mprgtact ney Per, cert Pees eh > eer: rarer tes nae ‘4 piatke peeecrt iad _ haban tat Sepeey tg en femme 7 oka =e ey, gy a uch i terse mio et * oe cpt peta cote pos Sygrerereetenteey ane eens poche zs nae oa Re sitaterese cane * statverers taraementy Pat Shee ae ponies meeiaikis cobs aces ae ye os tr cot i u ab THis ris poet as: ie bepeey: ee on weigahen ed a pas GG eat ertenee re ere See 83 3 at es Gece errit ee Diet res aati robpes aoe Sra a pe per Ne attetire re ae, Pe eiate Seproeres 2 sae x eer se atta teeter ipsiee in Pree miata pein OR isere sph eine - aie ant eer steer ties wee beet apres iret setb ate : hp glide clone paps reper es eae cas are cert reiahena aa aEe ry fies Seger saapes int peal yee x ge th er ee Te a ered re ane eee phy fay hh ais chaime den Nba > be a riot he aeege ne | bbe py ia. eh fer oaearet Ory Telo.Tahe Seen repeat are Regs Sper eee eae thebrlehe iret res Saale pyedeonde Sesst ea aes = en Sitar Ree ieee Fedglgl Metin pop pige are a we & Gate CPA pep eeetats Parise pepe RCpS peated Saree tetera one ef peter yng oe fore nmerenss fof Bee Spies Sie 5 Before eee as eat ace eres nee eT a a armen em toca eee sale phos ‘4 on ume : wets a =) = ~ hee re mts optiler crenmrer let. ‘ ; oe ee pean ie: I saat Oe tel ars on = 2 aes pats Sp repeteht lake ~ we ae See ree aera ae ee ae Been a aeplgdinigdepdn! Sofa : Teme wecnne : iota cine anton at ae for opeot 4 icreeoeraaes peetate Sesceaces Spigle lil plop oad rego x A Aare eer Pe ge itr a wa atin mae PUES ah locaa he ac opt sagt taper page) fap pfs phoyptcpiaris eee Th pd elagrinath eas io rs see (Oe ep Sr a De ew ee eo Par Serer con cana CR ES "ter Firm os rs ae Armes Cornell University Library The pathology and differential diagnosis “aii Digitized by Microsoft® This book was digitized by Microsoft Corporation in cooperation with Cornell University Libraries, 2007. You may use and print this copy in limited quantity for your personal purposes, but may not distribute or provide access fo it (or modified or partial versions of if) for revenue-generating or other commercial purposes. Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® Digitized by Microsoft® Protozoa. DTS Fungi. Il. Bacteria. I? CAUSES OF INFECTIOUS DISEASES. Digitized by Microsoft® THE PATHOLOGY AND DIFFERENTIAL DIAGNOSIS OF INFECTIOUS DISEASES OF ANIMALS By VERANUS ALVA MOORE, B.S., M.D. Professor of Comparative Pathology, Bacteriology and Meat Inspection, New York State Veterinary College, Cornell University, Ithaca, N. Y. WITH AN INTRODUCTION BY DANIEL ELMER SALMON, D.V.M. Chief of the Bureau of Animal Industry, United States Department of Agriculture. ILLUSTRATED. ITHACA, N. Y.: TAY LOR & CARP ENTE R= 1902. Digitized by Microsoft® Digitized by Microsoft® TO DANIEL ELMER SALMON LARGELY THROUCH WHOSE LABORS THERE WAS ES- TABLISHED IN THE UNITED STATES DEPARTMENT OF AGRICULTURE THE BUREAU OF ANIMAL INDUSTRY WHICH HAS MADE POSSIBLE EXTENSIVE INVESTIGA- TIONS INTO THE NATURE OF EPIZOOTIC DISEASES IN AMERICA AND WHO FOR EIGHTEEN YEARS HAS DI- RECTED THESE INVESTIGATIONS THIS VOLUME IS DEDICATED. Digitized by Microsoft® Digitized by Microsoft® PREFACE. The literature on infection and the etiology and morbid anatomy of infectious diseases of animals is exceedingly rich in the results of new discoveries and important investigations. However, students just beginning this study and following a prescribed curriculum have not the time nor are they prepared to read with profit the detailed records of original research. Such publications seem to be better adapted for those doing advanced or graduate work. Furthermore, many of these publications are out of print and are only available for consultation. For these reasons it is believed that a volume containing the rudiments of the subject will be of use to the student and an aid to the teacher. Itisalso believed that such a work will be of assistance to practitioners. In preparing this volume the aim has been to bring to- gether in a concise form the fundamental facts in the path- ology of the more common infectious diseases of animals, especially those existing in the United States, with which sanitarians and the practitioners of comparative medicine must contend. To this end, the current literature, the reports of the investigations made at various Institutions and Experi- ment Stations, as well as the standard works on comparative pathology have been freely drawn upon and to all of which full acknowledgment is hereby made. In order to bring into consideration the clinical value of a knowledge of morbid anatomy, a few of the symptoms or ante- mortem manifestations have been included. It is hoped that this correlation of symptoms and lesions will stimulate a deeper Digitized by Microsoft® vi PREFACE interest in the study of comparative pathology and thus render it of more permanent and practical value for those entering into the practice of veterinary medicine. In selecting the subject matter care has been taken to avoid, as far as possible, the introduction of results concerning which there are controversies. It has seemed best to deal with those facts about which at the present time there is little or no doubt. After the discussion of each disease a few refer- ences to the literature are appended. ‘These are intended sim- ply to bring the attention of the student to a few publications respecting the cause and morbid anatomy, considered in the light of modern etiology, of the disease in question and toa few articles containing the results of original research. In order not to complicate or unnecessarily expand this text, a knowledge of general pathology and the principles of bacteriology has been taken for granted. The difficulties involved in the preparation of such a text are both numerous and obvious. The indication of errors or omissions with any other criticisms that will tend to better the volume and increase its efficiency for the student will be thankfully received. V. A.M. Digitized by Microsoft® TABLE OF CONTENTS. PAGE LOMSHU (ONE NCTC OSM WONTON ak ee Se ee eee be PST OE RoE EERE NCE gs © O KS eee seen ya eee ty ee eee xl INTRODUCTION xii CHAPTER I. GENERAL, CONSIDERATION CONCERNING ETIOLOGY, INFECTION AND SPECIFIC INFECTIOUS DISEASES. ( Etiology, Infection, Channels of infection, Wound infection, Bacteria causing wound infec- tion, Lesions presumably of wound infection origin that are recognized as distinct maladies, Botryomycosis, Omphalophle- bitis, White scours, Infectious suppurative cellulitis, Fistulous withers and poll-evil, Infectious mastitis, A specific infectious disease, The differential characters of a specific infectious disease, Cause for the variation in the course of an infectious disease, Grouping of specific infectious diseases) _________ -__- I CHAPTER II. DISEASES CAUSED BY STREPTOCOCCI -___----------. ~~ apnemeeeney Hy) Generaltdiscussioniol streptococci: 2202255252 ==) ass =an ts es 27 Sttangles!= =< 2 Soe ee ao oes Se eae sens seoseeceeescses 33) Equine contagious pleuro-pneumonia_______-__-_-__--- ------ 37 Apoplectiform septicaemia in chickens_________--. -_-_-. ----- 44 CHAPTER III. DISEASES CAUSED BY BACTERIA—GENUS BACTERIUM 47 Swilnes plac Ceeeeeseeeeans se ee ene ene eee pe eke te ene ames 47 Hemorrhagica septicaemia in cattle______._-__- ---. ---- ------ 68 Hera yA bee( Gh aKOp USS =e hs Pe he ee a Oe Se ee | i) JNGCM END He Ds eee ee Ene, ey BB ree eee ee eae 81 Infectious leukaemia in fowls -_ 98 Swine erysipelas_____- ope Ra 8 ee eee ee ek lle : CUR OLS eee a Se ee ee ee 113 FISTIDE TC Ll OSL meee ee eee ee ee = eee eee 127 Ovine caseous lymph-adenitis____--_. ---.------------------- 161 Asthenia 167 Digitized by Microsoft® vill CONTENTS CHAPTER IV. DISEASES CAUSED BY BACTERIA—GENUS BACILLUS -___ ------ ---~-- 169 Ja Koysew alae) hehe ees Shee ey See aS re ges BS ieee eee 169 Eel a tain Goer eee ene eee eee decrpberat Ssh dea peste tran Sentimental A ewlenek 185 Sym ptomaticcanthraxs2 222 oe eens Sa ee ee 195 CHAPTER V. DISEASES CAUSED BY HIGHER FUNGI 204 EA CLUTIOTILY:COS 1S eee eee eee ern en eT wee ee Sere pene eee oe ne 204 IGRAC ES 2 toes, Ramee EES, epee deren eM Sat cpa al tes Slit 218 BEM INOLY. COSTS poe ees eee ee eR ean SRS Une es 228 CHAPTER VI. DISBASES: CAUSHD, BY PROTOZO AL. = 22 coe. ae yaaa eee eee 256: DRS NS a I a 0 a ii ee er oeeaees prem Shem, LS) Infectious entero-hepatitis in turkeys_______________________- 252 ROU O2Y 8 Ae a ee ee cee eee tet ee oe I Ne A ey 265, ALS) QU 1.7 ese es ae a RE oe eR eh cree pecs ae we 27 1 CHAPTER VII. INFECTIOUS DISEASES FOR WHICH THE SPECIFIC CAUSE IS NOT VET LBP OPO) OSU OOS 2) USE a ele te eee Ree ee Re ee 252 Rinderpest -____- Se ee a ay ee 282 Contagious pleuro-pneumonia in cattle. _____. _-_-__. _- -- Le. 290 Boowandtimouthidiseas eases ee eee ee on ee 302 Ra LC Sys seers ates says ae SN wes arene et a Sr he oN OG Diphtheriadnetow seen eoesowae sence eeey ene seep es See een ae 325 Lt CT Zales eaten mee gee eens eee een aes ane Sete aE eee 334 MTD OLS UST Ta Toe eee ee ae ee ot 340 Infectious cerebro-spinal meningitis Sees. See] Gorustalkidiseasesinicattlesste= saa aes eas ees Cee ee 349 CHAPTER VIII. A FEW DISEASES CAUSED BY ANIMAL PARASITES ______ _____. -_____ 355 The nodular disease of the intestines of sheep and cattle______ 355 Nodulantacniasisiinefowlsssee-. = aaa een eon ee eee ee 360 AriCHIMOSiSt- a sa) sateen eens Le oe ee ewan pay eee 364 APPENDIX. TELS TENSES CFLS LO) IN oe as lene e eee 370 Digitized by Microsoft® ILLUSTRATIONS. PLATES. Bacteria, fungi and protozoa_________________._________. FRONTISPIECE fhuberculoussboyinesheant see sees omen ae eee en oe ee Il Tuberculous and healthy spleens, pig.____._-_______.__. _.______ Ill iuberculosisof lung spigees) sys ss 2 ee IV Mangus associatedtwithwleechesusss2 sense ese eee ee eV Aspereillareon em Onis see eee as ma eee ee ee ee Seen VI Mapishowin sRexastfevers lines eae seen as noes ey ae VII Diphtheria in pigeons FIGURES IN TEXT. PAGE I. Streptococcus of mastitis 16 2 Oe CLIO TNOTICOWLStId der eee pe ee eee ene eee ae een rene 17 3. Abscess in partially immunized rabbit ____. ____ _____. -______ 23 ay Morphology ofistreptococcuss= ss s2s5 = een ate seeaee nee 28 5 mebactenummolswinc plage ea ee= eae aes es oes Seen eee ee eS 6. Lung withinterlobular lymph infiltration ______._-__ -_______ 53 7. Lung showing emphysema in interlobular spaces______ _____- 54 8. Right lung of pig showing areas affected with swine plague___ 55 9g. Portion of lung showing hemorrhagic interlobularinfiltration. 58 to. Anthrax bacteria from an impression preparation________ -___ 83 Te eR CCL CPU TNA IUL UY CUS eee ete es oe an a ee arene EEO 12. Cover-glass preparation from anthrax blood______-~___--__-- 85 WEES LGLOELU IIDASCILECULUILULY. 1 UL 1 eee ee re ee 99 14. Bacterium sanguinarium in the liver___._.--_-_-----.------- 99 15. Temperature chart of fowl affected with leukaemia_._._.._.-_ 100 16. Diseased blood in infectious leukaemia______ ____ -----~- ------ 102 17. Congested liver in infectious leukaemia -______. |----------.- 103 18. Phagocytic action of leucocytes on the red blood corpuscles__ 104 Ho. Bacterium: of swineerysipelas:22- =. -2.=5- 2-2 -2<-25-s29-22-= 108 2G. “BUClevIUIE WAU. ce 2 BS S38 ees ea eS 115 oh, ANE CEM Ceylon, MAES gs. so es eat ea eee ee ee eee! ORS) 22 mE AT Cy aiCutaneOus, © landerse-ssesoseeas Sonne ease seers nea 120 DEE A CLORD INL DC KCL OS US Ree a ene Mey eee ae ae RES eS 131 24. Lymph glands on side of cow’s head____.___ -_---- .--- ------ 137 25, Dorsalhaspect of bovineWdungs 222 222. 2222 e882 fae oe noe = 138 26. Bovine tracheal and bronchial lymph glands__.._-_------------ 139 27, Posterior mediastinal glands 222. 22. -£.2---. 2222-222 -=---- 140 ‘28. Suppurating tubercular focus, cow’s lung __..-----------.--- 141 29. Tuberculous omentum, cow_._--.-- --------- ---------------- 142 Digitized by Microsoft® W & DW G2 Ww GQ nw AO = Ww & DI DH Ww Ww Nome ise) RD ie) STL ROSE ST USS vom O oD ILLUSTRATIONS Small tubercular nodules, parietal pleura, cow -___ --___- ---_-- Beginning tubercle in spleen ____-___ -___ ees eee Section:of tuberculousllune, (cow 2.22 2222-8 se eos eee en ae Tuberculows; spleen pigs 2s. 2 aaes poesia e eee ene Chart showing the effect of cold water on temperature______ _ Non-tubercular temperature reaction Chart showing tuberculin reaction 2 <2 2222522522. ==. Bacterlumots Preis7 sease aes ea eee eee es OGLE PLU ESL ILE TUL CL Cte Re ey eee a ge I Bacillus of hog cholera. Wiceratediintestineinhog:ch olerals. ss. ae s== as ae Spleen of pig, normal and with hog cholera._____ -----. ----- BOCUUUSRLCLOND = = ae eee ee ee eee ee ae Bacillus‘of symptomatic anthrax _ 52-2 2-22. 225-2552 eee RRGLV a UT GUUS aves ea ae ee eee eee ee ee Actinomycosis, head of steer____ -___ ___- Section of actinomycotic jaw __ Actinomycosis of upper jaw -_---- ---- .. Achnomiy.COSISsiny (ON SM Glee a = es ee ee eeches lesionstinelippohMbOrse sess y eee a ees Teeches;lesionsiiny lipsot miorseeees 2a eee ee ee Isolatedsnodule; from lesion 7=2-=- = 222.) 2 pas eee Set Club-like ends of hyphae fungus, ‘‘leeches”’____ .___-___ ----- Section through nodule, ‘‘leeches’’________ UH OP LO SHLOMO LE CNTLLILUL TU ean ee = ye ee Coceusiform-of Piroplasma bigeminuni_—_—__ = Texas fever parasite:in, bloodof kidney =... =. ==. ===. 2 Coccus form of Texas fever parasite in kidney ______._______- Capillary of heart showing invasion of corpuscles with Piro- laSmagh IS ergs Sen ee mene eee ee ey aes Adultmale tick; Boophilustbovisisss: 2222s. e: a2 ose see ees Bullisuitenincatrotmibkexas! Tevet =ste a see ane e ents: See ee os Adulttemale tick, Boophilus bovis2.— 222. 2222-225 Sass See oe Eggs and young tick, Boophilus bovis.___ -_____ -___ -__-____ PAGWOCO Us gILCLE EY L0 1 Ses Seana ee eae eee ee a | aI Oi Caeca of turkey with lesions of entero-hepatitis______________ Caecum showing ulcers in entero-hepatitis._.. _-_-__ ________ Liver of turkey affected with entero-hepatitis_________. ______ LLY PEI OSUULORSE UR IUS Les eee ee eee 3 eee ee Photograph of Trypanosoma in blood.___..-___. -___ -___ --___ Nodular disease in sheep, cross section of intestine Cross section of worm nodule_____- faeniasissink Chi Clem s a= seat ree merce a eee pees eee Sections showing nodule and worm________-___________-____ Encapsuled Trichinella spiralis _____ __ Digitized by Microsoft® A LIST OF REFERENCE BOOKS. BOULEY ET REYNAL.—Nouveau Dictionnaire pratique de Médecine de Chirurgie et d’Hygiéne Vétérinaires, CapkEac.—Encyclopédie Vétérinaire. DIECKERHOFF.—Lehrbuch der Speciellen Pathologie und Therapie fiir Thierarzte. ELLENBERGER, SCHUTZ UND BAuM.—Jahresbericht tiber die Leistungen auf dem Gebiete der Veterinar-Medicin. FLEMING.—A manual of veterinary sanitary science and police. FRIEDBERGER UND FROHNER.—Lehrbuch der Speciellen Pathologie u. Therapie der Hausthiere. GALTIER.—Traité des Maladies Contagieuses et de la Police Sanitaire des Animaux domestiques. Kirr.—Lehrbuch der Pathologischen Anatomie der Hausthiere. Law.—Veterinary Medicine.—( Especially Vol. IV.) LUBARSCH UND OSTERTAG.—Ergebnisse der Allgemeinen Pathologie und Pathologischen Anatomie des Menschen und der Tiere. OstERTAG.—Handbuch der Fleischbeschau fiir Tierarzte, Arzte und Richter. REYNAL.—Traité de la Police Sanitaire des Animaux Domiestiques. SCHNEIDEMUHL.—Lehrbuch der vergleichenden Pathologie und Therapie des Menschen und der Hausthiere. WaALLEY.—The four bovine scourges. For bibliography on all medical subjects, see Index-catalogue of the library of the Surgeon-General’s office. Annual Reports, Special Reports and Bulletins on Animal Diseases issued by the Bureau of Animal Industry, U. S. Department of Agricul- ture, Washington, D. C. Proceedings of the American Veterinary Medical Asscciation. The Bulletins on Animal Diseases issued by the various State Agri- cultural Experiment Stations. Digitized by Microsoft® INTRODUCTION. An elementary treatise on the pathology of the infectious diseases of animals—a treatise that states briefly, clearly and comprehensively all that is known, and excludes all that is not known—has long been needed not only by the students who are beginning this interesting subject, but by members of the veterinary profession who, as practitioners, investigators or teachers, wish to learn in the shortest time the present con- dition of our knowledge. A work which supplies this need will be welcomed and appreciated. There are few subjects more important to Americans than a thorough comprehension of the infectious diseases of animals. An enormous amount of money is invested in the domesticated animals in the United States, and the security of this invest- ment depends very largely upon our ability to protect these animals from infectious diseases. There are many diseases of this class which spread among animals as smallpox, bubonic plague or cholera spread among mankind ; and it requires a thorough knowledge of all the characteristics of such diseases to guard against them, to recognize them when they appear or to control them. For a period already too long, exact knowledge of these diseases has been confined to a comparatively small number of men ; but with the great property interests at stake itis ex- tremely desirable that this information should be distributed, that not only responsible officials but every practitioner should share it. With not far from three thousand million dollars worth of farm animals in this country, and with a single disease Digitized by Microsoft® INTRODUCTION Xili that sometimes destroys a hundred million dollars worth of property in a year, it is not difficult to see the value of that precise knowledge which is required to deal promptly and efhiciently with these plagues. It is a narrow and incorrect view to hold that the farmer who owns these animals is the only one who suffers from the ravages of the diseases which destroy them. Animal products constitute a large part of the national food supply. If this food supply is diminished, made dearer and more difficult to obtain, want, misery, disease and death among mankind increase. At first the effects of a scarcity of the food supply may be almost inappreciable and felt only by the very poor; but as the con- ditions of famine are approached, suffering is multiplied and intensified until whole communities are prostrated or destroyed. An abundant supply of wholesome and nutritious food is, there- fore, an essential condition of the welfare and prosperity of a people. The great commercial operations of nations also depend to a great extent upon the good condition of animals. When all of the horses are disabled by an epizootic, as they have been on rare occasions by influenza, the delivery of purchased goods has nearly ceased, the shipments of flour, iron, machinery and other products have been temporarily arrested and busi- ness has been almost at a standstill. Again, it should be re- membered that we export annually from the United States forty million dollars worth of live animals, one hundred million dollars worth of meats, fifty-five million dollars worth of lard, tallow and other animal fats, and nine million dollars worth of dairy products. Let this trafic be stopped by a shortage of supplies or by prohibitive orders of other nations on account of the unrestrained prevalence of infectious diseases, and the earnings of steamships, and rail-roads, and banks, and com- mission houses, are at once diminished ; men employed in these Digitized by Microsoft® X1V INTRODUCTION enterprises are discharged, and in innumerable ways the wel- fare of people who have no part in the ownership of any of these animals or their products is affected. Finally the most serious of all, is the case in which the animal plague, in addition to being destructive to animal life, is communicable to and fatal to man, as is’true of anthrax, rabies and tuberculosis. Such diseases destroy property, dis- turb business, lessen the food supply, and directly threaten human life. What more is needed to impress upon the reader the supreme importance of studying and understanding the infectious diseases of animals? The pathology of these diseases is in itself a large subject. Investigations concerning it have extended over more than a century of time and the literature of the subject is enormous. To concentrate this knowledge, to select the truth and discard the errors, and to develop a concise and systematic treatise is a task of great magnitude and one which has required much labor and thought. ‘The writer has not seen the manuscript, but, from his long and intimate acquaintance with the author, he feels sure that the work has been patiently, carefully, intelli- gently and thoroughly done, and that it will be favorably received. D. E. SALMON. Digitized by Microsoft® CHAPTER I. GENERAL CONSIDERATION OF ETIOLOGY, INFECTION AND SPECIFIC INFECTIOUS DISEASES. S1. Etiology. The development of the science of bac- teriology, together with a knowledge of the parasitic protozoa, has demonstrated that a large number of the infectious dis- eases are the direct result of the invasion of the animal body by certain species of microorganisms. A specific etiology which teaches that for each of the various epizootics we have a sin- gle, definite cause has become recognized and accepted by all pathologists. Although there are a number of distinct diseases for which such a specific agent has not been found, the evi- dence in the very nature of the maladies, is conclusive that for each of these such an etiological factor exists. In studying the pathology of infectious diseases the idea of a definite and adequate cause should be kept in mind. Itis no longer justifiable to attribute them to an unfavorable en- vironment, poor hygiene, or improper sanitation, conditions which may aid the specific cause but which cannot supplant it. It isoften a troublesome task to differentiate between the morbid affections, often fatal in their results, brought about by improper care and food, and the maladies dependent upon a specific cause. The reason why many of the former theories accepted unsanitary conditions, certain kinds of food or other similar agencies as the etiology of distinct, infectious diseases, is found in the fact that the infectious microorganisms were and still are often transmitted to the individual through such channels. It is important, therefore, that the limitations of both the exciting cause and the environment should be fully taken into account. Although for certain diseases such as rinderpest and rabies we do not know just what the specific Digitized by Microsoft® 2 ETIOLOGY cause is, the fact that its location in the body of the diseased animal is known, that with these morbid tissues the disease can be produced in healthy animals and that without these definite infections, no matter what the surroundings are, they cannot be made to develop, argues against extraneous conditions as exciting causes. The mysteries which formerly surrounded the origin, the course and the disappearance of animal plagues have in a large degree been cleared away and in their place we are con- fronted with the problems involved in the life history and the possibilities of invading microorganisms. In fact during the last few years the biological sciences have been brought into immediate use by the pathologist. Etiology has become per- manently linked to microbiology so that in seeking for the specific cause of an infectious disease we look for some spe- cies of organic life which may belong either to the animal or to the vegetable kingdom. The fact that certain animals and plants have become, if they were not in the beginning, para- sitic on other larger and higher forms of life has long been recognized, but the idea came later, that the various infections giving rise to a wide series of phenomena, known as symptoms and morbid anatomy, were actually and simply the results of the invasion of the individual with living microscopic plants (bacteria) or animals (protozoa). It is likewise true that for many of the disorders consisting of changes recognized in the terms of general pathology, the cause may be found in the con- ditions of life under which the individual has been forced to exist. Etiology, therefore, in a broad sense, includes both the infecting or parasitic microorganisms which cause infections and produce the specific infectious diseases and poor hygienic, unsanitary conditions and physical forces which may produce non-specific morbid changes often sufficient to cause death. $2. Infection. The term infection has come to be gen- erally understood to mean the entrance into the animal body, from without, of living microorganisms capable of multiplying within the living tissues and of producing in consequence thereofa local ora general diseased condition or the death of the individual. The invading microorganisms may belong to any Digitized by Microsoft® INFECTION 3 one of the three great groups of microscopic life, namely, bac- teria, higher fungi, or protozoa. It iscustomary and convenient, if not altogether logical, to limit the term microorganism to these forms excluding altogether the entozoa and other animal para- sites most of which are not microscopic in size. A diseased condition produced by substances not capable of reproducing themselves as, for example, organic or inorganic chemical compounds, is an intoxicative process. In an infection, the immediate cause of the symptoms and morbid changes in the tissues is an intoxication due to the action of the metabolic products (toxins) of the invading microorganisms. The the- ories of their mechanical interference with the normal functions of the body or that they absorb the nutriment thus depriving the tissues of necessary food wait for demonstration. The re- sults of infection vary in their manifestations. If the invading organisms remain at the point of entrance and produce local tissue changes, the condition is spoken of as a wound infection ,; if the invading bacteria become widely distributed in the cir- culation and tissues, the condition is known as sepéccaemia , if the infecting bacteria remain at the point of entrance, multiply there elaborating a toxin which is absorbed and which causes symptoms and possibly death, the condition is a fovaemia ; if the invading organism happens to be that of a specific dis- ease, such as the bacterium of anthrax, giving rise to a defin- ite series of symptoms and lesions, the affection is designated a specific, infectious disease. Through the agency of metas- tasis, invading microorganisms may be carried from the point of introduction to other parts of the body where they may be- come localized, multiply and give rise to any one of many forms of lesions. It may happen that the point of entrance is so obscure that the resulting morbid changes are not easily traced to an external infection. There are many illustrations of this in comparative pathology such, for example, as suppur- ative cellulitis. For convenience in discussion, infections may be divided into the two clinical groups, namely, wound infec- tions and specific infectious diseases although in certain in- stances they cannot be separated. Digitized by Microsoft® 4 INFECTION In arriving at a clear understanding of the nature of in- fections, it is well not to be too closely circumscribed by classifications. It is better to look upon them as a series of processes going on in the animal world due to the activities of infecting or parasitic microorganisms. In other words, the lesions following an infection or a specific infectious disease are simply the results of parasitism. In the study of the various forms of infection in the lower animals, lesions have been found to contain, apparently as their causative factors, bacteria which suggest at least that certain of the supposed saphrophytic organisms may, under certain con- ditions, become parasitic and cause infections resulting in more or less local or generalized disturbance. Many lesions seem to be produced by bacteria which are harbored normally upon the skin. When these organisms are introduced by accident into the living tissues they multiply and acquire, if they did not already possess it, the power to produce tissue changes. We cannot, therefore, dismiss the subject of infection without a passing consideration of the possible etiological significance, under certain conditions, of many ordinarily considered harm- less species of bacteria with which the animal body is con- stantly surrounded. In the search for the cause of many le- sions supposed from their nature to be infectious, or in apply- ing methods for their prevention, it is well to take into consid- eration all microorganisms which might possibly be the caus- ative factors and not mit the search to the detection of the already recognized pathogenic species. Recent investigations point to the conclusion that frequently domesticated animals suffer as the result of the invasion of bacteria at present not listed among the pathogenic microorganisms, and what is true in this regard for bacteria, may be hypothetically applied to the higher fungi and to the protozoa. § 3. Channels of Infection. There are a number of ways by which microorganisms may be introduced into the living tissues of the animal body. The more common of these areas follows, namely : (1) Through the digestive tract, Bacteria gain entrance into the tissues from the digestive tract where they have been Digitized by Microsoft® CHANNELS OF INFECTION 5 brought with the food or water. Hog cholera infection is a good illustration of this mode of entrance. (2) Through the respiratory tract. Bacteria are taken into the lungs where they are brought with the inhaled atmosphere. Pulmonary tubercular affection is often brought about in this way. (3) Through abrasions of the skin. ‘The wide distribu- tion of bacteria in nature renders it highly probable that in all wounds of the integument microorganisms will reach the fresh tissues. They may come from the cutting or tearing implement, the particles of dirt which may fall into or upon the cut sur- face, or from the ducts of the glands of the skin itself. It may happen that the fresh tissues thus exposed are infected with one, or, with several species of bacteria. It may be that one or more of these species may be destroyed by the living juices of the body or by the leucocytes, or, again it is possible that, from their saprophytic nature, they may not be able to mul- tiply in this new environment ; in either case the infection is of no significance and clinically would not be recognized. It may happen that only one species of the infecting bacteria multiplies and produces the morbid changes. This would be a single in- fection. If, however, two or more species co-operate in the pro- duction of the lesions, it is called a mixed infection. This term is often used to designate the condition where one species may be responsible for the tissue changes although other bacteria are present but in an accidental or passive way (5 4). (4) Through the generative organs. Infection of the re- productive organs takes place in certain instances where they are the seat of the disease. This is especially true in case of maladte du cott. (5) Through the agency of insects. Some insects carry the virus of certain diseases from the infected and introduce it into the susceptible individuals. Thus the mosquito carries the plasmodium of human malaria, the cattle tick the piroplasma of Texas cattle fever and flies are often the introducers of pathogenic bacteria, such as those of anthrax (§ 76). ; (6) Transmission of the virus from the parent to the foetus. Occasionally the young of diseased parents are born infected Digitized by Microsoft® 6 WOUND INFECTION with the disease with which one or both of its parents were suffering. In these cases the specific bacteria were transmitted either from the sire at the time of coition, or later to the foetus in the uterus from the dam. It is important not to confuse these rare cases with those in which the offspring are born uninfected but subsequently contract the disease. Many of the so-called hereditary diseases are the result of post natal infection. $4. Wound infection. Wound infections are the direct results of the entrance of certain microorganisms into trau- matisms and operative incisions. They fall very naturally into two classes namely, (1) those producing acute or more chronic inflammatory processes usually leading to suppuration and finally healing by granulation, and (2) infections which may in the beginning appear like the first or, cause so little disturbance as to be unnoticed at the time, but sooner or later result in a local or remotely situated lesion or lesions. Fre- quently these are recognized as distinct diseases although in some cases, such as scirrhous cord, the origin is easily traced to an operation where infection was possible. In this second group of wound infections there are in addition to the scirrhous cord or botryomycosis, infectious cellulitis of cattle and sheep and still other disorders which may not seem to be dependent upon wound infection but which the results of re- cent investigations suggest as their primary cause. These af- fections will be treated separately in subsequent paragraphs but their relation to wound infection renders them worthy of note in this connection. A third class should be mentioned, namely, those specific diseases such as tetanus and symptomatic anthrax where the virus is supposed always to be introduced through a wound either in the skin or mucous membranes. $5. Bacteria causing woundinfection. A large num- ber of species of bacteria and a few fungi are included among the organisms which are known to produce wound infections in animals. Usually, however, the forms encountered are micrococci, especially those belonging to the staphylococcus group, streptococci, a few bacilli, especially those belonging to Digitized by Microsoft® BOTRYOMYCOSIS i the colon group, and a few species of the genus pseudomonas Fungi and protozoa are rarely found in wound infection le- sions. Many of the specific pathogenic bacteria may be intro- duced through wounds (§ 3). As a rule, it seems to be true that in the domesticated animals as in man the pyogenic bacteria are the most common and important wound infecting microorganisms. In open wounds these are, of course, asso- ciated with a very large number of ordinary saprophytic bac- teria. Frequently in closed lesions nonpathogenic organisms are present in addition to the seemingly causative factors. It is worthy of note, that it appears to be impossible to predict from the general character of the lesions, the kind of bacteria which are producing them except it be in case of certain spe- cific infections like tuberculosis or actinomycosis. $6. Lesions presumably of wound infection origin that are recognized as distinct maladies. It has already been stated that the lesions following wound infections may be brought about by a variety of bacteria and also that certain of these diseased processes are sometimes recognized as distinct maladies. There area number of affections which belong to this class. From some of these, such as botryomycosis, a sup- posedly specific organism has been isolated and described. A number of workers, however, have found that other bacteria may produce apparently the same morbid conditions. The more important of the affections which seem to be directly traceable to wound infection will be briefly described in the light of re- cent investigations. It should be stated, however, that the amount of work that has been done on these subjects is not sufficient to render the results in any way conclusive, but rather to suggest the lines along which valuable and conclusive findings may be expected in the future. §7. Botryomycosis. This name has been given toa variety of lesions found more commonly in the horse but occur- ring also in cattle, swine and other animals. The thickened spermatic cord (scirrhous cord ) which sometimes follows cas- tration is the most common form of thisdisease. Practitioners often designate as botryomycosis certain closed abscesses occur- ring in the subcutaneous or intermuscular tissue. Abscesses Digitized by Microsoft® 8 BOTRYOMYCOSIS and nodules found in the internal organs have been included under this caption. Several investigators have isolated from these lesions a species of microorganism which appeared to stand in a causative relation to them. It was first described as Zoogloea pulmonis equi, in 1870, by Bollinger, who found it in the nodules in the lungs of a horse. More recently he has re- named it Botryococcus ascoformans. Rivolta designated it Des- comyces equi. Rabe proposed the name J/rcrococcus botryogenes and Johne has called it A7. ascoformans. The results of other investigators throw some doubt upon the specific nature of these lesions. Kitt, Hell, deJong, Gay and others have found in them micrococci which do not differ from J/. progenes aureus. The writer has failed to find J/. ascoformans but has isolated in its stead pyogenic micrococci and streptococci. In one very interesting case of thickened cord, the writer found masses of a fungus resembling that of actinomycosis within the pockets of spongy tissue sprinkled throughout the thickened fibrous cord. Bacteria were not found in this case. In the closed abscesses in the connective tissue pyogenic bacteria have been found, ex- cepting in certain cases of long standing where the cultures gave negative results. Investigations which have been made into the bacterial flora of the skin of the horse show that pyogenic bacteria are frequently present in the deeper layers of the epidermis, in ducts of glands and about the hair shafts. With the possibility of infection from the integument plus all the other chances of having members of this and other groups of bacteria introduced into the body there seems to be abundant opportunity for infection by a variety of species. The evi- dence at hand points to the conclusion that botryomycosis is the result of wound infection, and that several species of micro- organisms are capable of producing it. § 8. Omphalophlebitis. This affection which is com- monly called navel-ill, consists of suppurative lesions in young animals caused by pyogenic bacteria. In the horse they are most often localized in the joints of thelimbs. In certain other species the lesions are quite as likely to be situated elsewhere in the body. In some cases the morbid changes are restricted to subcutaneous and intermuscular suppurative cellulitis. Digitized by Microsoft® OMPHALOPHLEBITIS 9 The infection takes place in the umbilicus. As the cord is severed in the field or stable many species of bacteria may gain access to the end of the exposed, and freshly severed cord. In the colt, a streptococcus seems to be the most com- mon species of bacteria capable of producing the joint ab- scesses. In the lamb, a variety of the colon bacillus has been associated apparently as the etiological factor with the subcu- taneons cellulitis. The lesions resulting from naval infection illustrates in a most excellent manner the extent to which certain pyogenic bacteria gaining access to the body may extend by metastasis to places remote from their entrance and produce diseased foci. In cases of navel-ill, the umbilical vein contains a large number of bacteria. The writer has found that in colts very few if any of the bacteria (streptococci) producing the joint lesions could be found in the parenchymatous organs. Occasion- ally one or two of many tubes of media inoculated from the liver would develop into cultures of the infecting organism. In this disease, where many species of bacteria come into com- petition, one is impressed with the fact that seemingly very few of the ordinary bacteria are capable of gaining an entrance into the circulation or, at least, are possessed of vital powers sufficient to resist the destructive forces of the living animal body. ee ees Ddad, Tey - == 7 INS -T_Dded 0) (eat iz bes Eee \ eA 109 H at ' / roe AZ an 1 4 f\ i a —— 7 p—™ aol 107 [Ne C1 A [-— MW r- 106 a Fic. 15. Yemperature chart of two cases of infectious leukaemia artificially produced in fowls. Although the course of the disease in different fowls is usually constant, there are many variations. The time re- quired for fatal results is from two to three weeks, but ordinarily death occur in about eight days after feeding the cultures. The rise in temperature can be detected about the third day and ex- ternal symptoms about the fifth or sixth, occasionally not until a few hours before death. The symptoms observed in the cases produced by feeding correspond with those described by the owners of affected flocks. As indicated in the inoculation experiments, the symp- toms following the intravenous injection of the virus were, as Digitized by Microsoft® MORBID ANATOMY IOI would be expected, considerably modified from those in fowls which contracted the disease by the ingestion of cultures of the specific bacterium. $87. Morbid anatomy. The only constant lesions found in the fowls which contract the disease naturally, as well as in those fed upon the virus, are in the liver and blood. The liver is somewhat enlarged and dark colored. A close in- spection shows the surface to be sprinkled with minute grayish areas. The microscopic examination shows the blood spaces to be distended. The hepatic cells are frequently changed, so that they stain very feebly, and not infrequently the cells are isolated and their outlines indistinct. Occasionally foci are observed in which the liver cells appear to be dead and the in- tervening spaces infiltrated with round cells. The changes in the hepatic tissue are presumably secondary to the engorge- ment of the organ with blood. The rareness with which the intestinal tract is affected in both the natural and artificially produced cases is exceedingly interesting and important for the differential diagnosis. There is in most cases a hyperzemia of the mucous membrane of the colon, but this condition is not uncommon in the healthy indi- vidual. The kidneys are generally but not uniformly pale. They are streaked with reddish lines, due to the injection of blood vessels. In section the tubular epithelium appears to be normal. The kidneys seem to be, from the number of bacteria in the cover-glass preparations, especially favorable for the localization of the specific organism. The spleen is rarely dis- colored or engorged with blood. The lymphatic glands are not appreciably enlarged in any individual examined. The lungs except in chronic cases are normal. The heart muscle is usually pale and sprinkled with grayish points, due to cell infiltration and necrosis. ‘These lesions are so common that it seems safe to consider them characteristic manifestations. Death usually occurrs in systole, the auricles containing very little thin, unclotted blood. The brain and spinal cord are unaffected. The most important alterations are found in the blood. These consist of the gradual disappearance of the red cor- Digitized by Microsoft® 102 INFECTIOUS LEUKAEMIA puscles and increase in the number of white ones, as deter- mined by blood counts made daily or every other day, from the time of inoculation or of feeding the virus until the day of death. The diminution in the number of red corpuscles and the in- crease in the number of white ones are illustrated in the blood count of two cases of artificially produced disease. (p. 105). In carefully heated cover-glass preparations of healthy fowl blood stained with methylene-blue and eosin, the nuclei are colored a deep blue, and the cellular protoplasm surround- ing the nucleus is stained by the eosin. In similar prepara- tions made from the blood of the affected fowls there area greater or less number of corpuscles which do not take the eosin stain. In these the portion of the corpuscle surrounding the nucleus remains unstained or becomes slightly tinted with blue. It occasionally t Sse paramere rare contains one or more vacu- oles, and the margin is fre- quently broken. In some in- stances a considerable por- tion of the corpuscle has disappeared, leaving a few free nuclei. The apparent Fic. 16. Blood from a well ad- dissolving away of the red vanced case of infectious leukaemia corpuscles has been fre- Showing changes in red corpuscles and increase in number of leucocytes. quently observed, and cor- puscles showing the inter- mediate stages are readily detected in carefully prepared specimens. The cause of the destruction of the red corpuscles is not yet satisfactorily explained. In his report on fowl cholera, Salmon illustrates leucocytes surrounding the red corpuscles, but the marked diminution of the red cells was not deter- mined. He speaks, however, of the pale color of the blood. In Digitized by Microsoft® MORBID ANATOMY 103 fresh preparations of the blood, portions of red cells may be seen within the granular leucocytes. The determination of the extent of this mode of destruction of the red corpuscles neces- sitates further investigation. TABLE SHOWING CHANGES IN THE NUMBER OF CORPUSCLES. Fowl] No. 82, inoculated in the wing vein, February 6. | Number of |Number of Tempera- redcor- | white cor- Date | ture (°F.) | puscles puscles Remarks perc. mm. |pere. mm. Feb. 6| 107.4 | gi744.a4d | 21,222 | Well. = 7 109 3,417,391 26,087 Apparently well. 8 108.2. | =2,784,700 55,000 Do. 9 | 108.4 2,807,692 76,925 Do. II 107.4 3,481,818 90,909 | Feathers ruffled ; refuses food. 13))| 10,2 2,133,333 100,000 | Very quiet ; comb pale. 14 108 2,530,000 140,000 Fowl died later in the day. Fowl No. sor, fed culture March 26. {Number of Number of | Tempera- red cor- white cor- “ rs Date ture (°F.) | puscles puscles | Remarks. |per c. mm. per c, mm. | Mar. 26 | 106.2 | 3,534,000 | 18,940 | Well. 28 110 2,430,000 70,000 | Fowl eats very little. Apr. 2 110.6 1,684,210 80,000 | Blood very pale ; fowl weak ; refuses food. 3 106 | 1,745,000 | 245,432 | Very weak; many red corpuscles at- tacked by leucocytes. Aa) |Sesewes-=222|ees2oeee= + -|\se2o=aoa==-= | eoundidead: In fresh preparations of the blood of affected fowls examined in Toisson’s fluid, red corpuscles which take the violet stain more or less intensely throughout are frequently observed. In the blood of poultry two distinct classes of white corpuscles are conspicuous. The first which predomin- ates in numbers, contains from one to four nuclei, and the cytoplasm is sprinkled with a variable number of round, elongated, or spin- dle-shaped bodies. In the Fic. 17. Section of chicken’s liver fresh condition they are showing engorgement of blood. Digitized by Microsoft® 104 INFECTIOUS LEUKAEMIA highly refractory. They stain with eosin, and if the prepara- tions are heated sufficiently they will retain certain of the aniline dyes. The other class consists of round or nearly round cells which take the blue stain feebly. Usually it is difficult to detect the nucleus, although it is occasionally distinct. Between these two types there are many varieties. The leucocytes containing the spindle-shaped bodies appear to be the phagocytes as they were the only ones which were observed to attack the red cor- puscles. Bacteria have not been demonstrated in these cells, although their presence has, in several cases, been suspected. From the appearances observed in the red blood corpuscles it | Fic. 18. The phagocytic action of the white blood corpuscles upon the red ones in case of advanced leukaemia. The changes represented from 1 tog took place in 35 minutes. seems highly probable that phagocytosis plays a comparatively large part in their destruction. Another hypothesis is also sug- gested, namely, that a toxin produced during the multiplica- tion of the specific organism has this effect on the red corpuscles. In the fresh preparations we can observe the phagocytes attack- ing the red cells. In the stained ones mutilated red corpuscles and free nuclei are present. The hypothesis is suggested that the leucocytes partially digest certain of the red corpuscles in their attack upon them. Whether these changes are entirely attributable to the phagocytes is still an open question. Digitized by Microsoft® DIFFERENTIAL DIAGNOSIS 105. In the blood from healthy fowls it is comparatively rare to. see one of the white corpuscles attacking a red one. As the disease progresses, however, this warfare becomes very con- spicuous, owing perhaps to the increased number of the color- less cells. Up tothe present the study of these corpuscles has not been extended beyond the observation of the general ap- pearance of these structures, and no attempt is made to explain the apparently marvelous increase in the number of the leuco- cytes. Itis an interesting and as yet unexplained fact that the increase in the white corpuscles is apparently restricted to: those containing the spindle-shaped bodies. § 88. Differential diagnosis. Intestinal disturbances, especially diarrhoea and fowl cholera, are the diseases liable to be mistaken for infectious leukaemia. A comparison of the important changes in the morbid anatomy in fowl cholera as described by European writers and in the disease under consideration can be made from the appended columns, in which their more characteristic lesions are contrasted : Lesions in Fowl cholera. | Lestons in infectious leukaemia. *, 1. Duration of the disease from a 1. Duration of the disease from few hours to several days. a few hours to several days. 2. Elevation of temperature. | 2, Elevation of temperature. 3. Diarrhoea. | 3. Diarrhoea very rare. 4. Intestines deeply reddened. | 4. Intestines pale. 5. Intestinal contents liquid, 5. Intestinal contents normal in mucopurulent, or blood consistency. stained. 6. Heart dotted with ecchy- 6. Heart usually pale and dotted moses. with grayish points, due to cell infiltration. 7. Lungs affected, hyperzemic or 7. Lungs normal, excepting in pneumonic. | modified cases. 8. Specific organisms appear in 8. Specific organisms compara- large numbers in the blood tively few in the blood and organs. and organs. g. Blood pale (cause not deter- | .9 Blood pale, marked diminu- mined ). tion in the number of red ae | corpuscles. 10. Condition of leucocytes not | |. Increase in the number of determined. | leucocytes. Digitized by Microsoft® 106 INFECTIOUS LEUKAEMIA Attention should be called to the fact that as yet there seems not to have been a careful study of the condition of the blood in fowl cholera. Salmon observed many changes in this fluid which may have been similar to or identical with those herein recorded. The difference between the specific organism of these two diseases can be readily appreciated by a comparison of the more diagnostic properties of each; they are arranged in par- allel columns, as follows : Bacterium of fowl cholera. Bacterium sanguinarium. 1. Bacterium short, with oval 1. Bacterium short, with ends ends. oval or more pointed. 2. It usually appears singly in 2. It usually appears in pairs tissues. | united end to end or in clumps in tissues. 3. Ordinarily it exhibits a polar 3. It gives a light center, with stain. (From tissue. ) uniformly stained peri- phery. (From tissue.) Rarely a polar stain is observable. 4. Grows feebly or not at all on 4. Decided growth on alkaline gelatin. gelatin. 5. It does not change milk. 5. Saponifies milk. 6. Resists drying from one to 6. Resists drying from eight to three days. twelve days. 7. Kills rabbits inoculated sub- 7. Kills rabbits inoculated in- cutaneously in from eigh- travenously in from three teen to twenty-four hours. to five days. Rabbits in- oculated subcutaneously remain well or die in from six to ten days. 8. It kills fowls when injected | 8. It does not kill fowls when subcutaneously in small injected subcutaneously quantities. in small quantities. While there are many similarities in the symptomatology of these two diseases, there are pronounced differences in the morbid anatomy and in the specific microorganisms. These facts will render the positive differentiation dependent upon a careful bacteriologic and pathologic examination. In fowl cholera the course of the disease is more rapid than in leu- keemia. Digitized by Microsoft® SWINE ERYSIPELAS 107 REFERENCES. 1. Dawson. Infectious leukaemia. Annual Report of the Bureau of Animal Industry, U.S. Dept. Agric. 1808. 2. Moore. A study of a bacillus obtained from three outbreaks of fowl cholera Bulletin No. 8, U. S. Bureau of Animal Industry. 1894. 3. Moore. Infectious leukaemia in fowls—A bacterial disease frequently mistaken for fowl cholera. Annual Report of the Bureau of Animal [ndustry. 1895-6. : SWINE ERYSIPELAS. §$ 89. Characterization. This disease, peculiar to swine, is determined by a rise of temperature, cerebral disturbances, and pronounced reddening of areas of the skin. It is a disease of adult life. It is stated that pigs are rarely attacked under three months or over three years of age. Lydtin and Schot- telius found some differences in the degree of susceptibility of certain breeds of swine. The common country pig was least susceptible. It is known in France as vouget and in Germany as Rothlauf. $90. History. This disease has been known in Europe for many years. It has not been positively identified in the United States. Smith found a bacterium in rabbits inoculated with the organs of pigs that had died of an undetermined disease in Minnesota, which was either the bacterium of swine ery- sipelas or of mouse septicaemia. The latter organism had been recorded on two previous occasions from pigs in this country. $91. Geographical distribution. Swine erysipelas is an infectious disease which occurs enzootically and in epi- zootics in most of the countries of Europe. Like anthrax, erysipelas is often stationary. It was formerly restricted in Bavaria to the districts along the Danube, and was entirely unknown in southern Bavaria (Kitt). It is stated that the disease tends to become enzootic chiefly in valleys and low- lying plains which have slow-flowing streams, and heavy, damp, clay soil; and that sandy and granite soils are compara- tively free from it. It occurs chiefly during the months of July, August and September, although it appears sporadically during the winter months. Digitized by Microsoft® 108 SWINE ERYSIPELAS $92. Etiology. Loeffler and Schiit7 cae hee pointed out in 1885 that swine erysipelas was fee / WS/ caused by a very slender bacterium 1 to 24 \ ae long and o.3 to 0.4 broad, straight or slightly v N/A curved, ends not rounded and in cultures Ee often appearing in filaments. It is very eee eee cae closely related to the bacterium of mouse y,, jy, of swine septicaemia described by Koch in 1878. In erysipelas. Europe where the bacterium of mouse septicaemia is quite common swine erysipelas prevails. In this country the bac- terium of swine erysipelas has not been positively identified. At three different times an organism resembling it has been isolated from swine. There is much uncertainty concerning the relationship of the bacterium of mouse septicaemia to that of this disease. Smith has suggested that possibly the bac- terilum which has been found in this country may gain viru- lence sufficient to produce epizootics, if such is not already the ‘case. It is exceedingly important that careful search be made for this organism in the outbreaks among swine where the nature of the disease is not clearly determined. House mice and pigeons are susceptible to the bacteria of swine erysipelas. Guinea-pigs and fowls are immune. Rabbits suffer from ery- sipelatous swellings when inoculated subcutaneously in the ear. § 93. Symptoms. It is stated that after a period of in- cubation of at least three days, the disease usually begins sud- denly and violently. The animal refuses food, makes efforts to vomit, has a rise of temperature, manifests severe nervous disturbance, is very weak, torpid and indifferent to its sur- roundings. When approached it tries to hide itself under its bedding.» The hind quarters become weak and paralyzed. Muscular spasms and grinding of teeth are sometimes observed. At first there is constipation, the conjunctiva is of a dark red or brownish-red color, and the eyelids are sometimes swollen. Usually a day or two after the first symptoms develop or, per- haps, from the first attack, reddish spots appear on the thin parts of skin, suchas the region of the navel, lower surface of the chest, perineum, inner surface of the thighs, ears and throat. These spots, which at first are bright red and about Digitized by Microsoft® MORBID ANATOMY sete) the size of a man’s hand, become, later on, dark red or. purple, and soon unite into large irregularly-shaped patches. Asa tule, they are neither painful to the touch or prominent, but sometimes they show a slight inflammatory swelling. The skin of the red spots, especially of the ears, may suffer from an eruption of vesicles and may even slough. The reddening of the skin may be very slight in severe cases, or may appear only immediately before, or even after death. Death takes place usually on the third or fourth day. In the very severe form, the animal may die in twenty-four hours, otherwise the disease requires a week or longer to run its course. Jensen considers that this disease, instead of being uni- form in its clinical aspect, manifests itself in the following forms, which differ from each other by well-marked peculiari- ties. He also maintains that there may sometimes be tran- sitional forms between the respective varieties which he enu- merates. The forms recognized as varieties of this disease but more generally considered as distinct maladies and known by different names are as follows : (1) true erysipelas, (2) swine urticaria, (3) erysipelas without redness of the skin, (4) dif- fuse necrotic erysipelas of the skin, (5) endocarditis of ery- sipelas. Different forms of epizootic erysipelas have also been described by Cornevin, Hess and others. $94. Morbid anatomy. In the ordinary form of epi- zootic erysipelas there is a septicaemic condition without any well marked morbid changes of separate organs. In less acute cases the septicaemia may give way to haemorrhagic and diphtheritic gastro-enteritis considerable swelling of the lym- phatic system, haemorrhagic or parenchymatous nephritis and hepatitis, acute swelling of the spleen, and myositis. The hemorrhagic gastro-enteritis consists at first of excessive inflammation of the mucous membrane of the stomach in the region of the fundus. The mucosa shows a dark- red discoloration, which is partly diffuse and partly in spots. The cells suffer from cloudy swelling and the mucous membrane is covered with a viscid layer of mucus and may have superficial scabs. The intestinal mucous membrane is swollen, especially on the top of the folds and in the neighbor- Digitized by Microsoft® ITO SWINE ERYSIPELAS hood of Peyer’s patches. It is infiltrated with blood and sonietimes shows superficial scabs. Less frequently, circum- scribed parts of the mucosa of the caecum and of the anterior parts of the colon suffer from a diptheritic affection. The solitary follicles and Peyer’s patches appear as prom- inent raised patches. Sometimes they are infiltrated with blood and surrounded by a reddish band. ‘here is ulceration and cicatrisation of the solitary and agminated follicles. The mesenteric glands become more swollen than the other glands of the body, of a dark red color, and show softening. The surface of fresh sections is dun-colored with interspersed dark- red areas. The paraglandular tissue is hyperaemic, and infil- trated with blood. The kidneys are enlarged, the cortex of a grayish-red and the medullary portion of a very dark-red color. Frequently catarrhal nephritis occurs as a complication. The acute swelling of the spleen arises in consequence of an acute hyperaemia with an increase of the cellular constitu- ents of the spleen in which case the organ is enlarged, but not softened as in anthrax. ‘The pulpis of a purple color, moder- ately soft and free from haemorrhages. There is cloudy swelling and enlargement of the liver. The surface of sections has a greyish-brown color, and the acini are widened. The muscles are grey in color, soft, flac- cid, watery, glistening and sometimes they are sprinkled with haemorrhages. They give the general appearance of boiled flesh. The myocardium shows similar spotted changes, and haemorrhages beneath the endocardium. In the abdominal and thoracic cavities and pericardium, there may be found small quantities of an orange-colored, clear fluid, which may be mixed with flaky coagula. Puncti- form hzemorrhages often appear under the serous membranes, especially on the auricles. Many English veterinarians regard the occurence of more or less luxuriant vegetations on the valves of the heart to be so frequent as to be almost diagnostic. It would appear from the literature that this endocarditis is not nearly so common in continental Europe. Severe haemiorr- hages in the brain and in the dorsal and lumbar portions of Digitized by Microsoft® MORBID ANATOMY IIl the spinal cord are rare. The lungs remain unchanged, or at most exhibit a post mortem oedema. By microscopical exami- nation, the specific bacteria are found everywhere in the body, especially in the spleen and kidneys, and to a less extent in the blood. $95. Differential diagnosis. Swine erysipelas is to be differentiated from (1) hog cholera and swine plague. The frequent reddening of the skin in these diseases together with the modified lesions so frequently observed, may cause confu- sion. The bacteriological examination will enable the positive diagnosis to be made. (See hog cholera and swine plague. ) (2) From anthrax which is very rare in swine. Here, too, the bacteriological examination discloses the true nature of the disease. (3) Erythemata due to various dietary causes. The significance of a deep reddening of the skin about the head, abdomen and thighs of pigs is not fully determined. It is clear, however, that such a condition often occurs in the absence, so far as present knowledge goes, of a specific infection. $96. Preventive inoculation. Pasteur’s protective in- oculation is at present the chief prophylactic means employed against epizootic erysipelas. The exact method of preparing the inoculation material has not been published. It is known that Pasteur’s vaccine is obtained by passing the bacteria through several generations of rabbits in succession and then cultivating them in nutritive fluid. The animals inoculated after Pasteur’s method become, according to him, only slightly ill, and acquire immunity to erysipelas. The method of inocula- tion is as follows: the pigs at the age of nine to sixteen weeks are first injected in the subcutaneous connective tissue with a weak vaccine and in ten or twelve days after with a stronger vaccine. The results of the practical application of this method show that it immunizes to a certain extent the inoculated animals. However, the risk of the treatment is said not to be insignificant. It is held that the inoculated pigs infect the healthy and may thus spread the disease. Besides, the adop- tion of this system renders the inoculated animals seriously ill, Digitized by Microsoft® Li? SWINE ERYSIPELAS and according to various European reports, is attended by a mortality of about 4 per cent which it is affirmed exceeds the total loss caused by epizootic erysipelas when allowed to run its course unmolested. Metschnikoff found that the blood of immunized rabbits was antitoxic, and Lorenz maintains that the serum of swine which have recovered from swine erysipelas is also antitoxic, and will produce immunity in other animals. The treatment introduced by Lorenz is to inject the immunizing serum in the proportion of 1 cc. to every 10 kilogrammes of the body weight of the animal. Two days afterward 0.5 to 1.0 cc. of virulent culture is injected, and after twelve days the dose is doubled. Lorenz inoculated 294 pigs; twelve were suffering from swine erysipelas, and of these 6 recovered and 6 died. REFERENCES. 1. BANG. Ueber Rothlauf-Endocarditis bei Schweinen. Deu/sche Zeitschr. f. Thiermed. Bd. XVIII. (1891). S. 27. 2. JENSEN. Die Aetiologie des Nesselfiebers und der diffusen Hautnekrose des Schweines. Deutsche Zeitschr. f. Thiermed. (1892). S2227.9: 3. LOEFFLER. Experimentelle Untersuchungen uber Schweine- Rothlauf. Ardeiten aus d. Katserlichen Gesundheitsamte. Bd. I. (1885). S. 46. 4. LORENZ. Die Schutzimfung gegen Schweinerothlauf mit An- wendung eines aus Blutserum immunisirter Thiere hergestellten Imp- fstoffes. Deutsche Zeitschr. f. Thiermed. Bd. XX. (1894). S. 1. 5. LORENZ. Die Veterinarpolizeiliche Behandlung des Schwein- erothlaufes und die Schutzimfung. Serliner thierarz. Wochen. (1897). p. 574. 6. LORENZ. Schutzimfungen gegen den Rothlauf der Schweine. fbid. (1897). S. 109. 7. Moore. Mouse septiceemia bacilli in a pigs spleen with some observations on their pathogenic properties. Jour. of Comp. Med. and fet. Archives. Vol. XIII. (1892). p. 333. 8. PASTUER ET THUILLIER. La vaccination du rouget des porcs 4 l’aide du virus mortel attenué de cette maladie. Comptes Reudus Acad. des Sciences Vol. XCVII, 1883. p. 1163. g. ScHUtTz. Ueber den Rothlauf der Schweine und die Impfung mit demselben. tissue. (Smith. ) or the lymphatic glands draining them, (2) in the lymphatic glands about the majority of cases the primary lesions are (1) in the lungs head, (3) the intestines and mesenteric glands, and (4) in the portal glands or liver substance itself. Primary lesions some- times occur in the generative organs and udder. It not infrequently happens that the apparent primary lesions occur on the pleura, peritoneum, meninges or synovial membranes while the organs remain free from disease. In such cases the lesions consist of many tubercles varying from one to ten or more millimeters in diameter or of bunches of closely set tubercles which are more or less flattened or irregular Digitized by Microsoft® MORBID ANATOMY 139 in shape owing to their mutual pressure (Fig. 31). Sometimes these tubercles are attached to the serous membrane by a small, tough, fibrous pedicle ; frequently, how- ever, this is absent and the nodules rest bodily upon the membrane. The structure of the tubercle consists, in the beginning, of a few cells surrounding the invad- ing specific organisms. These are soon encased by a zone of epithelioid cells and giant cells which is soon © sur- rounded by an outer layer of round or lym- phoid cells. The central portion becomes necrosed and as the nodule en- larges the central crotic portion becomes Fic. 26. tubes of bovine lungs tached bronchial glands. right and left caudal lobes. b.b., supply ry. and l. ventral lobes. c-c, branches of and bronchial Showing at- a.a., supply Trachea ne- correspondingly large. In cattle there is a strong tendency for the necrotic ws right supernumerary bronchus. c, sup- ply left cephalic lobe. d, branch to azygos lobe. e, trachea. A, leftbronchial lymph gland. B, right bronchial lymph gland. ; C, Lymph gland base of supn. bronchus. D, trated with lime salts gland often between bronchi. The glands and encapsulated (Fig. 4. to D.are often involved. (Smith.) 32). In certain other species a deposit of fibrous tissue in the outer zone of the tubercle has been observed. In the smaller and more susceptible experimental animals such as the guinea pig and rabbit and frequently in swine, the lesions are of a more diffuse nature infiltrating the interstitial tissue with the tuberculous mass and gradually encroaching upon the par- Circumscribed tubercles may also be present. tissue to become infil- enchyma. Digitized by Microsoft® 140 In secondary or ‘generalized tuber- culosis one or more of the organs, omentum, serous membranes, or lym- phatic system may become nore or less thickly sprinkled with minute grey- ish nodules about the size of a millet seed. These tuber- cles are at first al- most the color of mother-of-pearl but later as the central caseous degenera- tion begins they be- come grayish. Giant cells are usu- ally numerous. In studying the lesions in a fatal case of tuberculosis one may find with varying mod ifica- tions one orfmore of the following condi- tions, viz. Gy) the character of the anatomical changes. encysted, caseous or calcareous and dead. TUBERCULOSIS Fic. 27. Dorsal aspect of bovine lungs show. ing position of the posterior mediastinal glands. a, 6, ¢, ¢/., caudal, ventral, cephalic lobes. /. oesophagus. g. muscular pillars of diaphragm- h. posterior aorta. A. left bronchial gland. 7. caudal margin of the ligament of the lung, Mediastinal glands are shown, most of them resting on the oesophagus. The large caudal gland resting on the pillars of the diaphragm ts most frequently diseased and often attains an enormous size. The remaining mediastinal glands are arranged in two sets on the right and left margins of the oesophagus. (Smith. ) The primary lesion may be found in any one of the organs or membranes. Its comparative age is determined by It may be entirely In addition to this primary focus, there may be a succession of tubercles of various ages distributed in one or more organs. (2) The lesions may be restricted to one organ, as the liver in which the primary focus has spread by continuity due Digitized by Microsoft® Plate II. TUBERCULOUS HEART FROM A COW. Digitized by Microsoft® Fic. 29. Pholograph of a portion uf tubercular omentum of a cow, showing the tubercles, natural size. Digitized by Microsoft® MORBID ANATOMY 143 to note that usually the bronchial glands are also involved. When the pleurae are affected the lesions consist of nodules varying in size from that of a millet seed to a large pea, sprinkled more or less thickly on one or both of the visceral or parietal surfaces. These torm the ‘‘pearl disease’’ ( Perlsacht) of the German and the ‘‘grape disease’ of the English writers. If they become confluent, large masses are found. Fic. 30. Photograph of pleura showing small tubercular nodules. Tuberculosis of the thoracic glands is very common and usually accompanies lesions in the lungs ; but often the lungs may be healthy and the glands involved. (See figures for location of glands). The primary lesions may be and often are found in the lymphatic glands about the head. In the abdominal cavity the organs most frequently in- volved are the peritoneum, mesenteric lymph glands, portal lymph glands and liver. The kidneys, spleen, ovaries and uterus are more rarely the seat of tuberculous tumors. Ulcers in the intestine have not been common in the writer’s observation. Tuberculosis of the testis is sometimes found. The udder Digitized by Microsoft® T44 TUBERCULOSIS often becomes the seat of tubercular deposits in cases of gen- eralized tuberculosis. When the primary infection is restricted to a single focus the disease is said to be localized. When the specific bac- teria are spread from the primary lesion through the agency of the lymph and blood streams, sprinkling other organs with the infecting bacteria each of which becomes the starting point for the development of a new tubercle, the disease has become generalized.* It was formerly considered that when the lesions existed in both of the large (abdominal and thoracic) cavities of the body the disease was generalized. It is possible, however, for it to be generalized when the lesions are restricted to the organs of one cavity as the secondary seeding with the bacteria that have escaped froma primary focus through the circulation may be restricted to the cavity in which the first lesion devel- oped. It seems better, therefore, to accept Ostertag’s views and classify local and general tuberculosis in accordance with the nature of the lesions rather than their distribution in the body. The fact is worthy of consideration, that very often cattle killed after reacting to tuberculin do not show extensive dis- tribution of lesions. Frequently animals are killed soon after infection has taken place, in which case the lesions are re- stricted to a single lymphatic gland or other organ. In other cases old lesions of considerable proportion are found as shown in plate II, where the heart muscle was entirely encased ina thick calcareous tubercular deposit. In this case, the animal was in good flesh and killed for beef without a suspicion that it was in any way diseased. S$ 112. Tuberculosis in swine. Channels of infection. It is stated that young animals belonging to the precocious breeds seem to be more liable to tuberculosis than others. In nine cases out of ten the animals are infected by ingestion. The pig easily becomes tuberculous when fed on material rich in tubercle bacteria. If pigs are fed on the refuse from dairies and cheese manufactories in districts where there is much *The Federal meat inspection regulations state, that animals affected with ‘extensive or generalized tuberculosis” are to be condemned. Digitized by Microsoft® TUBERCULOSIS IN SWINE TAS tuberculosis in cattle or on tuberculous viscera they readily be- come infected. Infection through the respiratory tract, while it is certainly possible, seems to be rare. The piggeries where the refuse from butter aud cheese factories is fed and those which adjoin abattoirs supply the majority of animals found On post-mortem to be tuberculous. © 29 Od 8 oe of Om ot o0® 90 sR 9856 0 5855, AO ee STN 3, © OMe GPs CSO PO )%y O N22 (0 09 28D O0 hae Sedge Lo SO OD Ere 0? 88 0 BO Oo © 9(° Logetzoa weds 90° Og 0, (0% Spee? Se Po 9B\0 lo. 29/8 poe s00 Sees t ease nee So0 5 yO DO Sere as DOL ox @ D9, ©/9 GOVE »>¢ veN8e)see te 0 8 ©2505 cN Ce nero O16 ow © els 2 : 2%6 e © dro) NJ Fic. 31. A drawing of a section of a very young tubercle in spleen. ( Thoma). Ostertag has called special attention to this disease as existing among swine in certain parts of northern Denmark and Germany, where there was much tuberculosis in cattle, and where swine were fed upon the slime from creamery sepa- rators. Experiments show the possibilitv of infection by means of the sputum of tuberculous people. In the cases which have come to our notice there is very strong evidence that the swine were infected by being fed upon milk from tuberculous cows. In one of these cases, the tuber- culin test showed that a large number of the cows from which the milk was obtained were affected. Digitized by Microsoft® Fic. 32. Photograph of a section from anterior lobe of a tuberculous lung of a cow, showing rounded tubercular infiltration and calcified centers. (Law.) Dic igitized by Microsoft® TUBERCULOSIS IN SWINE 147 $113. Symptoms. In most cases tuberculosis of the pig is first recognized at the abattoir. Sometimes, however, it causes local and general troubles, which vary according to the organ or system attacked. The following symptoms have been noted. Its localization in the abdominal organs causes the arrest of fattening and the progressive wasting of the subject. The mucous membranes become pale; the hide becomes dirty ; there is usually either constipation or diarrhoea. The animal is in low spirits and remains buried in its straw for entire days ; the corkscrew of its tail is straightened; the abdomen is pendulous and the eyes sunken ; palpation of the abdomen is painful and may reveal more or less voluminous masses, due to the changes in the mesenteric glands. It iscommon to find glandular tumors in the submaxillary region at the level of or at the thoracic inlet. In this form the malady may last several months, but death supervenes rapidly if the lesions are general- ized through the blood stream. Primary pulmonary tuberculosis is very rare but sooner or later lung lesions complicate abdominal tuberculosis, and betray themselves at the outset by a short, dry, abortive cough and by difficult respiration. The cough soon becomes paroxysmal and painful and is often followed by vomiting ; the respiration becomes hurried and gradually pain- ful and more difficult ; wasting is very rapid and death super- venes in a few weeks. The scrofula of swine (glandular tuberculosis) usually shows itself by a puffing up of the face, which a careful exam- ination shows to be lifted up by the subjacent glands, which are enlarged, indurated, still fairly mobile and free from heat or tenderness. The retro-pharyngeal, superior cervical, and sublingual glands usually take part in the lesion, forming a kind of necklace of unequal and knotty tumors, which extend from ear toear, and become larger under the neck between the two of the lower jaw. Similar tumors may be developed at the rami, thoracic inlet, behind the shoulder or in the groin, which, as they increase in size, become harder and more adherent to the neighboring tissues. Sometimes, however, a slight fluctuation is perceptible; the tumor softens, then forms an abscess and Digitized by Microsoft® 148 TUBERCULOSIS IN SWINE discharges a small quantity of thick and grumous pus; but the glandular tumor does not disappear and the opening into the abscess remains for a long time as a fistula. At the same time one may notice swellings of the bones, causing a true tuberculous arthritis when the lesions happen to be situated at the level of an epiphysis. Persistent lame- ness, fistulous wounds suppurating indefinitely, necrosis, caries, etc., are the complications of the lesions of the bone, the development of which is always extremely slow. $114. Morbid anatomy. The manifestations of tuber- culosis in swine, as suggested in the foregoing statement, are exceedingly interesting. Nocard finds the lesions to consist of miliary granulations which rapidly become caseous, as in cattle, but which more rarely contain calcareous salts. Gene- ralization is common, in which case the viscera are thickly sprinkled with gray granulations which are translucent throughout, or opaque in their centers, and quite analogous to those found in tubercular lesions in other animals. As the disease most often results fron: ingestion of the virus, the digestive apparatus and the corresponding lymphatic glands (submaxillary, parotid, pharyngeal, superior cervical, mesenteric, sublumbar, etc.) may be decidedly altered, while the other organs remain practically intact. Lesions of the small intestine and the czecum are common and take the form of ulcers of the mucous membrane, of miliary nodules or of tuberculous infiltrations involving at once the mucous, the muscular, and subserous tissues. The lesions in the liver take the form either of miliary granulations, which are yellow and caseous and scattered in great numbers through the thickness of the organ, or else of rounded nodules which are yellowish white in color, varying in size from that of a pea toa hazel nut, and of a tough consistency. On section they appear some- times to be firm, homogeneous and fibrous ; sometimes soft- ened in the center, but rarely infiltrated with calcareous salts. The peritoneum and the pleura are sometimes the seat of an eruption of fine granulations which remain ina state of miliary nodules. Lesions like those in the liver may exist in the lungs, but generally there is found in these organs an innumerable Digitized by Microsoft® Plate III. TUBERCULOUS SPEBENMOR GEARY: b© SE LEEN Gitized by Microsoft® Digitized by Microsoft® MORBID ANATOMY 149 quantity of minute translucent, gray granulations, caused by generalization through the blood stream, in which case the liver, the spleen, the kidneys, the medulla of the bones, and the mammae are usually infiltrated with similar growths. It is common to find lesions localized in one or several lymphatic glands. The tonsils and the pharyngeal or sub- maxillary glands are the ones most often affected. They be- come voluminous, hard and knotty, as they have undergone a true fibrous transformation and, consequently, difficult to cut. This is shown by the tissues creaking under the cutting in- strument. In section they have the appearance of old fibrous tissue ; here and there small yellow foci are seen of a softer consistency, almost caseous ; sometimes veritable purulent col- lections are found, either encysted or in communication with the exterior. If one submits the caseous or purulent matter to a bacteriological examination, tubercle bacteria are not usually found. The bacterium, however, is present and if this matter is inoculated into the peritoneal cavity or the cellular tissue of guinea pigs it will produce tuberculosis. These chronic glandular lesions, with their very slow pro- gress, have long been looked upon as constituting the scrofula of swine, and to scrofula was also assigned the tuberculous lesions of bones (ribs, vertebrae, articulations, shoulder blades, hip bones, etc.) which are common in pigs, both young and old. The older authors noted that the ancient scrofula was often accompanied by visceral tuberculosis, but they refused to admit the identity and even the relationship of the two affections. The generalization of the disease especially in the mus- cular tissue is reported by several observers. Moulé calls at- tention to this peculiarity of the disease. Stockman shows that while the disease is ordinarily generalized, muscular le- sions may exist in swine in the absence of generalization. Zschokke has called special attention to the localization of tubercular lesions in the head of swine, especially in the nares and brain. Tuberculosis in the horse is rare although a total of many cases has been reported. Bang has collected twenty-nine cases. In Saxony .o8 per cent of the horses (3,500) that were slaugh- Digitized by Microsoft® E50 TUBERCULOSIS tered were tuberculous. In this and most countries there are no reliable statistics respecting the extent of the disease in this species. M’Fadyean has pointed out the fact that ina considerable number of cases of equine tuberculosis, where the horses have been fed milk from tuberculous cows, the morbid anatomy differs but slightly from that in tuberculous cattle. Sheep and other domestic animals are reported to suffer more or less extensively from this disease. All of the so-called tuberculosis in sheep and fowls which I have been able to ex- amine proved not to be tuberculosis but animal parasitisms nodular disease of sheep’’ and ‘‘taeniasis’’ in 6 such as the fowls. $115. Differential diagnosis. Tuberculosis is to be differentiated from actinomycosis, glanders, and various parasit- isms resulting in nodules largely in the walls of the intestine. In cattle the nodules are produced by an Oesophagostoma, in sheep the nodules are caused by Oesophagostoma Columbianum Curtice. In chickensa nodular taeniasis of the intestine is not infrequently mistaken for tuberculosis. Abscesses and necrotic foci due to various agencies must also be distinguished from tubercular lesions. In cases of actinomycosis, the ray fungus can usually be detected on a microscopic examination. Lact. mallet can be found either in cultures or by guinea pig inoculations in cases of glanders, and in parasitic diseases the specific animal parasite can be found if diligently sought.