in Europe sheep are the most common intermediate
hosts. In view of the fact that the larvae may also
occur in man, and that the adult is reported from
man in one case, this parasite must be looked on as
dangerous. Up to the present time it has been found
in the dog only in Georgia, but it undoubtedly has a
much wider distribution in this country, as the pres-
ence of the larvae in cattle shows, and failure to find
it is largely due to failure to look for it.

Symptoms.—Dogs infested with tongueworms may eto alt
show no symptoms or may have sudden attacks of (\atged. From
sneezing, coming on when the dogs are active for any yey
reason. There is often loud snoring, sometimes with almost complete
stoppage of breathing. The animal may rub its nose with its paws as
if to remove some obstacle. It is interesting to note that tongue-
worms have been found in dogs affected with what have been called
“running fits” or “fright disease,” a condition not yet very well
understood.: The same condition has been noted in dogs heavily
infested with hookworms, and relief reported after successful treat-
ment for hookworms. What relation these parasites or others might
have to ‘‘running fits’ is not known.

PARASITES AND PARASITIC DISEASES OF DOGS 33

_ Treatment.—No satisfactory treatment appears to have been estab-
lished. Unless the parasites could be removed by the injection of
some suitable substance into the nostrils, treatment would appear
to be surgical. In default of successful treatment, dogs known to
be infested with tongueworms should be destroyed on the ground that

they are carriers of parasites which are dangerous to man and injurious
to livestock.
COCCIDIOSIS

Cause.—Coccidiosis in the dog is due to the presence and effects of
very small protozoan parasites. There are four species of these para-
sites reported from dogs. Some of them occur in the epithelium of
the intestine and some of them under the epithelium in the submucous
connective tissue. The parasites undergo certain developments in
these tissues and multiply here. Ultimately they develop resistant
forms called oocysts (fig. 33) which pass out in the feces and serve to
infect other dogs. Cats are occasionally infected with coccidia but
such infections are likely to be overlooked. ,

Symptoms.—In light infestations coccidia may cause no perceptible
symptoms in dogs or cats, but in heavy infestations diarrhea appears
at the time when the oocysts are passing in the feces and it may be
accompanied by the passage of blood and gas.
There may be a slight rise im temperature during
this time. Under unfavorable conditions, as in
heavy infestations in very weak or young dogs
or those with secondary infections, the animals
may die. The diagnosis of coccidiosis depends
on the finding of oocysts in the feces.

Treatment —No effective treatment for coccid-
iosis in dogs or cats is known. However, the
disease appears to be self-limited, all of the
Lowers present Spagna in the ie OF snecne ema se coca
time to the oocyst stage and passing out. Hrom ~ ian, Isospora rivolta.
observations “ the senior author this will prob- oo
ably occur, as a rule, within 2 weeks. There is |
some evidence indicating that an attack of coccidiosis confers some
subsequent immunity. ‘The indicated treatment, therefore, is along
the lines of good care and nursing, the animal being fed nourishing
food in quantities suited to its condition and protected against un-
favorable conditions until the infection terminates. Such symptoms
as diarrhea may be controlled by appropriate treatment if necessary.
The premises occupied by infected animals must be re arded as in-
fected, and thoroughly cleaned; the use of strong, hot coal-tar creosote
dips appears to be of value. Heat and drying are destructive to
oocysts. As indicated in the introductory paragraphs, preventive
measures for this disease and other parasitic diseases are along the line
of sanitation, and sanitary preventive measures are primarily the
business of the dog or cat owner. In coccidiosis, as in the other
diseases, diagnosis and treatment are primarily the affair of the vet-
erinarian and the employment of a competent veterinarian is always
advisable when diseases are actually present.

34 CIRCULAR 338, U.S. DEPT. OF AGRICULTURE

CANINE PIROPLASMOSIS

Cause.—Piroplasmosis in the dog is due to the presence in the
red blood cells of a small protozoan parasite related to the organism
causing tick fever of cattle. This parasite is transmitted from
infected to healthy dogs through the bites of ticks. Several ticks have
been incriminated as vectors of canine piroplasmosis in various parts
of the world and among them is the brown dog tick, Rhipicephalus ©
sanguineus. It is probable that R. sanguineus is the important
vector of the disease in the United States, since this tick is common
in some parts of this country. (See p. 12.) The extent of canine

’ piroplasmosis in dogs in this country is not known, but one case in
Florida has recently come to the attention of the writers.? Cats are
not known to be susceptible.

Symptoms.—Canine piroplasmosis may be either acute or chronic.
In the acute form of the disease the infected animal may show increase
in temperature, reddening of the mucous membrances, increased
pulse and respiration, loss of appetite, and increased thirst. Jaundice
is present in about 50 percent of the cases. Acute cases frequently
terminate in death. /

In chronic cases fever may be present during the first days of the
infection, and in rare cases there may be an intermittent fever. The
animals become listless and the mucous membrane pale; jaundice is
usually absent in chronic cases. There is a diminished appetite, and
the infected animals become greatly emaciated. A positive diagnosis
can be made only by microscopic examination of the blood and finding
the parasites in the red corpuscles.

Treatment.—Trypan blue is said to be a specific in some forms of
canine piroplasmosis. The drug is used in the form of a 2-percent
solution in sterile distilled water. It is recommended that the powder
be finely triturated with a small quantity of cold water in a mortar and
more water added gradually until the dye enters completely into
solution, which is then made up to the desired percentage. The
solution should be filtered through filter paper and the filtrate auto-
claved at a temperature of 120° C. for 20 minutes. When cool, the
solution is transferred to sterile bottles which should be carefully
sealed. The dose of the solution that has been suggested for a dog of
average weight is 5 to 6 cubic centimeters injected intravenously.
One dose of trypan blue is usually sufficient to effect a cure in
infections with Babesia canis, one of the species causing canine .
piroplasmosis.

Tryparsamide has been reported also as being effective in the treat-
ment of canine piroplasmosis. The dose of the drug for a 25-pound
dog is given as 0.85 gram dissolved in 5 cubic centimeters of sterile
distilled water, administered intravenously. Best results are ob-
tained following the use of 5 injections with an interval of 5 days
between each injection. Other arsenical preparations also have been
recommended in the treatment of canine piroplasmosis.

2 This report is based on a case diagnosed by Dr. Paul Eaton of the Florida Department of Health, th
diagnosis being confirmed by Dr. G. Dikmans, of the Federal Bureau of Animal Paduitest Ene

ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE
WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary of Agriculture......_......-.____ Henry A. WALLACE.
Assistant Secretary...........---.______.. Rexrorp G. TuGweuu.
Director of Scientific Work__.__.__________ A. F. Woops.

Director of Extension Work____.-..______. C. W. WarsBurton.

Director of Personnel and Business Admin- W. W. SrockBERGER.
istration.

Director of Information........---- fei See M. S. E1sENHOWER.

Solicitor... ..-..2------2--.--------- cae Seta Tomas.

Agriculiural Adjustment Adnan. --- Custer C. Davis, Administrator.

Bureau of Agricultural Economics....------ Nits A. OLsEn, Chief.

Bureau of Agricultural Engineering.____--- 8S. H. McCrory, Chief.

Bureau of Animal Industry._.._...._-_--- Joun R. Mouuer, Chief.

Bureau of Biological Survey_.._......----- Jay N. Daruine, Chief.

Bureau of Chemistry and Soils_.......____- H. G. Knieut, Chief.

Office of Cooperative Extension Worth. csex2s C. B. Smiru, Chief.

Bureau of Dairy Industry-_...---.-.------ O. E. Rexp, Chief.

Bureau of Entomology..-..--.-..--------- Lee A. Strona, Chief.

Office of Experiment Stations.__.._-----.-- James T. JARDINE, Chief. .

Food and Drug Administration. _..._____-- Water G. CampBe., Chief.

Forest Service.__..--2-.----__--.--------- Ferpinanp A. S1tcox, Chief.

Grain Futures Administration.._......-.-- J. W. T. Duvet, Chief.

Bureau of Home Economies. ------- separ Lovise Sranuey, Chief.

TAD OTY eo ek eee tee oe oe CuaRiBEL R. Barnett, Librarian.

Bureau of Plant Treausieg bast eh obs sot os Se Knowues A. Ryerson, Chief.

Bureau of Plant Quarantine__.-.---------- A. 8. Hoyt, Acting Chief.

Bureau of Public Roads._._..--..-------- THomas H..MacDonatp, Chief.
' Weather Bureaw__----------------------- Wiis R. Gruae, Chief.

This circular is a contribution from

Bureau of Animal Industry_.------------- Joun R. Mouter, Chief.
Zoological Division. _.--.------------ M. C. Hatt, Chief.

35

U.S, GOVERNMENT PRINTING OFFICE: 1934

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