Ze SO AIAN << 4 | ee Le eyes Lite ZS \ << \ \\ AK \\ SS ~~ tia tite: itil YL Z Oo Ze this tisys g op EE aoe Lhbee Ly Cee egies YHA CH J#@—@@— 00h Z a” SILER CLA ae A es St a tye Lie tj EE LLL CME LZ YY \ \ \\ ZI AY A ~~ A << \\\ \ \ \ A Textbook of Veterinary Pathology A TEXT BOOK OF VETERINARY PATHOLOGY STUDENTS AND PRACTITIONERS BY ho ORIN GISEY. M.iSe- De VS. Pathologist, Kansas City Veterinary College. SECOND EDITION Revised and Enlarged with 194 Illustrations, 5 inserts and one plate. CHICAGO ALEXANDER EGER 1916 Copyrighted at Washington, D. C., by ALEXANDER EGER 1915 PREFACE TO THE SECOND EDITION. This second edition of Veterinary Pathology has been care- fully revised and it is hoped that no errors have crept in. The subject matter has been elongated where it was deemed advis- able. The chapter on Immunity was revised by Dr. J. W. Kal- kus, Pathologist of the Washington State College. New illus- trations have been substituted wherever the subject could be more clearly demonstrated by so doing. To his publisher, Alex. Eger, the author desires to express his appreciation. A. T. KINSLEY. Kansas City, Mo., September, 1915. PREFACE. A knowledge of pathology is essential to practitioners and to students of medicine. The general considerations of pathol- ogy, whether in reference to diseases of the human or diseases of domestic animals, are practically identical. Many textbooks on this subject are available, but they are especially written for the practitioner and student of human medicine, and the illus- trations and examples are all in reference to diseases of the human. Such textbooks have been used by the author for sev- eral years in veterinary classes and it was thought that if the same general pathological principles could be exemplified by cases and illustrations in veterinary medicine, the subject mat- ter would be more readily understood by the veterinary student. This explains the issuance of the present volume. The writer has endeavored to place every phase of pathol- ogy from the veterinarian’s point of view. The entire subject matter has been expressed as far as possible in common every day language, with the hope that all readers will have no trou- ble in grasping the pathologic facts. An extensive glossary has been appended and will be of considerable aid because practi- cally every technical term, with its analysis and definition, will be found therein. The author is greatly indebted to Dr. S. Stewart, Dean of the Kansas City Veterinary College; Dr. D. M. Campbell, edi- tor of The American Journal of Veterinary Medicine; Prof. W. FE. King, Bacteriologist of the Kansas State Agricultural College; Dr. F. J. Hall, Chief of the Food Inspection Department Kan- sas City, Mo., and formerly pathologist of the Medical Depart- ment University of Kansas; Dr. L. Rosenwald, formerly patholo- gist of the Kansas City Veterinary College; Dr..Geo. F. Babb, Milk Inspector of the city of Topeka, Kansas; Dr. D. Cham- plain, editor of The Milk-Man, for suggestions made by them concerning the text matter. Also Dr. R. F. Bourne, physiologist of the Kansas City Veterinary College; Dr. C. D. Folse, City Milk and Meat Inspector of Marshall, Texas, and Mr. Chas. Sals- bery, microscopic laboratory assistant in the Kansas City Vet- erinary College, for their assistance in the preparation of the illustrations. The author consulted various text-books, journals and other publications while preparing the text for which acknowledge- ment is hereby made. If this book supplies the practitioner and the student of veter- inary medicine with clear, concise statements of veterinary pathology, the purpose of the book has been fulfilled. AC ieeke CONTENTS. Preface: to ‘Phe ‘Second: Edition:. ......2.0cc Sees ede cccaus RETA CCH Ay rae n re cere ean Pauw Reed ote Ugh kee WOMMIGIONS A, Wf con Bie. vai ee Se =o WEIS ePID aes le Ce esate diitees Gelli se: Ate EM he tan mama a erets eis ee Ae CHAPTER. EE. General Consideration: of Disease 44. .-225.0 boc soe eee oe Tmhenicede Diseases.” x aia x aren hemes an eetos oath on awit che INCU EIT DISEASES 2 .iyan acd ME ee ae Paplevor \VesetablesParasitess savas eerie ea ne Pky PUOMAV. CLES! wa aso a Net Aree HR ee Sac CHALOMVCeS. yx. ta cil v's Ss SOM cee SR ne ee SOMO MACE LE Sry sre ahaa « Seats, 4 Ree ced area ea tare eee eae NAMIC Pia EASIT CSW a x oar w car hh, wisi et, Seep lee comes eee ae EEO LOZO Veatch casey crags Pe hehe lal o.oo Rae Uae AOTC SIO. PCT EES eh ayaes oes x Ricca Seana ee are Son eC ad eae eS ENTUMGO DOU a:hover nate cael 0 5 Sees eee otea ee rete eats CHAPTER Mt Boaba oh Shot i A were A An ae RO ere RED ENTS SUM a Se boar CHAP RE Ri lal fODMIALONS catenin a's a eee eS al oecavo. areal ease ee te CLAP Aa: Ve Circulatony es DIStin DANCES «5.5 6 icin Sis ws ssp cid age o's tietbearete PR CMOET TA Cees crea aes ork. inte a aaah are here eeenea aS G Pe yiap hots lia Cites spies ocr ayn aiays, ae aieinerd Sie iermisiewe Rea os @Ocdeniae Wropsycor Elydrops. acca c cicero cs «3 soe SGOT DOSIS= 4. wr acrarg A yt ec ore sic sie a oNs cceatona Pa ssetads Us HMO OMS, 19.7. Meee) SS eRe ete whe we Seah Ba. wear Scie tie es sree des Eee eee s chs ot ote ares Miatalaner aera or) 6 Fly Merenitae (ASSLVE), vie aees.cievesteleueid cockeverd etacaye are sees Aly PERCMMIAT CNCUIVE = ame asics corse Ge /erale eae Bates e”s CHAPTER VI. Weahlamiena tone oye yo ais. od ve Se me ae ead ce: s, tisfecb s'als ee oo al CHAPTER VII. IPEOCEESshye cMaSSG MANGES 58 aa. aise elelecl eis «6 sere erin evolsts [RCS NEPA UTION on eye eIO IO C0 OUD OC COD DOE aCe ae i CONTENTS PAGE Wotnd flealing ye trcrcrarse cra aceite cia aie eettens orekews 184 Ey pentrophy sxe eee iat eee ae ee eae 189 EL y per plaSianraomrc\stamow tks ne cencae erer ee tare cen arse 192 Mietaplasia: i:51cc siceter neti ie wiche emtinnewe sonia 215 Gollomd@hances 5 seers attics tierra ae taeenectanele 218 Serousmibatiliratiomirs. 17a us sestcare 3 stercioressus creas aes eer 221 Gly cecenic Anfiltratione ss, cee mrlas ci. ie a ine eae 222 MraticnMnaiilerationaps neas scenic ec et nese eae 224 SER ALO SIS er .ccerer ones ey ic Rle este a ie Seat wees teptaecettaets 225 OSSiMiG aio men yee one yee oars ie ale ous Slee 227 Calcarecous utilication «nie. oss sinc steak ee ee 228 Calcul pacar eck eo Nace tse an Pe) Crace canes Steet ees Ral CGOMEREME NES each stele tate ole cose ie ecete: Sine fale ee 239 Pigmiemtary, iC Manges a. hina: jaroisia’els\onerorehasaloisterere lo oe eee 242 Excessive sPiciientatiotros firs cieni aerosols eestor aeters 244 Absence of, or Diminished Pigmentation <....:.....ss0.-. 250 CHAPTER TX. Necrosis and Death soc isc cracat caw «ck eee sete sk eee ae 251-262 MIN SIG le Ns 1D Catlisns« vaasccte.teccks conoresevstalels 's lovee oh eiers "slevetees 263 Pathologie Deaths sek tert. ofercte sioba ators etwls ole fo che wrclcr=ee 264 CHAPTER: X. MRDTIOL SE NS sk ccharsge g sieia sae Soeptos ik sa Sieas e-einbco eee Gis oe waa 268 ARO Ma pe asec okasor ew do a REE TS mete Netecr ans 279 ANT VeXcOTd allyasee shox pce sclnred scar thsctiat ste Cea kenecic ie ee evac eae aaie ees en eee 284 Ghondronmia: So" ces ete eis coe aaa e is ein es ee ea 285 Winorial sone se alobes mere ets Seepevem ee hes yo ae eate pees Ss 287 QS PEON ar ccs sist anes aptree Creaee © nines ane sae eee ae 290 Glioni a Pe Se. Heese pace eine mee sei eter St eos 291 Odontoma 2.5 cs eee ete es On cha meses ee 291 IN UPONIA 0 s. « sGeters fire 2s a, chet aera eas meee ol Poe NS ore 295 AGO VOM! Ao Sa5.5e.nielate saien herkca atotare spa elele ere renee an 295 ING yO RTA 225. hate, 0) ocatstis alot wren Sietare eseW ass eevee outer ererareicte 298 CONTENTS ill SEU RCLOLATIE NC peace eine aie” Pine ana RD a ly A 300 Rapilotia gota said ate aS Cue RR alee ers ods 321 Kmpryoniceipitmelial MutiOrs. 1. \ocne uses wee: Next to page 71 Insert VI—Explanatory to Plate 1 ........... Next to page 86 PLATE £ Tria TA Lye ais «rs atsrele aoe «8 0 Reet eae ect ware Seiaro wucesteeere 87 A LIST OF THE ILLUSTRATIONS FIGURE PAGE 1—Diagram. of .a\ ypical Gell aire xc ccecccees cscs ioe ce Mea eet 21 2 ES NITMEOSIS eit crevetororehe sie Sooke asia aise ead eas Cae ee Oe 25-206 A-—DRiviSion MOnwNIUCIEUSian dew as as ase etna chicis Che wie eis one ie nines Oe 26 SD VA SHOMMON “Cl ler epe ais aiclelohets eloisisaue oie) Pe ales sie Ge ree Te ee 27 6—Celbinle Restinoy Stage crews oe coe 6 Oe a cok ea ae Soe ee 27 7—Prophase, Showing Division of Centrosome..............00eceeee 27 8—Prophase, Showing Separation of Centrosomes.............00 e005 28 = WMetahasenrc teas acerca heise eoee ale eee ae eae RSA eee 28 10, 11, 12, 13—Indirect Cell Division—Metaphase, Anaphase, Telophase 28-29 ta—Cliated Hpithelium: =U racheai. acids os icets bec oou ooo otee eevee once 30 EGS PETAL ZO. Pot wsteia avalacsliapegvertnessve ere wnS cieue obdeare, mista Raeignet tine estate oe 31 TOS Wed BUCK eye ce areers ts setun ore Miaiena's tye"siein < tiantoe malar ohd MSeo ee wea 47 W—Astracalus Molissimus {(leOCO) a aoe ws ai maie nsec: each eh we vereene 48 18 —“MrichophytONe ONSuUnAaTlS speek cise moto c ete eG eel aie ena rarer ele one 5o TO—Aispercillus uni Satussrc 4. che enuie steersre onee wis ctar'sle © oiele's 0 o.2\ oyspwie # vei svep selene uetealeyene 66 Ba—— MACH AM NCIMM OC OCCUS Ge stare spe nyalersie ioasisle a's ai jere: kehaanas ase «, oleliebareiate siete 67 EVEOpaaiiats (Civawleys Saom go oboabtae aon woceurooedn 204050 cb ao ouomC aot 68 25=—Mrichocepmalis MO ephesStISCUNIS: 1.05 oc ofererslejoteleis ate “haveisiaeiayee eaeirars 69 Bo—Melophagius ‘Owimus) teense ste cocaye wo alps oiteerertemtierae sisieie oro ateieieawheaers 70 B27 = NGASCEOP Mi MAS: PUCUU ate eicge 4-2 (Cutaneous. if i GENERAL CONSIDERATION OF DISEASE. 45 of various animals, especially when the lights are allowed to shine directly into their eyes. Epilepsy has been produced in horses by sudden exposure to intense light. The immediate cause of the effects of exposure to sunlight upon the skin is not known but is thought to be the result of the action of the actinic or chemic rays. The effects of exposure to light upon the eyes is excessive stimulation which produces exhaustion, thus predisposing to, if not directly exciting disease. 3. Electric—Animals are susceptible to the action of elec- tricity. Horses are especially susceptible to its influences. Some authorities have claimed that a direct current of 500 volts, 100 amperes, is sufficient to kill a horse, and an alternating current of 160 volts is destructive to medium sized dogs. A 1,200 pound horse was electrocuted when he stepped upon a wire carrying 220 volts of 220 amperes. Contact with electricity may be the result of lightning, and charged electric wires, or rails. Horses and cattle frequently are struck by lightning while in pastures, and animals used in cities are occasionally accidentally brought in contact with elec- tric currents. Depending upon the amount of electrical current, the results may be a slight singeing of hair, burning, or lacera- tion of tissues in general. Carcasses of animals destroyed by electrical currents have also been observed in which no lesions could be found. On examination of carcasses of animals dead of lightning stroke, there is usually more or less singeing of the hair, hyperemia and hemorrhages along the course of the current and a persistent fluidity of the blood. 4. Chemic.—Chemic substances capable of producing disease are very common and may have their origin from the mineral, veg- etable or animal kingdom, and are inorganic or organic. It is probable that practically all chemic substances may, under cer- tian conditions, be injurious to the tissues of the various animals. Some chemicals are always injurious, others may become injur- ious by chemic change induced by the tissue juices. Those chemicals capable of producing deleterious effects in the animal tissues are poisons. (Poisons are substances which when taken internally or applied externally alter health or destroy life with- out acting mechanically or reproducing themselves). According to their modes of action, poisons have been classi- fied as follows: 1. Corrosive poisons, (caustics and irritants). The action of this group varies from the production of a simple hyperemia to necrosis. The most common agents are mercury, arsenic, sodium and potassium hydroxide and the mineral acids. — n* i ee ie path a Fold-out Placeholder This fold-out is being digitized, and will be inserte future date. he nae eek 46 VETERINARY PATHOLOGY. 2. Parenchymatous poisons. This group produces tissue degeneration, especially parenchymatous and fatty degenera- tions. The most common parenchymatous poisons are the tox- ins, endo-toxins, ptomains, leucomains, phosphorous and silver. 3. Hemic poisons. These act principally upon the red blood corpuscles and may inhibit combination of hemoglobin and oxygen, and cause disintegration of the cells and even produce thrombosis. The principal agents that combine with hemoglobin are carbon monoxide, sulphuretted hydrogen, hydrocyanic acid, the chlorates, and mercury. 4. Nerve and Cardiac poisons, These may produce paraly- sis by over-stimulation of nerve centers, or they may produce variation in the rate and force of the heart beat. Narcotics, such as atropine and solanin are types of neurotoxic poisons. Potas- sium salts depress the rate and increase the force of the heart action. A poisonous drug acts in various ways, depending upon the form of the drug, size of dose and method of administration. The following are the more common inorganic poisons :— arsenic, mercury, sodium, potassium, lead, copper, chlorine, and the various oxides, salts, acids and bases formed from them. Many organic compounds are responsible for poisoning in animals, as phenol, iodoform, picric acid, hydrocyanic acid. In fact most of the medicinal organic compounds are poisonous in large doses. There are many plants that are responsible for extensive losses of live stock in all parts of the United States, Canada and Mexico, and are most common in range districts. Colorado and Montana have had losses aggregating $200,000.00 annually, in live stock, from plant poisoning. The following table gives the common and botanical names of plants that most frequently produce poisoning in animals. (See insert No. 1.) These plants are not all poisonous during their entire devel- opment. The cocklebur is most poisonous in the earlier stage of development, that is, at the time the cotyledons come through the soil and for two or three days after the plant is up. Lupines are harmful principally while the seeds are maturing. Larkspurs are harmful only until the flowers appear. Dry seasons are usu- ally most favorable to the formation of poisonous principles in plants. Ergot develops most extensively during the wet sea- sons. Second growth or stunted kaffir corn and sorghum plants are more likely to be injurious than first growth or well devel- oped plants. GENERAL CONSIDERATION OF DISEASE. 47 Poisonous plants usually have some noxious properties as odor, taste, or appearance that protects them from consumption by animals. Poisoning usually occurs in animals that are hungry or are not accustomed to the location, or at least are not familiar with the plants that abound there. Animals in districts where poisonous plants are found are usually familiar with the dis- agreeable properties of them and let them alone or the animals may become accustomed to the injurious principles of the plant, Fig. 16.—Red Buckeye (Aesculus Pavia). that is, develop a tolerance similar to immunity to infective diseases. In their vital activities microphytes (bacteria, yeast and moulds) and microzoa (protozoa) produce chemic substances that are extremely poisonous to animals. Thus saphrophytic bacteria produce ptomains in putrefying flesh. Fermented, musty or mouldy hay contains injurious substances that produce indigestion in the horse and ox. The specific products of micro- parasites will be discussed under the topic of vital or infective causes of disease. : 48 VETERINARY PATHOLOGY. Bees, wasps, scorpions, ants and other animal organisms liberate poisonous chemic substances (zootoxins) which, when introduced into the animal body cause marked disturbances. Poisonous snakes secrete and liberate injurious chemic sub- stances. The poisonous principle, zootoxin or venom is pro- duced by glandular tissue, and is liberated through canals or Hig. 17.—Loeo (Astragalus Mollissimus). grooves in their fangs. The exact chemic composition of venom has not been determined but it is not the same in the different venomous snakes. Noguchi has classified the principle action of venom as follows :— : 1. Instantaneous production of thrombi. Crotalus (rattle- snake), 2. Neurotoxic action. (Cobra.) GENERAL CONSIDERATION OF DISEASE. 49 3. Produce capillary ruptures and hemorrhage. Crotalus (rattlesnake). 4, Produce hemolysis, Crotalus (rattlesnake). 5. Produce general cytolysis. Crotalus (rattlesnake), and viper berus (adder). The following is the toxicity estimate of venom per kilogram body weight :— Cobra venom .00009 gram lethal dose for horse intravenously. Cobra venom .0005 gram lethal dose for dog subcutanously. Rattlesnake .005 gram lethal dose for rabbit subcutanously. Viper .0001 gram lethal dose for rabbit intravenously. Retrograde metamorphosis in the tissues of the animal body frequently results in the production of leucomains which, when absorbed, are extremely poisonous and cause marked disturb- ances. Over action of muscular tissue may cause the produc- tion of leucomains, thus horses that are overworked, although their food and water are first-class and their digestion is good, are occasionally affected with a severe diarrhoea caused by the action of leucomains. Parasitic or Infectious ——During the last quarter of a century pathology has received an impulse by the knowledge of micro- parasites acquired during this time. Although parasitism has been known since the dawn of the 19th century, the importance of microparasites has been recognized only since bacteriology became a science. Parasitism is an evolutionary condition. It is the result of a long continued struggle, and the survival of the fittest, during which there is a necessary adaptation to constantly changing en- vironmental conditions. Parasitic causes of disease include rep- resentatives of both the plant and animal kingdom. Parasitic plants (Phytoparasites) are practically all microscopic in size and are termed microphytes. Pathogenic plants are all fungi and the following scheme gives their position in the plant kingdom: VEGETABLE PARASITES. KINGDOM BRANCH CLASS ORDER FAMILY GENUS SPECIES Plant Thallophyta Efyphomycetes <2... soec en Gece Mucidineae Oospora Porrigines (Achorion schoenleini 2. Plant Thallophyta Hyphomycetes Plecascineae Aspergillaceae Aspergillus Fumigatus 3. Plant Thallophyta Hyphomycetes Plecascineae Aspergillaceae Aspergillus Niger 4. Plant Thallophyta Ascomycetes Protoascineae Saccharomy- Saccharomyces Farciminosus cetaceae PeePlan tei nalmopimy ta: Semi ZOMmy.cCetes assesses eels one ccieieleleys lelers ciate Actinomyces 30VB 6. Plant Thallophyta Schizomycetes ......:-:sssesegeveeeeeeeees Bacterium Tuberculosis, ete 50 VETERINARY PATHOLOGY. Hyphomycetes (Moulds). Hyphomycetes or moulds are non-chlorophyllic plants. Structurally they are composed of mycelial threads from which upright reproductive organs may be formed. They are usually multicellular and reproduce by spores. They require preformed foods and thrive best in the absence of light. Oospora porrigines (Achorion Schoenleini) is the organ- ism that causes favus. These organisms have mycelia with ) \ ICT IasS No dQ ) Y) Se y % Z OA SY, | ‘Ss s (| 3 \\ 3 1 \ Fig. 18.—Trichophyton ‘onsurans. showing mycelium and spore like bodies. hyphae, the latter may be branched and terminate in bulbous ends. The mycelium is later converted into oval spore-like bodies. Favus is occasionally observed in dogs and cats, more rarely in horses and fowls. The disease is characterized by dry scales which are brown, yellow or even white upon the surface and vary from white to sulphur yellow in their deeper layers. The areas involved are usually not more than Y% to 34 inch in diameter, and are usually devoid of hair. The lesion may occur on the head, especially on the forehead, cheeks or ears, and on the abdomen, or outer surface of the hind legs. GENERAL CONSIDERATION OF DISEASE. 51 Sporotrichium Audouin (Trichophyton Tonsurans) is the fungus that causes ring-worm (tinea tonsurans). This fungus is found in the lesion and is probably strictly parasitic. Structur- ally it is composed of a simple or branched mycelium which may become broken up as a thread of ovoid spores. The spores may also appear in groups in the hair follicles. The disease becomes evident because of the presence of small circular hairless patches which are covered by grayish crusts or scales. As the disease progresses the central portion of the lesion becomes normal and the peripheral tissue becomes involved. This condition has been observed in the horse and ox; other domestic animals rarely become affected. Qoree Fig. 19.—Aspergillus Fumigatus. Aspergillus, Fumigatus is responsible for an occasional out- break of pulmonary mycosis (Pneumo-mycosis, Aspergillosis) in birds. This fungus is of common occurence in nature. Struc- turally the fungus consists of a segmented mycelium which may branch dichotomously and from which upright stems termed hyphae may originate. These hyphae may be segmented and terminate in club-like heads. A tuft of hair-like projections (sterigmata) develops from the hypha head and on the distal end of each hair there is a spore bearing organ (conidium). The 52 VETERINARY PATHOLOGY. entire hyphae head with its spore bearing organs is included in a capsule the rupture of which is necessary for the distribution of the spores. The spores of Aspergillus are present in large numbers in hay, straw, barn-yard manure, etc., and they main- tain their virility in the dormant state for a considerable length of time. The source of infection is contaminated food, water or air. The principal lesions are located in the trachae, bronchi, lung and air cells of bones. The disease is characterized by a fibri- nopurulent inflammation of the mucous membranes of the trachea and bronchi and abscess formation in the lung. Aspergillus Niger is probably responsible for some cases of ear canker in dogs. Saccharomyces. (Yeast). Saccharomyces are the budding fungi. The classification of this group, the yeast plants, is as yet incomplete, their general biologic characteristics not being well known. A few varieties, however, have been studied, one of which, Saccharomyces Cere- visiae, is of considerable economic importance to the brewers. Yeasts are ovoid or spherical single celled non-chlorophyllic plants that reproduce by budding. Structurally the yeast cell has a cell body composed of protoplasm and a double cell mem- brane the latter composed of condensed protoplasm. The cell body may contain vacuoles, granules or foreign substances. Reproduction, which is by budding or gemmation, occurs at one or both ends of the yeast cell and even in some cases from the side of the cell. Budding begins by the appearance of small tubercles or buds which develop until a considerable size is attained. The daughter cell may remain associated with the mother cell or it may become detached and then pass through a similar cycle. Under certain conditions the yeast plant may develop into filamentous threads and in other instances may produce spores. Saccharomyces was, for a considerable time, associated as an etiologic factor in the production of carcinoma. It is prob- able that the “carcinoma bodies” (dense refractile oval bodies) are yeast cells but it is quite evident that they have no etiologic significance in carcinomas. Dermatitis in the human is, in some instances, of a saccharo- mycetic origin and no doubt some of the resistant cases of der- matitis in domestic animals have a similar cause. GENERAL CONSIDERATION OF DISEASE. 53 The principal pathogenic saccharomyces that concerns the veterinarian is the Saccharomyces farciminosus, which has been described by Rivolta as the Cryptococcus farciminosus. This yeast is the cause of epizootic lymphangitis, a disease which affects equines and primarily involves the cutaneous lymphoid tissue. The disease is prevalent or has prevailed in many localities in the United States, and in the Philippines, as well as, in India, Japan, China, South Africa, England and Ireland. The principal lesions are located in the lymphoid tissue which becomes tumefied and inflamed and in which the lymph sinuses are found to be engorged with coagulated lymph Fig. 20.—Weast (Saccharomyces farciminosus). and pus. The lymphoid tissue later undergoes central liquefying necrosis and this is followed by the formation of pustules or ulcers. After the discharge of the pus the ulcer gradually heals and the related tissue becomes indurated. In a few cases lesions have been observed in the liver and spleen. Two other pathogenic fungi that have not been satisfactorily classified are the Actinomyces bovis and the Botryomyces ascoformans. These are the causative agent of Actinomycosis and Botryomycosis respectively. These micro-organisms as well] as the diseases they produce will be discussed later, 54 VETERINARY PATHOLOGY. Schizomycetes (Bacteria). As will be noted by the foregoing scheme, bacteria are classed among the lowest groups of plants. Each bacterium is a single cell and contains no chlorophyll. The science of bacteriology is of recent development, because early investigators were compelled to use comparatively crude microscopes and because they were not familiar with the condi- tions required for bacterial growth. The development of bacter- iology was coincident with the discussion pro and con of the theory of “spontaneous generation.” This theory was disproved +4} ‘ % ey 33 » oe, "6 , 4 52 ee Seee Secs % f+ %, weongre® ve og ee ; £8 1 2 3 4 5 Fig. 21.—Showing different forms of Cocci. 1. Micrococcus. 4. Tetrads. 2. Streptoccus. 5. Sarcina. 3. Diplococcus. ; by Pasteur about 1865, whose classical experiments also aided in establishing bacteriology as a science. (It is possible that bio- chemists may produce life, (animate objects), by synthesis of inanimate substances which will only represent the achieve- ments of ultratechnical scientists and will not signify that spon- taneous generation occurs in nature). Thirty or forty years ago the study of bacteria was looked upon as a fad by the majority of the people. However, the practical application of bacteriologic knowledge in medicine, sanitation, the various arts and agriculture, has caused bacteriology to assume its present important position as one of the principal biologic sciences. Bacteria are found everywhere that animals or higher plants have grown. They are practically omnipresent. Bacteria are single celled plants, each individual possessing a cell body and a cell membrane. The cell body is principally GENERAL CONSIDERATION OF DISEASE. 55 composed of protoplasm, which may be homogeneous or granu- lar. In some instances non-protoplasmic particles may be pres- ent. Chromatin, the essential nuclear material, is regularly dis- tributed throughout the entire cell body and no doubt functions the same as a nucleus. Granules that are intensely stained with methylene blue occur in the body of some bacteria, but their significance is not known. The cell bodies of some bacteria contain starch granules while those of others contain sulphur - ts yeu oe, Fig 23.—Various forms of Spirilla. granules. The cell membrane is of a protoplasmic nature and is probably formed by condensation of the protoplasmic cell body, whereas cellulose constitutes the cell membrane of the cells of higher plants. Some species possess organs of locomo- tion called flagella, which are delicate protoplasmic projec- tions of the cell body or cell:membrane. Some bacteria, per- haps all, possess a capsule which appears as a gelatinous sub- stance and is probably derived from the cell membrane. The th MRS, Fig. 24.—Flagellate bacteria of various forms cell body is the essential structure and presides over metabol- ism, reproduction and practically all other functions. Circu- latory, nervous and excretory organs are obviously not required in such simple forms of life. The cell membrane protects the cell body. Bacteria are very small, one eight millionth part of a cubic inch has been estimated as the least mass capable of being de- tected with the naked human eye. This space will contain about 2,000,000 ordinary bacteria. The dimensions of bacteria are ex- pressed in the term micron which is the unit of microscopical measurement. (A micron is 1/25,000 of an inch and is desig- nated by the Greek letter “Mu’”.) The Bacterium tuberculosis averages about 2.5 microns in length and about .5 microns in 56 VETERINARY PATHOLOGY. width, i. e., 1,000 tuberculosis organisms placed end to end would make one inch in length or it would take 50,000 of these bacteria placed side by side to make a linear inch. Some spher- ical bacteria are less than one) micron inediameter,, 6 2.) the pyogenic micrococci average .8 of a micron in diameter. Different individuals of the same species may vary considerably in size, thus the Bacterium anthracis may vary from four to ten microns in length. Some diseases are probably the result of infection with micro-organisms that are so small they can- not be detected by the use of present day microscopes and they also pass through the best known germ-proof filters. These in- fectious agents are designated as invisible or ultra-microscopic and may be present in a “filterable virus.” a» ©& 223 ~~ = Fig. 25.—Bacteria, showing capsule. Morphologically bacteria are very simple. Three principal types of bacteria are recognized according to their form, viz: the rod shaped (Bacilli), spherical (Cocci), and the spirals, (Spirilla). Another type, characterized by branching forms, (Chlamydo-bacteria), has a few representatives but their classi- fication as bacteria has been questioned. The representatives of each of the three principal groups, Bacilli, Cocci and Spirilla, are constant in their morphology so long as the environ- ments remain the same, i. e., the progeny of bacilli are bacilli, etc. Again, each individual is constant in its form, increase in size being the only change that occurs. Frequently, however, unfavorable conditions may cause pleomorphism among indi- vidual organisms. Perhaps the best accepted morphologic classification of bac- teria is as follows :— 1. Coccaceae, spherical shaped bacteria. 2. Bacteriaceae, rod or cylindrical shaped bacteria. 3. Spirillaceae, spiral shaped bacteria. GENERAL CONSIDERATION OF DISEASE. Sis 4. Chlamydo-bacteriaceae, branching or irregular torms of bacteria. According to their biologic characteristics, bacteria may be classified as follows :— Aerobic or anaerobic. Chromogenic or non-chromogenic. Zymogenic or non-zymogenic. Saprogenic or non-saprogenic. Photogenic or non-photogenic. Thermogenic or non-thermogenic. Saphrophytie or non-saphrophytic. Parasitic or non-parasitic. Pathogenic or non-pathogenic. Pyogenic or non-pyogenic, etc. Bacteria, like other living things, grow and reproduce under favorable conditions. They grow until they attain a certain size then they divide, i. e., a cell divides into two equal halves, each half representing an individual bacterium which in turn grows and ultimately divides into two equal halves, etc., thus bacteria grow and multiply. The rate of growth and division is com- paratively rapid. The Bacillus subtilis, under favorable con- ditions may pass through the life cycles incident to attaining its growth and dividing, thus doubling in number, every 30 min- utes. Barber has found that Bacillus coli communis, under optimum conditions may divide by fission, in seventeen min- utes. Beginning with one bacterium, it has been estimated that if division occurred once per hour and continued for three days, the progeny would weigh 7,417 tons. Some other cells, notably the undifferentiated cell in the animal embryo, may divide as rapidly as bacteria, but they do not become developed, and so far as known, there are no other cells that complete the entire cycle of growth and reproduction in so short a time. This method of reproduction is called fission. Fission occurs in the three principal forms of bacteria. Among the Bacteriaceae and Spirallaceae, the division takes place in the transverse diameter, while the Coccaceae may divide in one, two or three planes. Bacteria grow and divide by fission as long as favorable conditions are supplied. When the environments are unfavor- able the organisms cease growing and do not increase 1n num- ber. Some species produce spores when conditions become unfavorable for further growth and fission. Bacterial spores, generally characterized by being small, highly refractive oval shaped bodies, are more condensed than the original cell body protoplasm. Spore formation is first indicated by the appearance 58 VETERINARY PATHOLOGY. of small granules in the protoplasm of the parent cell. These granules collect and ultimately coalesce thus forming the spore. The spore may form in the center of the bacterium or near one end. After the spore is formed the remainder of the bacterial body becomes disintegrated. Spores are much more resistant to external injurious influences than are bacteria. ‘The resist- ance of spores is due to the fact that they contain less water than bacteria, moreover they enjoy the protection of a thick covering or cell wall. Spores are inactive, i. e., they remain dor- mant until placed in favorable media and under favorable con- ditions when they germinate and develop as the vegetative form. One bacterium produces only one spore which in turn produces Fig. 26.—Bacteria, showing fission. only one bacterium and hence spore formation is not a means of multiplication, but is rather a natural means of preservation or continuation of the species. Those species of bacteria in which no spores are formed usually have a greater resistance to injurious influences than do the vegetative forms of the species which are capable of producing spores. | Bacterial food requirements are quite variable. Some types of bacteria require preformed organic compounds and others appear to have the power of synthesizing the simplest com- pounds and available elements into new compounds upon which they subsist. Until recently it was supposed that synthesis was confined to chlorophyllaceous plants but some species of bac- teria are now known to possess the power of building complex compounds from simple materials, e. g., the nitrifying bacteria. Parasitic bacteria and most saprophytic bacteria as a rule re- quire preformed organic compounds for their food. Some soil GENERAL CONSIDERATION OF DISEASE. 59 bacteria and many water bacteria appear to live and thrive on simple inorganic substances. In fact most bacteria are capable of adapting themselves to an inorganic food medium. Food sub- stances must be in a dilute form in order that bacteria may subsist upon them. This is probably because of the osmotic differences of bacteria and their surroundings. Some chemic substances, usually considered as destructive to bacteria, when sufficiently diluted are food for certain bacteria, thus the Bacillus pantotropus produces formalin and then uses it for food. It is said that Bacillus pantotropus may live and thrive in a 1 to 15,000 solution of formalin. Bacteria as a rule require food media of neutral or slightly alkaline reaction, (as shown by Pig. 27.—Showing spore formation. litmus paper) though some grow readily in acid media. While foods are required in small quantities only for each bacterium, yet because of their rapid multiplication and the resulting enorm- ous numbers, the quantity of food substances consumed by them becomes of considerable importance. Most foods of bacteria like those of animals or higher plants, must undergo modification preparatory to assimilation. As previously stated, bacteria do not possess a digestive tube, neither do they have the power of enveloping particles of food as do some protozoa. Bacterial digestion is an extracellular process, 1. e., the bacterium digests food substances that are outside of its own body. This process is the same as the digestion in higher animals, the digestive tube in the latter being outside of the body tissues. Bacterial digestion is the result of activity of ferments produced by the body protoplasm and in this respect is comparable with equine digestion which 60 VETERINARY PATHOLOGY. is the result of activity of ferments produced by protoplasm of the salivary, gastric, pancreatic cells, etc. Some bacterial digestive ferments are very similar if not identical to the digestive ferments of higher animals. Digested foods or food substances in solution pass into the bacterial body by osmosis. Bacterial respiration is a simple process. The exchange of gas is probably accomplished by means of the transfusion of fluids containing the respiratory gas. Bacteria may vary in their oxygen requirement. Aerobic bacteria are those that require oxygen as a respiratory gas. Some bacteria will not develop Fig. 28 —Bacterium Anthracis, in the absence of free oxygen, obligatory aerobes. Although it was originally supposed that all forms of life required free oxygen this is now known to be an erroneous idea. Thus, the anaerobic bacteria require the absence of free oxygen; and some organisms,—obligatory anaerobes—require the absolute absence of uncombined oxygen. Other bacteria, facultative aerobes or anaerobes, are not so selective in their oxygen requirements, e. g., some are capable of immediate adaptation to a medium containing free oxygen. It is probable that anaerobic bacteria require oxygen as a respiratory gas but the oxygen is obtained from oxygen compounds that are decomposed by these bacteria, the oxygen probably being consumed while in the nascent state. Moisture, temperature and light are other physical condi- tions that affect bacterial development. A very few bacteria GENERAL CONSIDERATION OF DISEASE. 61 will remain active in substances containing less than twenty per cent of water. The optimum conditions relative to moisture, requires the presence of about 80 per cent of water. This fact is observed in the preparation of dried food stuffs and is the essen- tial reason why dessicants favor wound healing or retard infec- tion. The temperature range of the various bacteria is wide. Some bacteria live and thrive at a temperature near the boiling point, others at a freezing temperature. Pathogenic bacteria, in general, require the temperature of their host. The chicken has a very high normal temperature (107° to 108° F.), and this Fig. 29.—Bacillus Tetanus. may explain its immunity to practically all the diseases that affect other domestic animals. All bacteria require the absence of light for their best development. By adaptation some have become capable of growing and thriving in daylight. The effects of bacterial growth and the products evolved during bacterial growth vary according to the micro-organism in question and its environment. Heat and light are two forms of energy produced by bacterial activity. The heating observed in manure piles, alfalfa, hay and various grains in the stack is thought to be the result of bacterial action. In the above sub- stances, the contained moisture favors the growth of bacteria and the growth of zymogenic bacteria is always dependent upon chemic changes in which complex compounds are reduced to 62 VETERINARY PATHOLOGY. simpler ones. Such chemical changes are accompanied by the evolution of heat. In all fermentation, in which the substances acted upon are converted into simple compounds, heat is liber- ated. Light or phosphorescence may be produced by bacteria. The phosphorescence of decayed wood, ocean water, flesh, etc., may accompany the growth of light producing bacteria. Light is a form of energy and bacterial light or phosphorescence is the result of the conversion of some other form of energy usually kinetic energy, into ether vibrations or light. The production of heat and light are of little importance in comparison with other bacterial products and activities. Pigments of various kinds are produced by several different species of bacteria. ‘These pigments may be an excretion or a secretion or they may possibly represent synthetic extracellular products or enzymotic by-products. The importance of bac- terial pigments is largely confined to the discolorization of food substances. Thus the Micrococcus roseus, Bacillus prodigiosus, and Bacillus erythrogenes, produce a red pigment in milk. The red pigment in the milk is sometimes mistaken for bloody milk. Other bacteria produce a variety of pigmentation in food sub- stances. These pigments are variable in composition and solu- bility. Generally speaking the bacterial pigments are not injurious when consumed. Practically all pigment producing bacteria are aerobic. The principal action of most bacteria is the result of the activity of ferments or enzyms produced by the bacterial pro- toplasm. Some of these bacterial ferments may produce their specific activity while inside the bacterial body, others bring about specific changes after being secreted and eliminated from the bacterial body. The end products resulting from the activity of bacterial enzyms or ferments are variable and depend upon the specific enzym or ferment also on the composition of the substances acted upon. Acids or alkalies represent the end products of many of the bacterial decompositions. Carbohy- drates are usually converted ultimately into an acid, carbon dioxide and water. Protein substances may be converted into different simpler introgenous compounds or into carbon dioxide, water and ammonia by the activity of many different bacteria. Putrefaction is a bacterial decomposition of nitrogenous sub- stances and occurs in the absence of air. The end products of putrefaction are extremely variable; hydrogen, carbon dioxide, nitrogen, hydrogen sulphid, and ammonia, are some of the com- mon gases that escape from a putrefying carcass; amido com- se enw" Sebagre : ‘ ~—Fe Gres m o-earet Uses: rose Wane ey ts dewdece a tap LBere Pernt * ~ “Ee soi aiotare has +~K peed fi -k > be « nA > ew a Oley L. 4 s di mint a oa Sa pte mee : ieee: Seana om bee ed = ——— ~ 2 ’ ams%os oan pac nee oat Pema paeatee ete e pete fo! aad rae a To ne ; “3 ao ae, i : =e oa ee ora ee : shales eats ptt ale eres Sores > sae Nie ene OE ay Se 4 ; F Rts Seer: = Seren Ee” have orem 1s ay INSERT II. The following are the more important bacteria, the animals susceptible to their action and the disease each produces: Baccillus aerogenes capsulatus ........+.0++ eeeeeeeees + +s Gaseous OMPHVSEMA: anccicciweclee cccccecensestscisecvcescccese All Animas TActllusealveline ow chet eeiz ernie cle are, clolarelofeiecole(orere sielel ele fiaretetels) v1aj0 MOULD LOO mere ei eu stalais]s'ale ers niminlehecvie’siorers (ele/ale) si cherelew slain je siolela(siasiekSCOS Bacillus anthracis symtomatici ............-......-....Black leg VatnnteeseesCatue Bacillus Bronchicanis culealealcaienleipielcisiaies siete cicivaicie im CaninceGistemiper avnlelaavevcierele/eie nie e1eceleivinloleje/sie\e'ste'sluieleievsieieiaisjeisie lt Ope) Baciilua-coli communis... isle Giec cries esielelaicied eter COLMA, Nepnritig, enteritis: cicaics sci dteeit ssa suitor coat n Almanimals Bacillus enteritidis yh ae Me. og RELL ELS Social lana ae RL SRO Mea EE ee DONA ReD Bacillus necrophorus .....-Necrotic, stomatitis, foot rot -..--Calves, sheep Hogs, dog aecee Malignant O€CdeMa .......eccccccrccccccccsccccrccceccevcceecesAll animals ..-...S5uppuration aisle e°o:0' ois) 6/0 fale elaxeshielalie (aloraisteletelareierayael eLrLAIn Ole eee. Tetanus see ceeeteccccccccccee All animals ....Anthrax Slajeiaistalsleldelereaveleleisyeioteare AIM Na 1s weer ese eeseseesesresesse seers eeeeseons ey eee a or ry ee eee ewe eee tee eee eee ee Caeeses ee aeee ee ee eee ee oedema maligni .... pyocyaneus tetani Bacillus Bacillus Bacillus Se ee ee ey Ce were ene sree eee eseerer ene seseee we meee et ewe bee ee reer reser seses Bacterium Bacterium Bacterium anthracis astheniae dysenteriae ... eeeee eevee er ey seeee oe ....Asthenia Dysentery Bacterium mallei ... a a a a) ..-.Glanders Sara. eiotsleteNascustetets) ert oletslalaiere sleratel evelere exeloivl elle cietets(orelsferorres UG ULeR eralntesoleiersiersl vvereieleie'siclere-siareleyelerelstrrelsletosletefataverniont OUI Sieteeiciere SOOALVCR Of Preisz ....escecccceceseeescee souceseeese- Caseous lymph adenitis Areiatonel ovaretcs orate. alsvelavetaraiscays aiesealarenr ial eeen aie OWE pulorum eWhite diarrhoea accccorcacccvcccccrsacesecsosr -sseeeeeres Chickens septicaemia hemorrhagicae ...Pasteurelloses tele felceniespaisiewtelonesicre SILOS septicaemia hemorrhagicae .... ... Pasteurelloses . weeoeeeeses Guinea pigs septicaemia hemorrhagicae .... ...Pasteurelloses See cists once ktADDite septicaemia hemorrhagicae . ...Pasteurelloses (Wildseuche) weeeeeeeseee Wild animals septicaemia hemorrhagicae . ..-Pasteurelloses (Pneumoenteritis) nelclelalalsicisleeNMeeD septicaemia hemorrhagicae . ..-Pasteurelloses (Infectious .pneumonia) aici rine eee COLTS septicaemia hemorrhagicae ...Psateurelloses (Pleuro-pneumonfa) cadieiniclowielete treioslarerer CALVES. septicaemia hemorrhagicae ...Pasteurelloses (White Scours) ocecese sCalves septicaemia hemorrhagicae .................Pasteurelloses (Barbone) eos on ed diepoteremresds WILalO septicaemia hemorrhagicae ..-+ ....+.+e+esee Pasteurelloses (Infectious pneumonia) «eee.» Horses septicaemia hemorrhagicae (bovisepticus)..... Pasteurelloses (Hemorrhagic septicaemfa) DjeresielsisieiaOCLle erysipélatis suis .......-sesscces.ceeeseeseeeeebrysipelas aielicaveleienaters .atevsteueusiers¥ei etene le ..-Hogs Bacterium tuberculosis oe Glave sleeps eee CU DERCULOSIS ..- All animals Gladothinl xe Caml sce clerasiereic sieia cle elelele: sits siclele oils clslelelensis hisielete OUD DULACION nics wivie’=! Voisierslels ...- Dogs Micrococus caprtnus cee cte LAKOSIS .. Goats Spirochaetae anserin® .........eeeeeeeees ...Geese Staphyloccoccus pyogenes albus........-+-...+-++-.---.+-Suppuration ........ ...All animals Staphyloccoccus PpyOSeNeS AUTEUS ....+-- +++ waeereereece -Suppuration ........ .-- All animals Staphyloccoccus pyogenes CitreuS ...--+++++ eeeeeeeeeeees Suppuration .. All animals Streptoccoccus pyogenes (many varieties). ...........+- Suppuration .. All animals The following bacteria may be the cause of the following diseases. Bacillus abortivus vaccarum .........0+5+ eeoeeeseeeseeInfectious abortion Bacterium bronchiolitidis vitulf ........0++ e++e+eeeeeee/Caseous pneumonia ..,.......+.- sesee:: Bacterium sanguinarium wlolbbsialelstarevelde AILS CELOUB IU INUL Gy ol orelayotatels lleva tite eceur celetazelsioversnersa (ex Bacterium swine plague coecececcseeswine plague eiaecolere Micrococcus abortivus equi ...........+++++ eeeeceeceseeednfection abortion Micrococcus mastitidis OVIS .......qe-seeee eeeeceoeee ee Mastitis Micrococcus tetragenous ..:.......eee eee ee cece eeeeeeses Umbilical suppuration Bacterium Bacterium Bacterium Bacterlum Bacterium Bacterium Bacterium Bacterium Bacterium Bacterium Bacterium Bacterium Bacterium Bacterium Cec eescagcaes os aceveeesasseeerre® wee we eee eer ene ee ey eC wee ee eee meme eet ar reeset ee eteeestag s tees eccene wee tee rere meee reessoseet rset et tetos wee e ween reese es erene eee e cere eseeee eC ee ee weer e eee eee oe toe Co eee e eee i eC ee Pe ee oe ee eC ry see eeee ee were ere reer ees e~ Ae ee eee ese er ere stores eet ore ee i rr? wee cece ee © tee ee rete oe eee Ce meer eee reer ese veserressssreesersesessseeeesereeseees? eee weer ee sere seers eens eee eer es coer eeeees ee ee ee ee eee eer ee eee cee eee sees oe eeeceee SC a i i cy aetie dae Atle atersisttiaier OATULE aie eidhereleiere «LOOMIS Drajeteieisiote LORS SiateielelaieleeeLORSee Selecteer OVINES eicishriaissis MO OLV.eS citersieverele CAULle PROO eC CeO OsCeCr a at) ire OO Cc iO) Se Ce ee ee ee a a ay Ce ca Se ee ee Streptococcus agalactia .......sceceee cere cece eee reer eMAStitis cece eee eee ee eee eee eens cece ees see Streptococcus equi ....--. ee eeseeee eee setts cee eeeceeces (OChUITZ) Stranwlesis accel ree cree ouolecere easy aiverveeve aver oceiererarss OUST aS Al manele natn cINLECtiGUALVAEINItIB: cj ccrsiel. cris coiuccm nal ticletieeie eels elsible sletrere AU Ue Streptococcus vaginalis vaccarum pamela ee Se ORDER SPOROZOA, Reproduce by 2 A el no flagella, no cillia. -OTOZOA, nicellular animal organ- S, asexual, reproduce fission, sporulation. or INFUSORIA, Possess cilia or flagella, reproduce by fission and budding. HIRUNDINEA, Slightly flattened on dor- sal and ventral surface, sucker at each end. ~ ‘of ring like sege- simple head and usually eversible ted pharynx, etraight nentary canal, well de- loped nervous system. CLASS COCCIDIA. SARCOSPORIDIA. FLAGELLATA. HYPOTRICHA. GNATHOBDELLA. INSERT Ii. FAMILY GENUS SPECIES PSOROSPERMIDAE. Coccidium oviforme Coccidium cuniculi Coccidium avium Sarcocystis Miescher! Sarcocystis tenella SARCOSPORIDAE. Balbiania gigantea CERCOMONIDAE. Lamblia intestinalis Monocercomonas hepatica Trypanosoma equiperdum. eens Evanai, Trypanosoma equinum. TRYPANOSOMATIDAE. Trypanosoma Brucei. GNATHOBDELLIDEA, Hirudo medicinalis Hirudo troctina. Hirudo decora Hirudo Tagala. Haemopis sanguisuga. HOST PART INFESTED Rabbits, G. pigs and manLiver and intestine. Rabbit. Lieberkuhn’s glands and intestine. Fowls. Liver and intestine Pig. Muscles, Horse, ox, sheep, and pig. Muscles. Ox, sheep and dog. Connective tissue. Sheep and dog. Intestine. Pigeons, Liver, Horse. Blood. Horse. Blood. Horse. Blood, Horse. Blood, Man and horse. Skin. Man and horse. Skin. Man and horse. Skin. Man and animals. Horse ange respiratory tract and tntes- ne, (WW neal We a Va NS, ya Vass Te a ui a a a AGC ‘= 7 » Se MON Mes TD Hay Mien" ah i Puy hie? realty ee Nery OP Py rs t, By Vann asin ng pore MED el & c8) GENERAL CONSIDERATION OF DISEASE. 63 pounds, pepton, skatol and indol represent aromatic compounds ; ptomains probably represent one of the most important putre- factive products. Ptomains are basic chemic substances pro- duced by decomposition of nitrogenous compounds. They are usually formed outside the body, although they may be formed by putrefaction of the contents of the intestine. Ptomain pois- oning is usually the result of consumption of foods contaminated with ptomains, although it may result from the absorption of ptomains formed within the intestine. Sufhcient ptomains may also be absorbed from necrotic tissue to produce injurious effects. The chemic substances produced by pathogenic bacteria are probably of more importance than any other bacterial com- pounds. Although they have been extensively studied the com- position of most of these compounds is still unknown. Three groups of pathogenic bacterial products deserve mention, they are (1) bacterial toxins, (2) endotoxins and (3) bacterial pro- teids. 1. Bacterial toxins are soluble, synthetical, poisonous, chemic substances elaborated by the bacterial protoplasm and liberated into the surrounding media. The chemic composi- tion of bacterial toxins is unknown. ‘They are very similar in many respects to enzyms. They are specific, 1. e., a given organism always produces a definite toxin. According to Ehrlich bacterial toxins are composed of two combining groups, one the haptophore which combines with the receptors, of the animal cells and forms a medium through which the other group, toxophore, acts. They are the principal product in some infec- tion, e. g., tetanus. (Infection is the invasion into a living body of pathogenic micro-parasites, and the sum total of the disturb- ance produced by their presence in the body.) During infection the body attempts to neutralize bacterial toxins by the produc- tion of a substance termed an antitoxin. 2. Endotoxins are poisonous chemic products formed and retained within the bacterial body. They become liberated only when the bacteria are destroyed and distintegrated. Although the chemistry of endotoxins is not known, they are probably constant in composition and produce specific symptoms in in- fected animals. ‘The animal body does not produce antibodies that neutralize endotoxins, but opsonins are produced in the tissues of animals immunized to endotoxins. Endotoxins are the principal injurious substances produced by pyogenic cocci, Bacterium tuberculosis, the organisms causing glanders, pneu- monia, and other specific infections. 64 VETERINARY PATHOLOGY. 3. Bacterial proteids are insoluble nitrogenous constituents of the bacteria cell protoplasm. They are not well understood. (See insert No. 2.) ANIMAL PARASITES. The animal parasites, capable of producing disease in an- imals, are quite numerous and represent the following branches of the animal kingdom :—protozoa, helminthes, and arthropoda. Fig. 30.—Piroplasma Bigeminum in the red blyod corpuscles. Protozoa. Protozoa are microscopic single celled animals. They are very simple in structure, being composed of a mass of proto- plasm with or without a cell membrane. ‘The cell membrane, when present, consists of concentrated protoplasm The pro- tozoa having a cell membrane are constant in shape, as the Try- panosoma Evansi, and those not possessing a cell membrane vary in shape from a sphere to an irregular flat mass and are capable of changing their shape whenever occasion demands. Protozoa are larger than bacteria. Protozoa require food similar to the foods of higher animals. Particles of food may be inclosed or incorporated by them pre- paratory to digestion. Digestion is accomplished by means of ferments elaborated and secreted by the protozoa. The digested foods pass by osmosis into the protozoa, the undigested portion being extruded by rearrangement of the cell protoplasm. Res- piration takes place by exchange of gases through the surface protoplasm of the protozoa. They reproduce by fission, budding, conjugation or sporulation. Protozoa are universally distributed. They all require con- siderable moisture. In fact most of them live either in fresh or salt water. A few only are parasitic. GENERAL CONSIDERATION OF DISEASE. 65 The specific action of pathogenic protozoa in the produc- tion of disease is not understood. Some may have a mechanical effect only but the evidence concerning others indicates that most of them produce an injurious chemic substance. Helminthes. This branch of the animal kingdom contains many species that are parasitic. Structurally, animal parasites are much simpler than the closely related nonparasitic animals. The sim- plicity of parasites is a result of adaptation to environments in which essential structures of the nonparasitic type, useless to the Fig. 31.—Trypanosoma Evansi in a bloodsmear from a horse affected with surra. parasitic type, atrophy because of disuse. The parasitic hel- minthes are of the simplest structure, their nervous, digestive and respiratory systems being very rudimentary. Their food is obtained from their host. Some animal para- sites, as the tapeworm (Taenia) absorb digested food stuff from the intestine of their host, others subsist upon the host’s blood, (Uncinaria), and till others consume tissue juices and lymph, (Trichina spiralis). The reproduction of helminthes is accom- plished by means of ova, or by the production of living larvae. The life history or cycle of helminthes is very interesting. In some cases the organism is parasitic in different animals during the different stages of its life cycle; for instance the Taenia cras- sicolilis inhabits the liver of the rat during its cystic stage and the intestine of the cat during the adult stage. Helminthes produce injury to their host by consuming food, by sucking blood and by liberating injurious chemic substances. 66 VETERINARY PATHOLOGY. Arthropoda. This branch includes many parasitic representatives, as flies and mosquitoes (diptera), fleas (siphonaptera) lice (hemip- Fig. 382.—Sarcocystis Miescheri. Drawing made with Camera lucida. 1. Cross section sareocyst, muscle cell enclosing carcocyst ruptured. 2. Cross section of heart muscle cell. 3. Fibrous connective tissue. tera), itch mites and ticks (acarina). The entire order, siphon- aptera and hemiptera, most of the order acarina, and many rep- resentatives of the order diptera are parasitic. Of the parasitic arthropoda some are temporary and some are permanent para- oe ; t j 1 ry , F Hy a i v hy i. by ly i f an x ‘ie mi ca , i | ‘ i ry A *. 1! . ‘ j i? ‘ ‘? rt nA ; e . 1A ) nt 4, a My fe Pe, ye we va { { (age) aye b) ae ‘ fad a, ; ‘ i 2 12 «9 f . ; ‘ i Yo ar 41 eo ’ { Pit : ed we a al : e f { im haw i . a A .. Ly I i" i] . q t : 7 : ba ar iY if & o, a th ji a 7 fe ACY, ' ; i! y : it . a at : y :, { wy |e | A x Y ue @ : ig va i t 2 “ i f a Ta hh he) Ue F J = q 1 ’ j i I 2 4 UJ 7 1 LE : ms) F Ls it g a mn i ioe qi { » 7 if ij * at } - é a vee bres an ‘a _ “a J i ae a Wyss : : i v7 A =! 7 - 4 my ‘ , } i _ Ms A 1 oan le Vy : , i. i i. ig tak j i rae Us a t a _ iY t : ' i , é we « . , Bui tade: A hit if in ¥ ? V2. ’ ij | ff ; y i ; : bi nq » ee a : ua OP a Me RG 60g a * 7 : xO x Han os my: 2 ie i , hb, ATS ne © AS eo Wie. ; ; eae way a 9 i , 1 iu a i : : : 7 fi C7 | i v ‘ j f PK en) ae ee a ean p PA wir 7 i i sie rains i ras * { Os - y TT ¥ ‘ery : i ; 7 A An ‘ ¥ ; : ; ity ee 4 \' ii } vy lM i- i a Le : _* i rea au ( ; : =. : a ee a) 4 Aa Tes naga, BRANCH CLASS OLDER FAMILY GEN | US SPECIES HOST PART INFESTED « } x | bess perinatte mi Man I st; sticercus: nests Taenia solfum : cus: Cellulosae, of Pig.) : Bess: : ; sticercus mien Taenia perfoliata Berta Of GE) Horse h : Taenia mamiliana Horse inteating TAENIIDAE, Taenia Plicata _ Horse joeeeuee Head always has four] ‘aenia denticulata Ox Intestine suckers between which is} Taenia expansa Ox and she Duodenus CESTODA, found a depression or a| Taenia fimbriata Sheep as ee ea i Ribbon shaped, séegment-] proboscis. Segments usu- have no fixation apparatus] ally have their gential op- ’ have no digestion apparatus | enings on margin, Taenia marginata & ; D y ae ne Seinis eautegrss tonceotta of umn anigie el Bees ; . Dog, w , ante conte BosuEea cerebralis in spinal co:d and brat Peg re coh eee 8 Dog and wolf ‘PLATYHELMINTHES, (Cyst; Echinococcus polym Small intestine Flat worms, nearly afl Taenia cucusherina polymorphous, of herbivore and omnivora.) hermaphodites, (Cyst; (1) Cryptocystis trichodectis of Trichodectes latus.) Taenia aes (2) Cryptocystis pulecides ee Pulex serraticeps.) A : , 0 . ‘ ous . ae a ag (Cyst, cysticercugs ovis sheep.) : Small Intestine et Cpe * nonsegment- ' Bothriscephalus latus Man, dog, cat Intestine é aa ed, have Mow! gad gn = n> anus, have one or two Distoma hepaticum Herbi i ey suckers on ventral surface. OrIarOMIpas Distoma lanceolatum Sheep, ox, goat, pin, eae, Gall cece dog All have two suckers, an] Distoma Americanum Sheep and ox aie anterior and ventral. Amphistoma cervi Ruminants — omen 3s Paragonimus Westermanil Man, dog, pig and cat Lungs J] sok ACANTHOCEPHALA, SE Slender worms, complete ECHINORYNCHIDAE, Echinorhynchus gigas Pig Small intestine 9g digestive canal, are found Found in digestive canal Pee in all tissues of domestic of vertebrates. | animals except bone, 2 J $36 Perce are loey, resemble ese nd megalocephalus Solipeds Small Intestine - gk r th is} 48caris bovis Ox Intestine > earth worms, mou Ascaris ovia - bog © surrounded by three Ips. “ascarisuilla % Breey OA & Bip poe: found in small in-} 4 ecaris marginata Dog Intestine rs a9 i Ascaris mystax Cat Intestine oat Y exe Golndeate body, tai | Oxyuris curvula Horse * Posterior bowel Z 523 pointed, mouth’ nude, ! Oxvuris mastigodes Horse Posterior bowel fd $3 if stomach large. : KES Strongylus Arnfeldi Solipeds Bronchi and lungs Poa Strongylus micrurus Bovines Bronchi and lungs ako Strongylus pulmonaris Calt Bronchi mae Strongylus filaria Sheep, goat, camel, deer Bronchi and lungs Strongylus rufescens Sheen, goat and deer Bronchi NEMATHELMINTHES, pS ae | Strongyius Osteragl or Room aaibie ound worms, nonseg- : Strongylus contortus Sheep, goat Abomasum and duodenum mented, sexes separate. Rene i outs Strongylus filicollis Sheep and goat Small-intestine and abomasum! or fated os pola ha oF Strongylus gigas . Horse, ox, dog and man Kidneys and arinary organs ee * oseophagus Strongylus vasorum Dog Heart BLE: Selerastoma equinum Horse, ox, dog and man. Intestine ‘ Sclerastoma tetracanthum Solipeds Large intestine Sclerastome hypostomum Sheep and goat Large intestine Syngamus trachesis ; are and chickens bet pg Wigtivey: aiid liver St rus dentatus g ' egion 0 q tinciuarla trigonocephala pas ane. fox : Snell intestine Uncinaria cernua eep and goa Sma n Uneinaria radiatus Bovines Small intestine NEMATODA, : Slender worms, complete] TRICHOTRACHELIDAE, ; Caecum digestive canal, are found| Body slender in, “anterior | Ticpoccphaius erenatus Ge jelinep yaa ORE |. Caen ating in all tissues of domestic] portion, eniarged poster-| niichcccphalus depressiusculus Dog Gaecum animals except bone. oy cor cpr rd tel Trichina spiralis Pig Muscles terminal, all live in intes- : oF tine. 7 Peritoneal and plural cavities {llosa Horse Te peer Ox and deer SPOlEGH SHED * a sutmnanaey Biter Filaria immitis Dog weies re: re pulmonary e Spiroptera megastoma Horse ght stomac AE, Stomach ry Rinresd like body, ola dbp Sete Ry . Horse Flexor tendons asd cervical igus GE a ah Blaatic ie Ox, sh a goat Oesophageal. wall phagus small. Spiroptera scutata x, sheep and go Spiroptera. sanguinolenta Dog paces of. stomach, gullet and Pig, dog and cat Gastric mucosa GNATHOSTOMIDAE, Gnathostomum chelracanthus Head distinct, -oviparous. ms et - ui [Aba wR RY 5 ALD Heed “1 Alsenian ; ! Bh paged Kia, CAA Ce Alea a J SNHEMATSKNN, wy aD HY AL sh hee) bn Hea th “Nah it nie fet ree ie PANES "wildy A ¥ SRA Phe aed Bc hs le Ao a vitevns iw ne : stig oA Va! Use 9 Phat o mee ER. Sen a aie . Shi Ain ey fw eM si wu wee : whiten: tas AY ine ak (Nea ae Sete aa A) ethene ae y ie Y i ; ns ee ea a 1 OM . i \ ; END RSC RE fs Ta aU ; th ce hi PRS cy Pat j Yi Wr | fa new ¥ ae ‘ j Y GENERAL CONSIDERATION OF DISEASE. 67 sites, and with one or two exceptions they are all external para- sites. The structural peculiarities that differentiate arthropoda from the other branches of the animal kingdom are their jointed ap- pendages, segmented body, and bilateral symmetry. The parasitic arthropoda obtain their food from their hosts. Some of them consume epidermal scales and hair, e. g., the horse louse (@richodectes' pilosus) and: feathers, ¢«. ¢., the Fig. 33.—Taenia Echinococcus. Niles & Neuman. a. Adult tapeworm. After Neuman. b. Part of hog’s liver showing cystic form. chicken louse (Menopon pallidum) others abstract blood, e. g., the hog louse (Hematopinus suis), itch mite (Sarcoptes scabei variety canis), and still others may consume tissue cells other than blood cells as epithelium. Reproduction of arthropoda is about the same as it is in helminthes. Disease resulting from infestation of arthropoda is due primarily to irritation induced mechanically or by chemic pro- ducts of the parasites, secondarily to loss of blood. Extension of Disease.—By extension of disease is meant the invasion and affection of adjacent structures and even remote x 68 VETERINARY PATHOLOGY. tissues of the body. Some diseases are necessarily local, 1. e., the cause is not capable of being transferred to adjacent or re- mote structures, e. g., ocular filariosis. Other diseases are in their earlier stages local, but later the cause may be transferred to some other part and produce secondary diseased foci or Fig. 34.—Oxyuris Curvula, after Niles. a. Adult worm. b. Cephalic extremity. ec. Caudal area. metastases, e. g., tuberculosis. The extension of disease may be produced as follows: First, by the cause of the disease passing along the natural channels and establishing secondary diseased foci, thus, Bray reports that calves become affected with necrotic gastritis and enteritis when allowed to swallow the necrotic tissue during an attack of necrotic stomatitis. Second, by the spread of the cause into adjacent tissues, e. g.: Extension in like tissue, as in muscular tissue, is termed contin- GENERAL CONSIDERATION OF DISEASE. 69 uity and is exemplified in psorospermosis, while extension from one tissue to another of a different type, as from muscular to connective tissues, is called contiguity and is evidenced in acti- nomycosis. Third, by the lymph and lymphatic nodes, e. g. tuberculosis. Fourth, by the blood stream in which case the mestastases will be in the lungs, liver, or kidney,—e. g., anthrax. The incorporation of microbian agencies by leucocytes is frequently the means by which infection is extended, in fact it is probable that the leucocytes are the principal factor in lymph and blood extension of infective processes in the body. Fifth, by passing along the nerve fibres as in rabies. Termination of Disease.—Termination is the ending or outcome of the condition or existing disease. Disease terminates as follows: Recovery.—Disease terminates in re- i ly ‘ i Sy Ve . } 5 he) i i, iar Fig. 35.—Trichocephalus covery when the body tissues are effectually Depressiusculus q of a Dog, after Railliet. repaired and all structures have assumed their normal function. Diseases resulting from irritating or non-nutritious foods are corrected by expulsion or neutraliza- tion of the causative agent either by vomition, purgation or chemical union and by repair of the injured tissues, after which normal functioning continues. Tissue afflicted with mechanical injuries as wounds, recover when the destroyed portions have been replaced and the normal function has been resumed. Dis- locations terminate in recovery when the dislocations have been reduced and the parts assume their normal function. A horse recovers from pneumonia when the inflammatory exudate has been removed from the alveolar spaces and all injured tissues have been repaired and the normal functioning has been re-established. In general, recovery is the result of the comple- tion of the protective and reparative processes of the various tissues of the animal body. Partial recovery.—tlf{ the normal functioning is not assumed after a disease has run its course, recovery is said to be incom- plete or partial. Partial recovery is observed in old animals or in those that have been depleted because of complications or previous disease. Some diseases are essentially destructive and their influence in the tissue results in incomplete repair, as in 70 VETERINARY PATHOLOGY. tuberculosis, glanders, dourine, bovine contagious pleuro-pneu- monia, etc. Injuries and acute inflammation of the parieties of Fig. 36.—Melophagus Ovinus, after Niles. a Dorsal view of adult. d. Terminal segmant of leg. b. Ventral view of adult. e. Shell of pupa. ec. Mouth parts enlarged, f. > Pupa, hollow organs frequently terminate in the formation of cicatrical tissue thus contracting the lumen of these organs. This is com- mon in injuries of the oesophagus, intestine, trachea, and ure- thra. Adhesions succeeding pericarditis, pleuritis, and periton- itis are examples of partial recovery. i Ass i iit ph & ‘ : , ' \ \ F, - ‘ so ; Wess ’ : I hihi, «0 | Mm ve J Vibes a tf +i by r itary uy i ; Hep d mI ld od Pam “tT rs 7 WY lt 7 y i] 1 f i ° J , ‘ the j Wea) - of pa¥s i ! < i r 4 vf , , f > ” ‘ a 4 ; iy ’ , ; ~ ARTHROPODA £ 4 a g - 3 2 & Fi a 9 3 5 vo a Fy 3 - 5 - ° how! s = 3 2 2 3 J 5 vo 5 z ” INSECTA (HEXAPGDA), Air breathers, when adult have three pairs of legs, and distinct head, thorax and abdomen. ARACHNIDA Air breathers with caphal- othorax and abdomen, have when adult four pairs of legs. Those here included are oviparous. ORDER DIPTERA Have two wings, two hal- teres, sucking mouth parts, and complete metamor- Phosis, includes flies and mosquitoes, HEMIPTERA Wings often absent, when present one pair thick and one pair thin., Suckjng mouth parts, incomplete metamorphosis, and include the blood sucking lice. MALLOPHAGA Wingles lice with sucking mouth parts, and incom- plete metamorphosis, SIPHONAPTERA Wingless fieas with suck- ing mouth parts, and com- plete metamorphosis. ACARINA Usually short thick, non- articulated bodies, possess larva usual- sexes gsepa- camerostoma, ly hexapodal, rate. UATULIDA. Taternal arasite, elongat- ed, vermiform, annulated FAMILY Have soft probosis adapt- ed for suction, stylet of an- MUSCIDAE tennae plumose to the end. Broad and slightly flat- tened body, large head, muscular wings, larva car nivarous, are oviparous. STOMOXIDAE Closely resembles the mus- cidae. TABANIDAB | SIMULIIDAE . Thick body, bulging tho- Trax, «segs strong. HIPPOBOSCIDAE Flat body, head notched into thorax, legs strong, pupiparous, OESTRIADAB Body usually hairy, large wings, proboscis very small, oviparous. CULICIDAE Have tong slendor abdo- men, wings fringed with hairs, antennae plumose in males, oviparous. PEDICULIDAE Blood suckers, proboscis formed of upper and lower lips and armed with small spines, contains protrusile tube or sucker, oviparous. RISCINIDAE Not blood suckers, have long masticatory apparatus with which they eat epi- dermic yroductions, ovi- parous, PULICIDAE Very agile, brown ovat bodies, compressed latter- ly, biting mouth parts in larval stage. IXODIDAE Large globular blood-suck- ers, oviparous, have undi- vided hypostome. Argasidae~ GAMASIDAE Rostrum arranged for pricking or sucking, have no eyes. TROMBIDIIDAE Soft, hairy, bright colored, rostrom a conical sucker. SARCOPTIDAE i Smalhest of the acarina, body soft, white or red- dish, eyes absent, ovipar- ous or ovoviviparous. DEMODECIDAE Very small, vermiform, hairless, cephalothorax and abdomen distinct, legs short, oviparous. LINGUATULIDAE Body segmented, com- pressed dorso-ventrally, crenelated. GENUS SPECIES Musca domestica Musca vomitoria Sarcophaga carnaria Stomoxys calcitrang. Hematobia serrata Campsomyia macellaria Tabanus atratus Tabanus lineola Glossina morsitans Simulium pecuarum Mellophagus ovinus Hippobosca equina Gastrophilus equi Gastrophilus hemorrhoidalig Hypoderma lineata Oestrus ovis Culex equinus Culex pipiens Anapholeg punctipennis Stegomia fasciata Hematopinus macrocephalus Hematopinus eurysternus Hematopinus vituli Hematopinus piliferus Hematopinus irritans Hematopinus stenopsis Hematopinus ovis Trichodectes pilosus Trichdédectes scalaris Trichodectes spaerocephalus Trichodectes latus Tricodectesclimax Tricodectes subrostratus Pulex irritans Pulex serraticeps Pulex avium Margaropous annulaiug Boophilus Australis Amblyomma Americanum Dermacentor electus Ornithodoros Megnini Ixodes ricinus Argas miniatus Dermanyssus gallinae Trombidium holosericeum Leptus irritans scabei-var, equi. scabei var. ovis. scabei var, suls. scabei var. canis. mutans Sarcoptes Sarcoptes Sarcoptes Sarcoptes Sarcoptes Psoroptes communis var. equl Psorptes communis var. bovis. Psoroptes communis var. ovis. Symbiotes scabei var. equi. Symbiotes scabei varfi bovis. Symbiotes scabei var. ovis. Symbiotes auricularum var. Symbiotes auricularis. var. felis Demodex folliculorum yar. equi. Demodex folliculorum var. bovis. Demodex folliculorum var. cani, Demodex folliculorum var, sus, Linguatula taenloides cani, HOS? Not generally parasitic Animals Animals Animals Animals Animals Animals Animals Animals Animals Sheep Animals Animals Animals Sheep Horse Ox Sheep og Goat Cat x Sporting dogs Horse, ox, sheep and dog Sporting dogs Fowls Fow!ls Animals’ ; Man and animals Wounds Skin Skin Skin Skin Skin Skin around perina¢um M. M. of stomach M. M. of stomach and intestine Dorsal cutis and subcutis Sinuses of heud Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Skin Nasal cavities GENERAL CONSIDERATION OF DISEASE. C IME Bp Gastrophilus Equi, after Niles. a. Adult female. b. Adult female. e. Young larvae. d. Full grown larvae, e. Eggs cemented to hair. f. Egg shell showing lifting of operculum. gs. Adult male. h. Terminal segments of male. i. Terminal segments of female. Fig. 38.—Oestrus Ovis. a. Adult female. ec. Dorsal view of larva. b. Adult male, after Rily. d. Ventral view of larva, after Rily and Niles, VETERINARY PATHOLOGY. NI bo Ny BIT ge ; ke, afi . = AERA, ry oS 7 b iw? SSS / ek aN SA8 A | a NUR APES TH TR aa | 43 ahaha ON Fig 39.—Culex Pungens, after Howard. a. Female. b. Male, ec. Larva. GENERAL CONSIDERATION OF DISEASE. 73 Death—Disease may terminate in the cessation of all func- tions, i, e. death. The more important specific modes of death are as follows: Fig. 40.—Distoma Hepaticum., a. Intestines. b. Oral sucker. e. Ventral sucker. d. Uterus. 1. Syncope, or heart failure, a result of paralysis of cardiac nerves or muscles, rupture of heart walls or complete obstruc- Fig. 41.—Echinorhynchus Gigas, after Niles. a. Cephalic extremity showing hooks. b. Worm with portion of mucous membrane of intestine attached. tion to emerging vessels of the heart. Nerve paralysis may be the result of poisonous products derived from infectious agen- cies, or chemic poisons derived from katabolism, or hemorrhagic extravasates. » 74 VETERINARY PATHOLOGY. 2. Apnoea, or respiratory failure. This may be the result of paralysis of respiratory nerves or muscles, spasms of respiratory muscles, rupture of diaphragm, or occlusion of the respiratory tubes. 3. Apoplexy, or hemorrhage into the brain tissue. This is probably the specific cause of death in apoplectiform anthrax. 4. Hemorrhage, especially rapid loss of large quantities of blood. Any of the above may act independently in producing death, but are probably more frequently complicated one with another. CHAR iE Re Eble IMMUNITY. DEFINITION. IMPORTANCE. VAURIUE: TIMES: Inherited, (Natural). Definition. Examples. Cause. Ceil Action, (Metchnikoff & Sternberg). Chemic Substance, (Ehrlich & Buchner). ACQUIRED, (Artificial). Definition. Examples. Varieties. Active. Definition. Varieties, (Toxic), (Opsonic), (Bacterial) Etiology. 2 Recovery from attack of disease. Inoculation with virus. Inoculation with vaccine. Inoculation with bacterin. (noculation with toxin. Inoculation simultaneously with virus and antibody. Passive. Definition. Etiology. Inoculation with antibody. THEORIES. Exhaustion. Retention. Phagocytosis. Humoral. Ehrlich’s Lateral Chain Theory. Immunity literally means proof against disease, i. e., it is the name of the condition that onibiles an animal to resist the action of pathogenic micre-organisms, or to be unaffected by their products. Immunity is only a relative term, the condition is not absolute and permanent neither is it constant and con- tinuous. Whenever an animal is unable to adjust itself to its environments it becomes susceptible to the effects of the causa- tive agents of diseases, i. e., its immunity, at least acquired immunity, is suspended. The term immunity is ordinarily used in reference to infec- tive diseases, i. e. those diseases resulting from the invasion of microparasites; although it may be used in designating the resistance to the action of zootoxin, such as snake venom, and possibly also of the poisonous substances ejected by centipedes 7b 76 VETERINARY PATHOLOGY. and scorpions, as well as the phytotoxins, such as ricin, abrin, crotin, and robin. Immunity, more than any other problem, directly concerns the medical profession and indirectly the international commer- Fig. 42.—Hematopinus phalarges ovis, after Niles. a Adult. b. Egg cemented to hair. cial welfare. It was a laboratory fad of the pathologists until they demonstrated to the practitioners that it was feasible to produce immunity in man and animals. Veterinarians have now Fig. 43.—Pulex Serraticeps, after Tugzer. IMMUNITY. Td almost tuniversaily accepted the proposition and have at their command the means by which they can immunize animals against the ravages of some of the fatal infective diseases to which they are susceptible. The increased confidence of the people is in turn enabling scientists to investigate new phases of the subject. Although immunization has been known and made use of more or less for centuries as vaccination against Fig. 44.—Margarapus Annulatus, female. Fig. 45.—Margarapus Annulatus, male. Fig. 46.—Margarapus Annulatus, Fig. 47.—Margarapus Annulatus, Larva. female laying eg#ss. smallpox by the Chinese before the Christian era, yet the essen- tial physiologic, chemic or pathologic basis for immunity is still unknown. Immunity may be natural (inherited) or artificial (acquired). Natural immunity is an inherited property possessed by or- ganisms (animals). The horse has a natural immunity to hog cholera, the ox to glanders and the hog to tick fever. The concise and exact cause of natural immunity is unknown. It is probably the result of cellular activity in the immune animal, an activity the nature of which is not understood. Some inves- tigators, Metchnikoff in particular, attribute natural immunity to phagocytosis (cellular hypothesis), others maintain that insus- 78 VETERINARY PATHOLOGY. ceptibility to disease is a result of the antagonistic action of the body fluids (humoral hypothesis). Ehrlich’s lateral chain the- ory assumes that the cells of immune animals are not capable of combining with the toxins of bacteria, i. e., they have no receptor molecules and hence those animals are not receptive, they are immune. Whether we accept the cellular hypothesis, the humoral hypothesis, or Ehrlich’s lateral chain theory, the fact remains that natural 1mmunity is a characteristic or prop- erty of parental origin that is transmitted to the offspring and is present at the time of birth. Natural immunity may be the result of an acquired toler- ance due to natural selection and heredity. There is a marked variation in susceptibility and resistance in individuals of a given species. A continuous or repeated exposure of susceptible ani- mals to a given pathogenic microparasite will result either in destruction of those animals or the production of an immunity, i. e., those individuals most resistant will survive and their resistance will become more and more fixed and will finally be transmitted to the offspring and hence be a natural immunity. Thus all native Cubans are practically immune to yellow fever because at the time yellow fever was first introduced into Cuba the least resistant individuals died of the malady, the most resistant individuals survived and lived in the presence of the diseases almost continually after yellow fever was introduced into Cuba (It was not eliminated until after the Spanish-Amer- ican war). Consequently the Cubans for several generations developed in the midst of yellow fever and only the resistant individuals survived. This resistance finally became so firm that it was transmitted to their offspring and was then a nat- ural immunity. The resistance possessed by dogs to most diseases is ex- plained in a similar way to the Cubans’ resistance to yellow fever. Thus the dog has descended from the jackal and the wolf, two types of animals that have lived largely upon the carcasses of animals dead of various diseases. As the animals fed on carcasses they fought, thus inoculating each other, so in the beginning the least resistant individuals died, the more resis- tant animals survived. Thus the constant fighting and inocu- lating has established in them a firm resistance that is trans- mitted to their progeny as a natural immunity. This immunity has become so fixed that it does not vary even in the domestic dog. The above is a plausible explanation of race or species immunity. The exact origin of individual immunity is considered IMMUNITY. 79 by some to be an acquired tolerance, 1. e., an acquired immunity, and by others, as simply an individual resistance not developed by having the disease to which the given individual is immune. Acquired immunity is an artficially produced condition by virtue of which the animal is capable of resisting disease, and , A Fig. 48.—The scab mite of sheep, Psoroptes Communis Ovis, magnified 150 diameters. is produced in an animal either in utero or after birth, and may be active (toxic, opsonic or bacterial), or passive (antitoxic). Active acquired immunity is, no doubt, the result of cellular action and may be produced as follows :— 1. By an animal becoming infected and recovering from an attack of the disease, e. g. blackleg. 2. By inoculation of a susceptible animal with a small quantity of the virulent causative microparasites, thus produc- ing the disease in a mild form. This is practiced in immunizing cattle against tick fever. 3. By inoculating a susceptible animal with an attenuated virus, (vaccine.) Horses, mules, cattle, and sheep are immun- ized to anthrax by a vaccine. 4, By inoculation of susceptible animals with a bacterin 80 VETERINARY PATHOLOGY. (dead bacteria) colts are immunized to strangles by the use of a strepto bacterin. 5. By repeated inoculations of a susceptible animal with small quantities of a toxin of a specific pathogenic microparasite, tetanus toxin or other active poison as snake venom. This method is used only in the production of antitoxins or in immun- izing animals against zootoxins and phytotoxins. Fig. 49.—Demodex Folliculorum, Fig. 50.—Demodex Folliculorum, variety Canis. variety Canis. Field showing various stages of Adult Male, magnified 4100 times development. showing wide head, with ros a. Ova. trum, short legs (3. articles b. Pupa. each) 2 claws and elongated e. Adult. body. d. ‘A, piece ‘of Scab. 6. By simultaneous inoculation with a virus and an antitoxin (antibodies, bactericidal substances, etc.). In the Philippine Islands this method is employed in immunizing cattle against rinderpest, and it is also being successfully used in the immun- ization of hogs, against cholera. Toxic immunity is the resistance to poisonous substances as toxins of bacterial origin, zootoxins and phytotoxins. It i common to hear sheep herders speak of dogs that are immune to the venom of rattlesnakes. The dogs are bitten frequently while doing duty on the range and although the reaction from the first inoculation is intense and may even kill, each succeed- ing inoculation produces less reaction until finally the dogs may Nn IMMUNITY. 81 be bitten or the venom inoculated with impunity. Immunity to intoxication diseases such as tetanus are of this type. The ab- sence of action of various therapeutic agents that have been given repeatedly may be explained on the principles similar to those involved in the production of immunity in dogs to snake venom. Toxic immunity is the result of the presence in the body fluids of an antibody (Antitoxin.) Opsonic immunity is the resistance of an infected animal due to a substance, opsonin that facilitates the destruction of bacteria by leucocytes. This is the type of immunity manifested in the human that is immune to typhoid, and the various animals that are immune to suppurative processes caused by the pyogenic micrococci, Bacterial immunity is the resistance an infected animal mani- fests to the bacterial invader. It is the result of bacteriolytic substances in the body fluids. Pfeiffer demonstrated that bacteria are destroyed when introduced into an immune animal. He introduced the spirilla of Asiatic cholera into the peritoneal cavity of guinea pigs and noted that the bacteria were soon rendered immobile, became swollen and granular and were finally disintegrated. This phenomena has been designated Pfeiffer’s reaction. Passive acquired immunity consists essentially of the presence in the tissues or body fluids of substances inimical to’ micro- parasitic activity, or substances capable of union with micro- parasitic products, (toxins) thus rendering them inert. This type of immunity is of short duration. It is usually produced by the inoculation of susceptible animals with antitoxin. In- jured animals inoculated with tetanus antitoxin at the time of injury are thus immunized to tetanus for a brief period. Acquired immunity, like natural immunity, is variable and inconstant. The production of active acquired immunity entails more risk than the production of passive acquired immunity. The causative agents or their toxic products are used in obtain- ing an active immunity and thus disease may be produced and the animal life sacrificed while the anti-toxin is used in the production of a passive immunity, without danger of the pro- duction of disease although transient disturbances may result from hemolysins, contained in the blood in which there is anti- toxin. Theories of acquired immunity.—Many theories have been advanced in explanation of acquired immunity, The chief of which are as follows :— 82 VETERINARY PATHOLOGY. 1. The Exhaustion Theory—This theory was championed by Pasteur, who proposed it about 1880. It is based upon the supposition that there are certain substances in the animal body that are food for micro-parasites and that these substances are uot regenerated. Hence when they have been consumed the micro-parasites cease to develop and the animal becomes im- mune. This theory is not tenable because immunity can be produced by bacterial products and by dead bacteria neither of which consume substances from the tissues of an animal immun- ized. 2. The Retention Theory—In the study of bacteriology it has been found that bacteria, like most other organisms, can not develop in the presence of a large quantity of their own excrements. This theory presupposes that bacterial products remain in a body after it has been infected and that these products prevent the future development of like bacteria. This theory does not explain the production of an immunity with toxines and is not supported by any scientists at the present time. The theory was proposed by Chauveau. 3. The Phagocytosis Theory—This theory was _ proposed independently by Sternberg and Metchnikoff about 1881. The theory was the outgrowth of the experimental study of the action of leucocytes upon bacteria and yeast, in which it was found that certain leucocytes are active in the destruction of various bacteria, yeast and tissue debris. These investigators designated those leucocytes active in the destruction of bacteria, phagocytes. Phagocytosis is a state or condition characterized by the development of phagocytes and the display of their special function. The supporters of this theory hold that the cells, which are active in the production of leucocytes transmit the property of phagocytosis to their progeny and thus immunity is perpetuated after it has been acquired. That phagocytes do incorporate bacteria and other foreign substances is not denied but it has not been demonstrated whether phaogocytosis is the cause or the result of immunity. This theory does not explain immunity from such diseases as tick fever. The microzoon of tick fever inhabits and usually destroys the red corpuscles. The leucocytes are probably not affected by them. In fact, the presence of the Piroplasma bigem- inum in leucocytes has not been noted. More recently Wright and Douglas have demonstrated that certain substances in the blood serum are necessary to prepare bacteria for phagocytic action. These substances have been designated opsonins. Opsonins are chemic substances in blood serum that render IMMUNITY. 83 bacteria subject to the action of phagocytes. Opsonins resem- ble the amboceptors of Ehrlich in action, but they are not iden- tical with them. ‘The action of opsonins is evidenced in pneu- monia, pyogenic infections, tuberculosis and probably in other diseased conditions. The opsonic index indicates the relative power of resistance due to phagocytic action in an animal body. 4. Humoral Theory.—After the phagocytic theory had been found insufficient, immunity was explained from a chemic view point. The supporters of this theory, among whom Buchner was active, demonstrated the bactericidal action of blood serum and lymph obtained from immune animals. Their demonstra- tions established the fact that immunity is due to a chemic substance, possibly an enzyme. But the origin and specific ac- tion of the chemicals in the production of immunity was not determined. The bacteriolytic substance of the body fluid called complement, was found to be destroyed by a temperature of 979) 5. Ehrlich’s Lateral Chain Theory—Ehrlich maintains that every living cell contains an active central body which produces unknown chemical substances that combine with and extend nutriment to the cell. These chemical substances, marginal chemic groups or lateral chains as they are variously called, for convenience of description are designated—receptors. These re- ceptors are specific in their nature; i. e., there are certain groups ef receptors that combine with certain kinds of nutritive sub- stances. Likewise there are present normally in the body celis certain groups of receptors which combine with disease produc- ing substances, e. g., toxins, which in turn destroy the body cells. It is thought that receptors for certain diseases are absent in certain species of animals and that because of this, there exists a natural immunity; e. g., the dog is immune to hog cholera be- cause his body cells do not have the specific receptors for that disease. If, on the other hand, the receptors that are normally present be increased in amount, an acquired immunity develops. Whenever there is an increase of the receptors in the body they become freed from the cells and are found in solution in the body fluids as antibodies. Experimentation has shown that antibodies are produced by the tissues as a result of the injection of a great variety of substances. These substances are known as antigens. Therefore, an antigen is any substance that when introduced into the body will stimulate the tissues to the production of antibodies. An antibody may be defined as any substance present in the body that has the property of antagonizing, neutralizing, precipi- tating, agglutinating or dissolving the substance (antigen) which 84 VETERINARY PATHOLOGY. has induced the production of such antibody. For example, the toxin of the tetanus bacillus when injected in minute, non-lethal doses, stimulates the production of antitoxin by the tissues; the toxin is the antigen, the antitoxin is the antibody. Likewise, blood serum when injected into a different species of animal would be an antigen and the precipitating substance produced by the tissues as a result, is the antibody. The following are some of the known antigens with their antibodies. This list is by no means complete but serves our purpose for the student of general pathology. Antigens. Antibodies. Toxins Antitoxins Ageglutinogens Agglutinins Precipitogens Precipitins Lysogens Lysins or Cytolysins. For convenience of study and because of difference in consti- tution Ehrlich has divided receptors into three separate varieties known as receptors of the First, Second, and Third orders. Ehrlich’s receptors of the first order,—(antitoxins). Toxins.—Toxins are antigens that when introduced into the body will stimulate the cells to the production of antitoxins. Excepting the fact that they give some of the protein reactions the chemical nature of toxins is not understood, but they can be demonstrated by certain biological tests. A number of plants and animals are known to produce toxins among which the following bacteria are important: Bacillus diphtheriae, the cause of diphtheria. Bacillus tetani, the cause of tetanus or lockjaw. Bacillus botulinus, the cause of certain cases of botulism or meat-poisoning. Bacillus pyocyaneus, the cause of blue pus. Ricin is a toxin found in the castor-oil bean, abrin comes from the jequirity bean and robin from the bark of the locust. Toxins have also been demonstrated in the venom of snakes, scorpions and spiders. A toxin is composed of two parts—a thermostabile (heat re- sistant) part, known as the haptophore or combining group, and a thermolabile (destroyed by heat at 56°C. for half an hour) group, designated as the toxophore. By careful heating at a lower temperature the toxophore only can be destroyed; in such a case the remaining haptophore group is known as a toxoid. A toxoid has the property of stimulating the body cells to the pro- duction of antitoxin but cannot exercise a toxic effect. IMMUNITY. 85 Antitoxins—li a large quantity of toxin, e. g. tetanus toxin, be injected into the body of a horse it will combine through the medium of its haptophorous group with all the available recep- tors (these being limited in amount in normal susceptible ani- mals) and cause death of the organism by destruction of its cells. If on the other hand only a small quantity of toxin be introduced, there will be injury instead of destruction of cells which together with their neighbors will be stimulated to the production of new receptors. Subsequent injections of increasing amounts of toxin further stimulate the production of receptors, which become freed from the cells as-antitoxin in the tissues. These free re- ceptors or antitoxin, as they are now known, combine with the toxin which they neutralize and immunity is the result. Anti- toxins as a rule are more stable than toxins but they can be de- stroyed by heat at 60°C. if sufficiently prolonged. Unlike toxins they are composed of only one group known as the haptophore or combining group. Ehrlich’s receptors of the second order. (Agglutinins and Precipitins.) It has been found that the blood of an animal immunized to certain diseases, e. g. glanders, when added to a culture of the specific organism causes the bacteria to clump together. This phenomenon is known as agglutination and the substance respon- sible for the process is called agglutinin. Likewise it has been discovered that protein substances used as antigens cause the production in the body of substances, known as precipitins which, when mixed with the protein in solution, will form a pre- cipitate. Unlike antitoxins, agglutinins and precipitins are di- vided into two portions—a combining or haptophore group, and an active agglutinating or precipitating—zymophore group. The zymophore group is unstable, and may be destroyed by heating to a temperature of 60° to 75° C. When an agglutinin has thus lost its zvymophore group the remaining haptophore is known as an agelutinoid. Likewise, a precipitoid is the combining group of a precipitin after its zymophore has been destroyed. Antigens which cause the production of agglutinins are known as ageglutinogens. Most foreign cells, as red blood cor- puscles, other body cells, protozoa and bacteria act as agglutino- gens when injected into the body. The following pathogenic bacteria cause agglutinin production: Bacillus typhosis, Bacil- lus mallei, Bacillus pestis, Spirillum Cholera, Bacillus tubercu- losis, and others. Advantage is taken of this fact and the ag- glutination test is used as a method of diagnosis in diseases pro- duced by some of these organisms. 86 VETERINARY PATHOLOGY. Antigens which stimulate the production of precipitins are known as precipitogens. Precipitogens are colloid substances in solution and are represented by such materials as, blood serum, milk, meat juices, egg white, etc. Agglutinogens are composed of a haptophore group only. Ehrlich’s receptors of the third order. (Lysins or Cytoly- sins. ) Lysins are antibodies which have the power of dissolving or disintegrating their respective antigens. Lysins may be sub- divided with reference to their antigens, into bacteriolysins, hemolysins, etc. Antigens which cause the production of lysins are known as lysogens and are represented by a variety of bac- teria, foreign cells as red blood corpuscels, etc. Lysogens are composed of a haptophore group only. Receptors of the third order or lysins are composed of two elements. A thermostabile substance which has two combining or haptophore groups and hence known as an ambocepter, and a thermolabile substance known as the complement or alexin. The amboceptor is specific; 1. e., it will combine only with that variety of lysogen which has caused its production. It is a com- bining element only and its presence is necessary for the lytic action of the complement. The two haptophore groups of the ambocepter are of different action; one is known as the cytophile and combines only with the lysogen; the other is called the com- plementophile and unites with the complement. Complement is found in varying quantities in all normal blood. It is non- specific—i. e., it is capable of combining with any variety of ambocepter and through this combination cause lysis. The complement has been found to consist of two groups—the hapto- phore, which combines with the amboceptor, and the zymophore or lytic group. Careful heating destroys the zymophore and the remaining haptophore is known as complementoid. Plate 1 represents graphically the production of the various orders of receptors and a careful study of the figures will enable the reader to grasp the subject more readily. Toxic immunity is explained by Ehrlich as follows: Toxins are composed of two essential chemic groups which are desig- nated haptophores and toxophores. The haptophore of the toxin has an affinity for the cell receptors. The union of the toxin haptophore and the cell receptor forms a medium through which the toxin toxophore passes to the central part of the cell where it exerts its action. The toxin haptophores are not injurious except as they enable the destructive toxin toxophore to reach the central cell mass. PLATE I. Graphic Representation of the Various Forms of Immunity According to Ehrlich’s Lateral Chain Theory. (Fig. 1—A—The bacterial cell or other substance which produces antigen, a, in the form of soluble toxin, al. B—tThe body cell which produces side chains or receptors of the first order, z, in the form of antitoxin, zl. a2—toxin uniting with receptor, z, injuring the body cell and stimulating it to the production of more receptors. zi—free antitoxin which at z2 is seen to be combining with and neutralizing the toxin a3. b—toxophore group and e haptophore group of toxin molecule. e2—toxoid after careful heating of toxin and destruction of toxophore bl, e3—toxoid combining with receptor; such a combination does not produce a toxic effect. Fig. 2.—A—Bacterial cell, foreign serum or whatnot which contains the antigen a, in the form of agglutinogen or precipitogen al. B—Body cell which produces receptors z, in the form of agglutinin or pre- cipitin zl. a2—ageglutinogen or precipitogen combining with the receptor z, and stimu- lating the body cell to the production of more receptors. z1i—freed receptor in the form of agglutinin or precipitin which is seen to combine at z2 with the antigen. This union results in agglutination or precipita- tion. x—haptophore group and y zymophore group of the antipody; careful heating will destroy the zymophore group and the remaining haptophore group, xl, is known as the agglutinoid or precipitoid. x2—ageglutinoid or precipitoid combining with the antigen. Agglutination or precipitation does not result from such union. Fig. 3.—A—Bacterial cell, red blood corpuscle or other body cell which con- tains antigem a, in the form of lysogen al. B—Body cell which produces receptors z in the form of amboceptors z1 and complement y, which together are known as lysin. a2—lysogen combining with the ambocepter and stimulating the body cell to the production of more ambocepters. y—complement, which is found in all normal serum. zi—freed amboceptor which is composed of two haptophore groups known as the cytophile x1, and the complementophile x2. C—shows a combination of lysogen, amboceptor and complement; this union results in lysis of the cell A. D—shows 2 combination of the lysogen and amboceptor only; the cell A is not destroyed by such union. The complement is composed of a zymophore group vl and a haptophore v2. Careful heating destroys the zymophore and the remaining haptophore is known as a complementoid v4. 4 ie ribet 1 ; taba Hct bit b insane ( ight Petar’ te aA ca ete Tk Thal ar Ae Ped Grr ae ‘ aber bik (ale di fh 2 a or Naaae VR Bhi aN PEGI MINA ye NP BPI i aS : fj Ba hyn ae i Pa rne 4 ; aie (y de PEA ei? 7 Cay > j un fe Ne Ae i ne A why UA TREN, si} : i ey ta Saly a anni nD : se ae I co i fea hee Heat) at Tey Arr Tod ai 1 Ae ne \" ra bees ips vig nee si alii vi nivel pen NS ‘ ay 4, MIVA, PS ens aes IMMUNITY. 8 Drawing by, H.C. Luce. / 88 VETERINARY PATHOLOGY. Toxin toxophores in the absence of toxin haptophores are inac- tive. The result of the union with, or action of, the toxin toxo- phore upon a cell may produce immediate destruction of the cell or it may stimulate the cell to produce more receptors. ‘The presence of toxin in the body fluids stimulates the body cells to produce receptors in excess. The increased receptors may remain in connection with the central body or they may become detached and float in the body fluids. Free receptors in blood serum is the essential active principle of antitoxin. Toxic im- munity may be better understood by giving an example. Examples.— Tetanus is an intoxication disease due to the pro- duction of toxins by localized bacterial activity of the tetanus bacillus. Immunity to tetanus is dependent upon the neutraliza- tion of the tetanus toxin. The tetanus toxin is composed of hap- tophores and toxophores. The body cells possess receptors capa- ble of union with the tetanus toxin haptophores. The union of cell receptors and tetanus toxin haptophores enables the tetanus toxin toxophore to act upon the central mass of the body cell, thus stimulating them to form more receptors. The excess recep- tors become detached and float free in the body fluids and com- bine with the tetanus toxin haptophore, thus preventing the lat- ter from combining with the attached cell receptors. ‘The te- tanus toxophores are not capable of combining with the central mass of the body cells except through the medium of tetanus toxin haptophores and if the tetanus toxin haptophores are locked up with the detached cell receptors, the tetanus toxo- phores remain inactive and the animal is not inconvenienced by their presence and is immune, Toxic immunity is therefore dependent upon first, sufficient free receptors to lock up the haptophores thus inhibiting the action of the toxophore or second, upon the absence of hapto- phores. Bacterial immunity —From the phenomena observed in Pfeif- fer’s reaction Ehrlich has proposed an hypothesis in explanation of bacterial immunity. As previously stated, normal blood serum contains bacteriolytic substances (see humoral theory). Comple- ments are destroyed by a temperature of 55°C. The blood serum of immune animals possess another substance, in addition to complement, not destroyed, by heating to 55°C. These are called amboceptors. According to Ehrlich, amboceptors, like toxins, are composed of two different combining groups, also designated haptophores and toxophores. The complemental substance of normal serum is not capable of action upon bacteria. The ambo- ceptor haptophore has an affinity for the complement of normal IMMUNITY. 89 serum. The amboceptor toxophore has an affinity only for bac- teria, but is not injurious to them. The amboceptor toxophore combined with or acting upon bacteria produces a condition favorable for the action of the combined amboceptor haptophore and complement, i. e., this enables the complement to cause dis- integration of bacteria. The amboceptor thus renders condi- tions favorable, 1. e., makes it possible for the bacteriolytic sub- stance, the complement, to exert destructive action upon bacteria, the amboceptor acting as middle man. Opsonic immunity—Opsonins are produced by some animal tissue, probably muscle. Opsonic production is the result of stimulation with endotoxins. Endotoxins are products or are an integral part of bacteria. | Opsonins increase the destroying power of leucocytes or diminish the resistance of bacteria. (Cle Veve TBR We MALFORMATIONS. DEFINITION. ETIOLOGY. Intrinsic (heredity). Extrinsic, Pressure, Amniotic Adhesion. Excessive Motion, Malnutrition. CGEAS SES: Single. ; Result of Arrested Development. Result of Excessive Development. Result of Transposed Visceral Organs. Result of Persistent Foetal Structures. Result of Mixed Sexual Organs. Double or Multiple. Symmetrical Duplicities. Complete. Incomplete. Asymmetrical Duplicities. Multiple. During the embryonic stage of intra-uterine life the special- ized tissues and organs are formed. The foetal period is the time during which the structures formed in the embryonic stage grow and develop. At birth the young of a given species are of a definite shape, contour and type; the form or type which is most common is accepted as normal; and deviations from the normal are designated malformations, anomalies or develop- mental errors. Many new strains and breeds of stock have been the result of developmental errors becoming a fixed peculiarity. Thus the polled cattle, the Boston bull-dog, the Mexican (hair- less) dog, and the five toed chicken had their origin. Etiology. Malformations may be brought about by pre- existing influences in the maternal cells, (internal or intrinsic causes), or from external influences (external or extrinsic causes). Internal or Intrinsic Causes—Internal causes are inherited peculiarities, i. e., heredity and atavismal influences. These are probably not the usual causes of malformation in domestic ani- mals for malformed individuals excepting cryptorchidism and animals affected with prognathism and some other of lesser de- fects are rarely used for breeding purposes. 90 MALFORMATIONS. 91 External or Extrinsic Causes of malformations are pressure, amniotic adhesions, excessive motion, insufficient or abnormal nutrition, infectious diseases, etc. External causes exert their influence during the embryonic or formative period and they must act in a mild degree or death of the embryo and abortion follows. Typical malformations are approximately of the same form and are usually produced by similar causes. Atypical mal- formations are variable in form and may be produced by a variety of causes. A complete description of all malformations is beyond the scope of general pathology. A general classification with a de- scription and origin of the most striking malformations is all that will be attempted in this chapter. Malformations may be divided into two classes: 1st, Single malformations, and 2nd, Double or multiple malformations. Single malformations are those affecting a single individual. Single malformations may be grouped into five classes as fol- lows: Malformations resulting from; (a) arrested growth or development; (b) excessive growth or development; (c) trans- position of visceral organs; (d) persistent foetal structures; (e) mixture of sexual organs. ARRESTED DEVELOPMENT.—Malformations caused by arrested development may involve an entire individual or any part of an individual. Arrested development of the entire individual results in the formation. of an irregular, fleshy mass, called a mole, in place of the normal foetus. Moles may be carried in the uterus for the entire period of gestation. In some instances a mole and a normal foetus may be delivered at the same time. Moles have been observed in mares, more rarely in cows. Malformations resulting from arrested development of a part may be manifested by the entire absence of the part (aplasia), by underdevelopment of the part, (hypoplasia), or by a lack of union or fusion of tissue (schistosis and atresia). The fol- lowing malformations are the result of local aplasia. Acephalus. A name applied to a headless monstrosity. Acephalus is probably the result of amniotic adhesions. Atrichia. A defect in which there is no hair. This results from some disturbance of cutaneous development. Amyelus. A malformation in which the spinal cord is absent. Defects of the primitive streak or failure of production of the neural canal interferes with or prohibits the formation of the spinal cord and is the cause of amyelus. 92 VETERINARY PATHOLOGY. Acardia. A heartless monstrosity. Agastria. A malformation in which the affected individual has no stomach. This may be due to lack of sacculation of the embryonic gut. Acaudia. A malformed individual in which the defect con- sists in the absence of the tail. An acaudia fox terrier bitch was recently observed, her mother whelped one or two tailless puppies at each whelping. This bitch recently whelped an acaudiac puppy. Aprosopus. An individual having no face. Dithoracisamelus. Fig. 51.—This picture taken when calf was five months old. The animal was able to get about by walking in an upright position and could gain its feet unassisted. Case observed by Dr. Smith V. Ewers. Agnathus. A term used to designate an individual in whi-h the inferior maxilla is absent. This is common in lambs. Amelus. The name of a limbless or legless individual. Ame- lus is the result of arrested development of leg buds and is usual- ly caused by unequal intrauterine pressure or amniotic adhesions. Monopygusamelus. A monstrosity in which one posterior leg is wanting. This is due to arrested development of leg buds, probably due to amniotic adhesions. Dipygusamelus. The name of a malformed animal in which both posterior legs are absent. Result of arrested development of leg buds. MALFORMATIONS. 93 Monothoracisamelus and dithoracisamelus are monstrosities in which one and both front legs are absent respectively. Apus. A name applied to a malformation in which the feet are absent. This may be the result of intrauterine amputation or amniotic adhesions. Monopygusapus is an individual in which one hind foot is wanting and a dipygusapus, an individual in which both hind feet are absent. Monothoracisapus, and dithoracisapus, are names implying the absence of one or both front feet. The following malformations are the result of under develop- ment or undergrowth. (Hypoplasia). Microcephalus, a term used to designate an individual hav- ing a diminished sized head, also used to designate the small head itself. This is probably the result of diminished nutrition to the head and anterior part of the body during embryonic and foetal development. Micro-cardia. A name applied to an individual having a small heart. This may be due to excessive pressure. Microophthalmia. A term used to indicate a malformation in which the eye or eyes are smaller in size than the normal. This is probably the result of insufficient nutrition. Micrognathy. The name of an individual having a diminutive inferior maxilla. These are caused by undue pressure or insufficient nutrition. Micromelus. A malformation so named because of the dimin- ished size of all legs. This is caused either by diminished nutrition or undue pressure. The following are illustrations of arrested development mani- fested by absence of imperfect tissue union, thus producing fissures (schistoses), or resulting in fusion of parts that are normally separate (synactoses). Fissures of the body cavities are due to increased accumulation of fluids in internal organs, increased size of internal organs, prolapse of viscera before body walls have united, the presence of amniotic folds between cleft edges or lack of sufficient tissues to close the margins. Cranioschisis. The name of a condition produced by fail- ure of development and union of the cranial bones and resulting in a cleft. The meninges and in some instances the brain tissue may be exposed or there may be protusion of the meninges and also of the nerve tissue, thus producing meningocele or men- ingo-encephalocele. ; 94 VETERINARY PATHOLOGY. Craniorrhachischisis. A malformed individual so called because of a fissure of the spine and cranium accompanied by exposure or protrusion of the spinal cord or brain, Rachischisis. A condition in which there is a cleft of the spinal column, This malformation is usually the result of some defect in the margins of the neural groove. If the fissure ex- tends the entire length of the spinal column the resulting con- dition is called holoschisis. If the fissure does not extend the entire length of the spinal column, the condition is termed meroschisis (Gr. Meros=part, and schisis=splitting.) The spinal meninges may protrude through the spinal column fissure Fig. 52.--Cranioschisis—Calf, producing spina-bifida. A hernia of the spinal meninx that con- tains cerebrospinal fluid is termed spinal meningocele, and if the cord and meninges protrude, it is called a myelomeningocele. Cheiloschisis, is the condition resulting from arrested develop- ment of the soft tissues covering the maxilla. This is the condition popularly termed hair lip. It is an inconvenience because it inter- feres with sucking the teat, the source of nutrient of the new born mammal. The defect may also involve the maxilla producing cheiliognathoschisis. Palatoschisis. A defect in which the palatine processes have imperfectly developed, thus leaving a fissure through which there is free communication between the nasal and_ buccal MALFORMATIONS. 95 cavities. This condition is commonly spoken of as cleft palate. Thoracoschisis. A condition resulting from failure of union of the thoracic walls. The thoracic viscera, the lung, heart and large vessels may protrude through the fissure thus producing ectopiacordis or ectopiacordispulmonaris. Y Fig. 53.—Cheiloschisis, Abdomuinoschisis, is the condition caused by failure of union of the abdominal parieties. The condition is frequently accom- panied by protusion of the abdominal viscera through the fissure. The abdominal fissure may involve only a portion of the cavity or it may be complete. Ectopia gastrium is the condition result- ing from protusion of the stomach through an abdominal fis- sure; ectopia vesicae, protrusion of bladder, etc. Hypospadias is a condition resulting from arrested develop- ment of the penis and scrotum. The principle defect in hypos- padias consists of a variable cleft in the posterior and inferior 96 VETERINARY PATHOLOGY. Fig. 54.—Palatoschisis. surface of the penis and scrotum. This cleft which represents the urethra is lined with mucous membrane and into it urine 1s discharged. This is the most common malformation of thc male genital organs. Raymond Pearl reported his observation Fig. 55.—Abdominoschisis. MALFORMATIONS. 97 on a case of hypospadias in a lamb in the American Veterinary Review. Synophthalmia, or cyclopia (Gr. Kuklops=mythical single eye monster), is a condition resulting from the fusion of the optical vesicles. Arrested development of the anteriar cerebral vesicles allows the optical vesicles to contact and in some instances there is one large double eye centrally located or there may be two eyes occurring in a centrally located orbit. Cyclopia is usually associated with defects of the nose. Synactosis is a general term denoting a condition caused by the fusion of parts or organs that are normally separate. Synmelus. A malformation caused by the fusion of two legs into one irregular member. Fig. 56.—Synophthalmia or Cyclopia. Syndactylus. An individual having the digits fused or grown together. An illustration of syndactylism is the soliped hog. The soliped hog usually has two separate digits of three pha- langes each and the ossa pedes are encased in a single hoof. Synmelusdipus. A malformation having fused legs and two feet. Synmelusmonopus. An individual having fused legs and only one foot. Synmelusapus. A monster having fused legs and no feet. Synorchism. A malformed animal in which the testicles are fused. Arrested developmert may be evidenced by the nonappear- ance of the lumen in any of the natural hollow organs, (atresia). The mouth is formed by an ingrowth of the ectoderm and the buccal cavity extends inward until it meets the anterior elonga- tion of the embryonic gut. Later the partition separating the buccal cavity and the cavity of the embryonic gut is absorbed and thus the cavities become continuous. Failure of the exten- 98 VETERINARY PATHOLOGY. sion of the mouth cavity and its fusion with the embryonic gut constitutes the condition atresia oris. Atresia iridis. A defect in the eye due to the absence of an cpening (pupil). ; Atresia oculi, a malformation in which there is no opening between the eyelids. Atresia anus is a condition in which there is an imperforate anus, that is, there has been failure of union and fusion of the anal ingrowth and the rectal outgrowth. Atresia anus is ol rather frequent occurrence and usually the defect is easily re- lieved. Fig. 57.—A condition of Scolipedia in a hog. _Atresia urethra. Imperforation of the urethra. MALFORMATIONS RESULTING FROM EXCESSIVE DEVELOPMENT OR OVERGROWTH.—Excessive development is usually evidenced as a multiplicity of digits or phalanges though there may be mult?- plicity of any structure. Polydactylism—The name applied to a malformed individual in which there is an excessive number of digits. Individuals having supernumerary digits are frequently observed. The condition is probably more frequently observed in hogs than in other animals. Polydactylism, however, occurs occasionally in the ox and horse. Polymelusthoracicus—This is a malformation in which the affected animal has one or more extra front legs. An interest- ing case was observed in a cow in which there was an irregular. | MALFORMATIONS. 99 bone attached to the right scapula, and extending across the median line. This bone articulated with an irregular supernum- erary scapula and also with the spine of the left scapula. This irregular formed scapula articulated with another bone which was similar to a humerus on the distal end of which there was a rudimentary ulnar. The condition of supernumerary posterior legs is termed polymeluspygus. Dicaudis—An individual having two tails. This type of malformation is not very common. It is probably the result of a division or cleavage of the caudal segments during embryonic formation. Fig. 58.—Polydactylism in a hog. Multiplicity of internal organs is occasionally observed. Thus several cases. of partially double spleens have been reported. An interesting case of malformation was observed in a hog, the defect consisting of a double penis. This individual may have been called a dipenis. Malformations from excessive growth may be applied to the entire animal when it is excessively large (giants). Malforma- tions resulting from the overgrowth of a part are frequent, thus one foot, one leg, the head or any other part may be overgrown. Darwin, (in Plants and Animals under Domestication), men- tions a cat that he observed which had incisor teeth one and one half inches in length, : 100 VETERINARY PATHOLOGY, Fig. 59.—Prognathism, common name “undershot.” TRANSPOSITION OF VISCERAL ORGANS, (situs viscerum inversus). Very rarely animals are observed in which the visceral organs are re-arranged, 1. e., those organs that normally occur on the left side of the body are found on the right side. A sheep in prime condition was observed which was normal in appearance o ths wee © MALFORMATIONS. 101 except its head was turned slightly to the left and the atlas was ankylosed to the occipital, thus giving it but little vertical motion. The right shoulder was anterior to the left. The vis- cera were entirely reversed; the heart was hanging toward the right; the four compartments of the stomach were transposed, the rumen being on the right side, and the spleen being in con- tact with the right side of the diaphragm; the liver was on the left side and the right kidney was posterior to the left which was swinging free as the right usually does. Fig. 60.—Schistosis melus anticus or dimelus anticus—Male. (Drawing made from a photograph.) Transposition of visceral organs probably results from an irregularity to the allantoic veins and their continuation. In normal development the right vein atrophies and the left vein becomes larger in early embryonic life and if for any reason the left vein atrophies and the right vein becomes longer then the visceral organs tend to develop in the reverse position. PERSISTENT FOETAL STRUCTURES.—AIl the malformations are grouped into this class that retain embryonic or foetal structures abnormal to extra-uterine forms of life, ; 102 VETERINARY PATHOLOGY. Foramen ovale.—An occasional case is observed in which there is a persistent foramen ovale. The right and left auricles com- municate through the foramen ovale during the foetal stage of life. This communication normally ceases at the time of birth. The foramen may not entirely close and thus the blood in the left ventricle will be mixed. Such a case was observed by A. Leslie, the patient being a pure bred 15 months old Guernsey heifer. The foramen ovale had persisted, it was oval and one- half inch in diameter. This case also presented an interventri- cular communication. Cryptorchids—(Gr. Kruptein=to hide and orchis-testicle) are probably the most frequent malformations resulting from the persistence of a foetal structure. The testicles of domestic ani- mals are formed within the abdominal cavity during embryonic life and later migrate, except in fowls, birds, etc., to their per- manent position in the scrotum. Cryptorchids are animals in which the testicle was properly formed, but did not descend to the scrotum. Dr. DeWolf carefully inspected 4671 male hogs and found 28 single and 7 double cryptorchids. Cloacal persistence —During embryonic life the rectum and uro- genital tract terminate in one common cavity known as the cloaca. The cloaca persists throughout life in the avidae, but not in mammalia. H. Brassy Edwards, M. R. C. V. S., reported a case in the veterinary Journal of an imperforate anus in a brindle bull bitch pup 10 days old. There was no trace of an anus and the prominence usually felt in the perineal region of imperforate anus was also absent. On operation the rectum and uterus were found to be fused, thus producing a cloaca. Dr. P. Phillipson of Holbrook, Nebr., reported a colt in which there was a cloacal formation. In this case the floating colon fused with the uterus and the vagina was a common opening of the digestive tract and the genito-urinary tract. Cervical ectopia cordis—This is the name of a malformation in which the heart is located in the cervical region. The heart is normally formed in the embryo in the cervical region and if the anterior thoracic wall closes prematurely, the heart remains in that region. Hymen persistence ——The extent of the hymen is quite variable. Ordinarily the hymen consists of a fold in the vaginal mucous membrane from which a delicate web like structure may com- pletely divide the vagina. In some instances the hymen is com- posed of dense fibrous tissue which interferes with or prevents successful copulation MALFORMATIONS. 103 MIXTURE OF SEXUAL ORGANS, HERMAPHRODITISM.—The sexual glands, ovaries and testicles, and the external genitals, of both sexes, are derived from four similar embryonic structures. The influence or factors determining sex are not known. During embryonic development the sexual determination is not distinct, the individual possessing more or less complete sexual organs typical of both the male and the female. Animals in which there is a combination of sexual organs are termed hermaphro- dites. According to the development of sexual organs, herma- phrodites are designated as true and pseudo or false herma- phrodites. A true hermaphrodite possesses secreting sexual glands of both sexes, 1. e., they have secreting ovarian and testicular tissues. The external genitals of the true hermaphrodite may be bisex- ual or unisexual. True hermaphrodites are rare, and fertility of such animals is doubtful. True hermaphroditism may be lateral, bilateral or unilateral. Lateral hermaphroditism is the condition in which there is an ovary on one side and a testicle on the other. The following example illustrates this type. The animal was a two year old bovine and had an ovary suspended by the left broad ligament and a testicle suspended by the right broad ligament. The two glands had their normal appearance, typical of ovarian and tes- ticular tissues. This type of hermaphroditism is rare. Bilateral hermaphroditism is typified by the presence on both sides of an ovary and a testicle, or a single organ on each side containing ovarian and testicular tissues. This type of her- maphroditism also is rare. Unilateral hermaphroditism is characterized by the presence of a single organ, as an ovary or testicle on one side and an ovary and testicle on the other side or an organ containing ovarian and testicular tissue on one side. This type is not common. Pseudo, or false hermaphroditcs, are individuals having one distinct type of sexual glandular tissue and in which the exter- nal genitals partake of the nature of both sexes. This type of malformation is more common in the male and is usually the result of persistence of Mullers canal and the further develop- ment of the uterus and Fallopian tubes. In pseudohermaphro- ditism the testicles are usually retained in the abdominal cav- ity. There are usually Fallopian tubes, vagina and uterus, the completeness of which is variable. The appearance of the testi- cle is variable according to the development of the female ex- ternal genitals. Pseudohermaphroditism is much less frequent in the female than in the male. 104 VETERINARY PATHOLOGY. A rather well marked case of a pseudohermaphroditic horse was obtained and carefully observed for some time after which it was destroyed and the type and relation of the sexual organs Fig. 61.—Pseudo-hermaphrodite. were determined by dissection. In this animal the head and neck while not decisive of either sex in general rather favored the male in conformation. There was quite a well marked vulva and the much elongated clitoris projected about four inches postero-inferiorly and closely resembled a penis. The uterus was quite rudimentary and the reproductive glands were located near the normal location of the internal inguinal ring and had MALFORMATIONS. 105 very little resemblance to either testicle or ovary. Microscopic examination did not solve the difficulty for the glands were a conglomerate of small cysts. The mammary gland was fairly well developed. Double or Multiple Malformations.—Under this caption those malformations will be considered that involve two or more in- dividuals developing simultaneously. Marchand’s classification of duplicate monsters is adhered to in the following discussion. The entire subject of duplicate monsters may be subdivided into ist, symmetrical duplicity, 2nd, asymmetrical duplicity, and 3rd, multiplicity. SYMMETRICAL DUPLICITy.—The individuals, in symmetrical duplicity are, in the beginning, similar and symmetrical. Each of the symmetrical duplicates is derived from separate, similar, equal anlagen of a single fertilized ovum or bisection of a single anlagen. This class of malformations may be divided into two groups :—viz., complete and incomplete duplicities. Complete duplicity—Complete duplicates are in the beginning alike and complete and the individuals may remain separate thus forming twins, (free duplicities,) or they may be united, thus forming double monsters. Twins, (free duplicates), develop in a single chorin though each individual usually has a separate amnion and _ allantois. Monochorionic duplicates may develop equally or unequally, depending upon the division of nourishment. The above dis- cussion primarily applies to uniparous animals. However, by varying the number it is equally applicable to multipares. Twins may also result from simultaneous fertilization of two ova. Double monsters are mono-chorionic duplicities in which the bodies are united. The two bodies may be equal or unequal in size, depending upon the distribution of nourishment. Double monsters are the result of partial fission of a fertilized ovum, partial fusion of two separate anlagen of a single ovum, or par- tial fusion of two fertilized ova. The attachment of the two bodies of the double monsters may be posterior, middle or anter- ior. Posterior union may be dorsal or ventral. In the former the union occurs at the pelvis, and the dorsal surfaces of the bodies are usually in apposition; such a monster is called a pygopagus. Pygopagi have two umbilical cords which fuse to form a single cord; coccyx and sacrum are single, rectum and anus usually single; spinal cord double anteriorly, fused posteriorly forming a single filum terminale; urogenital system usually double. Ven- tral posterior union may be confined to the pelvic région, 106 VETERINARY PATHOLOGY. (ischiopagus), or it may extend anteriorly to and including the thoracic cavity, (thoracisischiopagus) The two bodies in ven- tral posterior union are so united that their venter surfaces are in opposition. Ischiopagi, usually have a single umbilicus and cord; pelvic organs may be single or multiple; there is usually no anus. If one of the bodies is small or rudimentary, it is desig- nated a parasite, (ischiopagusparasiticus). Thoracoischiopagi, may have single or double thoracic viscera; the abdominal vis- cera are usually double. Middle union in double monsters occurs on the venter sur- face from the umbilicus and extends anteriorly. There is usu- ally a single umbilicus; the abdominal viscera is usually double; thoracic viscera single or double, depending upon the area of union; middle union may occur at the xiphoid cartilage, (xipho- pagus), involve the entire sternum, (sternopagus), or the entire thoracic venter surface, (thoracopagus), xiphopagi may survive, the “Siamese Twins,” were of this type. Thoracopagi are fre- quently unequal in size, the smaller one being designated as a parasite. Anterior union may be dorsal or ventral or the union may be on the anterior surface of the head. Dorsal, anterior union rare- ly occurs, the attachment being on the frontal region. These malformations are designated Craniopagi. Ventral anterior MALFORMATIONS. 107 union occurs occasionally. The union in this type is along the venter cervical region and extends onto the venter thoracic re- gion. The sternum and oesophagus are single; larynx, trachea and stomach may be single or double; intestine double; there may be two faces or the faces may be fused. Fused-face mon- sters resulting from union of the venter anterior cervical or cephalic regions are called syncephali. Fig. 63.—Dicepkalie Calf. Incomplete duplicity 1s the name applied to those malformations in which the greater part of the body is single, duplication oc- curring in only a part. The duplicity may involve any part. These malformations are not easily differentiated from malfor- mations. resulting from multiplicity of parts as polydactylism. ASYMMETRICAL DUPLICITY are those malformations resulting from the development of two separate, dissimilar, unequal anlagen of a single ovum, the development of a fertilized polar body or the development of an isolated group of segmentation cells. In asymmetrical duplicity one body is rudimentary or under-developed, (the parasite), and the other body develops normally or nearly so, (the autosite). The parasite always re- mains attached to the autosite or is included by it. Pardsitic 108 VETERINARY PATHOLOGY. duplicity may occur in any region. Thus the parasite may pro- ject from the orbit, mouth, shoulder or it may be included in the thoracic or abdominal cavities. MULTIPLICITY is the name applied to designate the development of more than two separate individuals in a single choricn. Mul- tiplicity is of rare occurrence. One single case has been authen- tically reported in the human in the form of a tricephalus. CHAPTER: CIRCULATORY DISTURBANCES. Normal blood circulation is dependent upon normal rate, rhythm and force of the heart, normal caliber of the blood ves- sels and the normal resistance offered by them and the quantity and the quality of the blood. Variation of Heart Action.—A marked variation in the heart activity results in imperfect circulation. Depressed or diminished heart action is more common than increased heart action. Di- minished functional activity is most frequently caused by in- flammation of the endocardium, myocardium, epicardium or per- icardium. Valvular stenosis and valvular insufficiency are the result of endocarditis. Myocarditis diminishes the activity of the heart and if the inflammation is long continued the muscle cells are destroyed and then replaced by fibrous tissue thus per- manently impairing the force of the heart. Inflammation of the epicardium and pericardium may be accompanied by volumin- ous exudation which distends the pericardial sac and produces sufficient pressure to hinder diastole, or the exudate may be- come coagulated and later organized attaching the sac to the surface of the heart and thus hindering cardiac systole. Cardiac activity may be diminished by the collection of fluid in the pleural cavity, malformed thoracic cavity, tumors, occlusion of coronary arteries, fatigue and thrombic formation upon the car- diac valves. Diminished cardiac activity results in a diminished quantity of blood being sent out from the heart and an accumu- lation of waste products in the tissues. Increased functional activity of the heart is usually only tem- porary excepting in those animals affected with cardiac com- pensatory hypertrophy. The most common cause of increased cardiac activity is reflex stimulation. Increased activity due to reflex stimulation may terminate in exhaustion and syncope in a relatively short time. Increased functional activity, due to a cardiac compensatory hypertrophy resulting from increased resistance as in emphysema, chronic nephritis, etc., may result in permanent over action of the heart. Anatomical changes in the cardiac-structure, as hypertrophy, fatty degeneration, fragmentation, fibrous formation, or necrosis 109 110 VETERINARY PATHOLOGY. may be evident when the functional activity of the heart is varied. Vascular Variations.—The amount of blood passing into or out of a given organ is determined by the caliber of the blood vessels, provided the heart action and general blood pressure remain normal. Variations in the caliber of normal blood ves- sels depend primarily upon the response of the vessel muscu- lature to vaso-motor stimulation. Blood pressure is dependent upon the elasticity of the arteries and the force of the heart. In general, pathologic vascular variations are the result of, first, disturbed arterial elasticity ; second, variation of the normal cal- iber of the vessels and; third, abnormal permeability of the vas- cular walls. _ Arteriosclerosis is a condition in which the elasticity of the vessel walls is lessened or destroyed. In the production of arteriosclerosis there is vascular dilatation succeeded by supen- dothelial fibrous formation which continues until the lumen of the dilated vessel is reduced to its normal size. The hyper- plastic fibrous tissue may later become calcified. Sclerotic ar- teries are thick, stiff and nonelastic. Sclerosis is most common in arteries although it occurs in veins. The vascular caliber may be diminished by muscular con- traction or by liypertrophied vessel walls. In animals affected with chronic nephritis there is contraction of the systemic ar- teries resulting in compensatory cardiac hypertrophy. Arterial constriction is also common in the peripheral vessels of animals affected with carbon dioxide poisoning. Local diminution of vascular caliber may be produced by parietal thrombi, The vascular caliber may be increased by paralysis of the vaso-motor nerves, a condition which is sometimes observed in animals that have received injuries in the cervical region, Increased permeability of vessel walls usually results from insufficient nutriment to the vascular structures and occurs most frequently in small vessels, i. e., capillaries and venules. In- creased permeability usually accompanies venous hyperemia, although it may exist independent of variations in the quantity of blood. Thus oedema is common in hydremic individuals. Variations in Quantity and Quality of Blood—The quantity of blood in a part is determined by the caliber of the supplying vessel and by the blood pressure. Acute general anemia re- sults in a diminished blood pressure which, if not corrected in a short time, terminates fatally. Chronic general anemia is ac- companied by a slightly diminished blood pressure and a re- tarded blood current. CIRCULATORY DISTURBANCES. et The most important variations in the quality of blood that concerns the student of general pathology are due to the varia- tions of the percentage of water contained. Hydremia is ac- companied by disturbances of the renal function and by oedema. Anhydremia is productive of a slow weak pulse and the sec- ondary changes resulting therefrom. Excess of carbon dioxide or urea in the blood stimulates the vaso-constrictor nerves thus causing arterial contraction, HEMORRHAGE. DEFINITION. ETIOLOGY. Predisposition (hemophilia). Ruptured vessel. Rhexis or diabrosis, Increased permeability. Diapedesis. VARIETIES. Location. Tissue. Petechia (flea bite) pin point. Ecchymosis (over-low) from pin point to size of dime. Suggillation (swelling) bruise. Effusion, Hematoma (blood tumor). Infarction. Surface—Skin, mucous, membrane, serous membrane. Epistaxis, Hematemesis. Hemoptysis. Hematuria, Hematidrosis. Hematometra. Hematocele. Metrorrhagia. Hemathorax. Hemocoelia, etc. Vessels. Cardium. Arteries. Veins. Capillaries. APPEARANCE. Macroscopic. Microscopic. Tissue hemorrhage. Clot. EFFECTS. Rate of outhow. Location. Secondary change of extravasate. Hemorrhage is the escape of blood from a vessel, (capillary, vein, artery or heart.) Etiology.—Some animals are predisposed to hemorrhage (hemophilia). Hemorrhagic diathesis or hemophilia is an_in- herited condition in which there is little or no tendency for co- 112 VETERINARY PATHOLOGY. aguiation of blood. The cause of this condition is the absence of some blood constituent essential to coagulation. This type of hemorrhage sometimes occurs in colts, usually appearing at the time or within a few days after foaling. In those cases that occur at the time of foaling the hemorrhage is usually from the umbilical vessels although there may be some cutaneous capillary hemorrhage, (hematidrosis). In some cases there may be no evidence of hemorrhage at the time of foaling, but within from 24 hours to three or four days, oozing of blood on to the skin surface may be noticed, the extent of which varies and may or may not be fatal. Gough, of Benton, Ky., reported a case of hemophilia in a mule colt in the American Journal of Veterinary Medicine, July, 1911. A case of hemophilia in a medium sized 17 months old Ger- man sheep dog was reported by L. & E. Lepmay. This dog first showed tendency to hemophilia at 15 months of age, by per- sisted hemorrhage from the mucous membrane of the gums. A little later a subcutaneous hemorrhagic extravasate was observed in the thoraco-axillary region and the dog died of acute intesti- nal hemorrhage when about 17 months of age. Hemorrhage may be caused by degeneration or ulceration of the vessel wall—thus hemorrhage by diabrosis is produced ; it may be caused by rupture of the vessel wall due to increased intravascular or diminished extravascular pressure and trauma of the vessel wall —thus hemorrhage by rhe-vis is produced; or it may be increased permeability of the vessel walls due to increased intravascular press- ure or disease of the vessel wall—thus hemorrhage by diapedesis is produced. Diabrotic hemorrhage is observed in tumors as a result of the destruction of the vessel wall by the neoplasm; gastric ulcers particularly in dogs; glanders, especially the acute type in which the mucous membrane of the respiratory tract becomes necrotic ; in septic wounds, etc. Hemorrhage by rhexis is the type most common, it is the type observed in traumatisms, and is sometimes observed in apoplexy resulting from vascular occlusion (apoplectiform anthrax), this type has also been observed in some cases of canine vascular strongylosis due to infestation of the strongylus vasorum. Diapedetic hemorrhage is rather uncommon, being observed occasionally in such disease as purpura hemorrhagica and in some septicaemias. The escaped blood, i. e., the extravasate, may flow upon the surface of the skin, serous or mucous membranes, or into the tissues. CIRCULATORY DISTURBANCES. 113 TISSUE HEMORRHAGES may vary greatly in amount and are designated by the following terms, petechia, ecchymosis, sug- gilation, effusion, infarction and hematoma. Petechiae are small sharply defined hemorrhagic points and are probably caused by bacterial products in the blood. Ecchymoses are hemorrhagic spots larger than petechiae and less sharply defined caused by rupture of capillaries or precapil- laries. Ecchmymotic hemorrhages are of common occurrence in the nasal and ocular mucous membrane of horses affected with purpura hemorrhagia and equine infectious anemia. Fig. 64.—Petechial hemorrhage, Kidney hog cholera lesion. a. Hemorrhagic area, ec. Glomerulus engorged with blood. b. Normal kidney tubule. Suggulations and effusions are large indefinable hemorrhagic areas, caused by bruising which ruptures the small vessels. Hemorrhagic infarction is a hemorrhage into an anemic area. This is not a hemorrhage as ordinarily understood, for the blood is within the vessels and escapes into the anemic area because of the diminished pressure. A hematoma is a circumscribed collection of extravasated blood in the tissues and is usually the result of hemorrhage from an artery. 114 VETERINARY PATHOLOGY. SURFACE HEMORRHAGE 1s designated according to its origin, thus: Epistaxis is hemorrhage from the nasal mucous membrane and is quite common in acute nasal glanders. Hematemesis is hemorrhage from the stomach and is observed in animals poisoned with arsenic and those afflicted with gastric ulcer or gastric carcinoma. The hemorrhagic extravasate is act- ed upon by the acid gastric content and converted into coffee bean like masses. These masses, which are dark in color, char- acterize gastric hemorrhage. Woaematoma rote ee > eis eee ern ones steamed Fig. 65.—Hematoma, caused by rupture of spur vein. Hemoptysis is hemorrhage from the lungs. It may be the result of excessive exertion, abscess formation, tuberculosis,. Pulmonary hemorrhage is characterized clinically by the dis- charge from the nose or mouth of a frothy sanguinous extra- vasate. Hematuria is hemorrhage into the urinary tract or bloody urine. The blood may escape from the kidney, and if so theré will be tubular casts discernible on microscopic examination of the urine; it may come from the ureter or bladder, and would then CIRCULATORY DISTURBANCES. Ul) be thoroughly mixed with the urine; or it may have its origin from the urethra and would not be mixed with the urine but would usually precede it. Hematidrosis is hemorrhage from the surface of the skin and is the so-called sweating of the blood and is caused by increased permeability of cutaneous capillaries. Enterorrhagia is hemorrhage from the intestinal mucosa and may be differentiated from hematemesis by the appearance of the extravasate in the feces. The extravasate in hematemesis has the appearance of coffee bean grains in the feces while the enterorrhagia extravasate retains the hemoglobin color and is not broken up into granules. (The coffee bean appearance of blood extravasated into the stomach is due to the action of the hydrochloric acid of the gastric juice.) Enterorrhagia is caused by infection as in anthrax and by caustics. Hematometra is hemorrhage from the uterine mucosa, the extra- vasate being almost entirely retained in the uterus. This is usually caused by improper removal of retained placenta. Metorrhagia is hemorrhage from the uterine mucosa and the extravasate passes out of the uterus. Menstruation in the hu- man is an illustration of metrorrhagia. Hemocoelia is hemorrhage into the peritoneal cavity and is caused by rupture of the peritoneaum or some abdominal organ. Hemothorax is hemorrhage in the pleural cavity, and is caused by ruptured pleura as a result of fracture of a rib, ete. FHematocele is hemorrhage into the tunica vaginalis cavity. This may be the result of laceration or rupture of the tunica vaginalis testis. Effects.—The effects of a hemorrhage depend upon the quan- tity of blood lost and the location and secondary changes of the extravasate. In health the vascular system practically maintains a constant blood pressure by accomodating the capacity of the blood channels to the volume of the blood. The quantity of blood that an animal may loose without be- ing seriously affected varies according to its age and health. The blood tissue of the horse has been estimated at from 1-16 to 1-12 of the total body weight. One-tenth of the esti- mated total amount of blood in the body has been withdrawn from horses used in the production of anti-toxin once every two weeks for from six to eight months without injurious results. From one-third to one-half of the volume of the blood in the body may be withdrawn at once and the animal recover. Hem- orrhage from a small vessel has little effect upon the welfare .of the body for the quantity lost is immediately restored from the 116 VETERINARY PATHOLOGY. lymph and other fluids of the body. Thus there may be a con- stant hemorrhage from the digital artery of the horse for twen- ty-four hours without injurious consequences. A sudden large loss of blood diminishes blood pressure and this results in imperfect action of the heart valves. The blood is churned back and forth, becomes mixed with air and this frothy mass accumulates beneath the valves and prevents their closure. Hemorrhage is serious when it occurs in the more delicate or the more highly organized tissues. Thus the amount of ex- travasate into the cerebrum may be very small and yet produce sufficient disturbance to destroy life, while the same amount of extravasate into the muscles of the thigh, forearm, etc., would probably not be observed. The extravasation of blood into one of the body cavities, as the pleural or peritoneal cavity, will be partially absorbed as entire blood before it becomes coagulated, the remaining un- absorbed portion will be in part disintegrated and carried out by the leucocytes and the remaining portion will finally become organized and remain as a mass of fibrous tissue. If the loss of blood is not sufficiently large to materially diminish the blood pressure and the extravasate remains free from infection there will be very little inconvenience from the hemorrhage; but if the extravasate becomes infected the outcome will be more serious. If the extravasate is into some important tissue the secondary changes will be of more consequence than when in the body cavities. There is a natural tendency for self-arrest of hemorrhage, because, 1st, blood pressure is diminished during hemorrhage and thus coagulation is favored; 2nd, the endothelium of the injured vessels becomes roughened and thus thrombic formation is favored; and 3rd, fibrinogen is liberated from vascular endo- thelium and thus the coagulation of the blood is favored, CIRCULATORY DISTURBANCES. LZ LYMPHORREAGIA: DEFINITION. (Extent of lymphatic systemi). (Lymph transudate quantity determined by blood pressure). BTIOLOGY. Ruptured vessel or space. LOCATION. Surface, because of lymph spaces and low pressure. Thoracic duct. APPEARANCE. Macroscopic. Microscopic. EFFECTS. Lymphorrhagia is the escape of lymph from injured lymph- atic vessels. The lymphatic system in general is the connecting system between the blood capillaries and the jugular vein. Lymph, the fluid in the lymphatic vessels, is that portion of the blood which passes through (or is secreted by), the capillary walls into the perivascular spaces and consists of plasma diluted, leucocytes, and usually contains considerable waste material. Lymph varies in its composition, depending upon the source, location and condition of the surrounding tissue. The lymph of the lacteal system depends upon the kind of food-material digested and the length of time since its ingestion. Etiology.— Lymphorrhagia is as a rule the result of laceration or rupture of the lymphatic channels. In rare instances it may be caused by an increased permeability of the lymphatic vessels or spaces. Because of the low pressure within the lymphatic vessels, lymphorrhagia takes place only upon surfaces or into the body cavities. Lymphorrhagia onto a surface, if long con- tinued, results in the so-called lymphatic fistula. Rupture of the abdominal portion of the thoracic duct accompanied by the escape of its contents into the peritoneal cavity produces the condition known as chylous ascites. Chylous ascites is differentiated from abdominal dropsy or ascites proper by examination of the accumulated fluid. The fluid of chylous ascites and lacteal fluid are practically identical in composition. oo x) eas 00 F Soc OS COCR OE SS OLS 00,0 S G0, 9099,P 29 0790.99 079, 6078070. On | 0.67090 2050958 Soto (06.9 89-05 00 509906 6 DIOGO COOMA 9505 9-9D Pos 0 PS 070705 90°97 Scc8 tat Dy ORO (eo) o-0 (2) As of Oo veya) (3) [a'o) 2°90 29 8 OPP F200 070% OO £2 0% OP O65; Po. 0) 3 fa) OO 7000 (5 4 oye) GBB Ooo ISS SOL TOLL Fo daGecog. Bap ROEOLS | 9G99 0 cO 8 62900, Moe 09900 [55 2 O2G (Fi OO HCO. bas 0° 3°60 000 6° BIO O86 ORF Or ah010,099 Queene: I 4 a .o) ra} 4 a 9... c Lae a © tty eS ¢ ivy Fig. 75.—Dilated blood vessel showing corpuscles spread throughout the entire lumen typical of first stages of hyperemia. tumble, and creep along over the swollen endothelial cells and finally adhere to their roughened surfaces. The continued at- tachment of leucocytes to the endothelium diminishes the cali- bre of the vessel and increases the resistance thus retarding the rate of blood flow. Oscillation.—The resistance of the flowing blood, due to the roughened endothelium of the vessels and accumulation of leucocytes becomes so increased that the propelling force is momentarily overcome. The blood in the engorged capillaries and arteries may temporarily cease flowing or it may flow toward the heart, i. e. in the reverse direction during the dias- tolic periods. This to and fro movement is termed ascillation. INFLAMMATION. 149 Stasis—The resistance may become greater than the pro- pelling force and the circulation cease for a varying period of time. This condition is denominated stasis. Exudation—Varying quantities of the fluid and of the cell- ular constituents of the blood pass through the vessels nor- mally and an increased quantity escapes through during in- flammation. The portion of the blood that escapes through the blood vessels is called exudate. The passing of the exudate | ee ee ee So ees ae ; — _ ——— ~ > ae ee eee Poms taeegs ee rr on — a ~ ne Bak = 3 oe, eo ; Sectind WES j eS SS eS Seman Se Ser = = a= Zz ae | — ae — = = Jx- —_ oy, ~ ; Fig. 92.—Wound Healing by first intention. a. Fibrinous exudate with proliferation of vessels. ec. Bottom of wound. b. Regeneration of epithelium. d. Leucocytes, Healing by granulation—This is the usual mode of wound healing in domestic animals. It differs from the healing by primary union in that there is invariably infection and suppur- ative inflammation, degeneration and necrosis preceding regen- eration. This mode of healing takes place in irregular wounds having lacerated margins and in which there is considerable de- struction of tissue and extensive hemorrhage and in wounds the margins of which are not approximated. The extravasated blood may coagulate in the wound, especially in subsurface wounds, and also in surface wounds in which the margins are 188 VETERINARY PATHOLOGY. approximated and retained by mechanical means, such as su- tures, adhesive tape, ete, “in dacerated sor capinesuriace wounds, as wire cuts, the coagulum becomes detached and drops out leaving the wound margins covered by a thin layer of coagulated serum. Within a short time after the injury is inflicted there is extensive leucocytic immigration into the tis- sues bordering the wound. The infective micro-organisms cause destruction and solution of the marginal cells until the tissue re- sistance or local immunity checks their activity. Upon the ex- posed wound surfaces there appears velvet like projections (granulations), which are capillary loops regenerated from ad- jacent vessels. Fig. 93.—Exuberant Granulation, resulting from wire cut. Between and intermingled with the granulations, regenera- tion of connective tissue takes place. Constant exposure of the a ee he PROGRESSIVE TISSUE CHANGES. 189 wound insures continued infection which retards the granula- tiot1 more or less, depending upon the extent of the infection, the degree of activity of the micro-organisms and the resistance of the tissue. The destroyed tissue in the wound is ultimately replaced with granulation tissue and, if the wound is upon the surface, epithelization proceeds as in healing. by primary union. The embryonic granulating connective tissue contracts i. e., cicatrizes about the time that epithelization occurs. Cicatriza- tion constricts and obstructs the capillary vessels, that are in excess of the normal, thus diminishing the blood supply. If ci- catrization does not occur new capillary loops (granulations) are rapidly extended producing a fungoid bloody growth, called excessive or exuberant granulation (proud flesh). The efficient regeneration and substitution of the destroyed tissues in wounds that heal by granulation is possible only in very young animals and in tissues not highly organized. To recapitulate, healing by second intention embraces sup- puration, granulation, cicatrization, epithelization and substi- tution. In some individuals the formation of fibrous connective tis- sue is continuous and there is formed large masses of cicatrical tissue known as keloids. Keloids are classified with neoplasms by some authors. EYER @©RELY, ETIOLOGY. Inherited. Antenatal. Unequal pressure. Amniotic adhesions. Post-natal. Increased nutrition. Increased function. Internal secretion. Diminished pressure. APPEARANCE. Macroscopic: Microscopic. TISSUE AREE CRED: EEE CARS: Hypertrophy literally means excessive nutrition. By usage the term has come to mean, an abnormal increase in the size of an organ or part. In a more restricted and definite sense, hy- pertrophy is a term applied to that condition resulting from an abnormal increase in the size of the essential cells of the part. Thus an increase in the size of the liver as a result of an in- creased amount of the interstitial tissue or an increase in the size of a kidney due to an accumulation of an inflammatory ex- 190 VETERINARY PATHOLOGY. udate or oedematous transudate is not an hypertrophy, al- though such conditions have been called false or pseudo-hyper- trophy. Tumors produce an increase in the size of the struc- ture affected, but this should not be confused with hypertrophy. Hyperplasia is a condition resulting from abnormal increase in the number of the cells though it is difficult to differentiate from hypertrophy. COMPENSATORY TFYPERTROPHY is the name applied to that type of hypertrophy caused by increased functional activity. Thus an increased blood pressure maintained for some time induces compensatory hypertrophy of the heart. CONCENTRIC HYPERTROPHY is a term denoting an hypertrophy of the tissues of a hollow organ, accompanied by a diminution in the lumen of the hollow organ, e. g., hypertrophy of the heart, oesophagus, intestine, or any other hollow organ in which the hypertrophied tissues occupy a portion and thus diminish the lumen of the organ. In some instances hypertrophy represents a normal, physio- logic process. The increased size of the pregnant uterus, and the enlargement of the mammae during the gestation period are examples of physiologic hypertrophy. Increased size of the heart and voluntary muscles in horses trained for racing rep- resents a physiologic hypertrophy. After the destruction of one kidney by disease or the removal of one by operation, the re- maining kidney increases in size and ultimately performs the sraciion of both, this is functional or physiologic hypertrophy and also compensatory hypertrophy. In fact practically all hy- pertrophies are physiologic, however, the hypertrophied struc- tures are abnormal, therefore the condition is pathologic. Excessive development of an entire animal i. e., giantism is designated by some as general hypertrophy. Excessive development of a part as one foot is designated local hypertrophy. Local hypertrophy is much more common than general hypertrophy. Hypertrophy may be inherited, (natural) or acquired. Ac- quired hypertrophy may be antenatal or postnatal. Etiology. INHERITED HYPERTROPHY.—The cause of inherited hypertrophy is unknown except that there is an inherited impulse to grow large. This type of hypertrophy is noted in giants. ANTENATAL HYPERTROPHY 15 usually the result of unequal pres- sure and amniotic adhesions. PROGRESSIVE TISSUE CHANGES. 191 THE CAUSATIVE FACTORS OF POSTNATAL HYPERTROPHY are, Ist, in- creased nutrition, 2nd, increased function, 3d, a stimulus, prob- ably an internal secretion, that causes the affected tissue to con- sume excessive quantities of food. Two or more of these etio- logic factors are usually evident in all cases of hypertrophy. Increased nutrition—A long continued, mild arterial hypere- mia in a tissue insures increase of the nutritive supply to the affected part and such parts usually become hypertrophic. Increased function is the prime causative factor of physiologic or functional hypertrophy. Increased function is intimately associated with increased nutrition, in fact long continued in- creased function without increased nutrition is not possible. In the production of functional hypertrophy the part must be accustomed to the extra work gradually. An excessive amount of work, assumed at once, by any structure will produce atrophy or degeneration. Cardiac hypertrophy is invariably functional as it usually is the result of valvular defects. Hypertrophy of the involuntary muscle anterior to a stricture is also functional as it results from increased muscular action to force the contents of the intestine past the stricture. Voluntary muscular hyper- trophy is also functional. Some unknown cause is active in the production of certain hypertrophic conditions. This unknown cause is probably an internal secretion, at least this would appear to be the cause of hypertrophy of the mammae and uterus in pregnant animals. That certain internal secretions are required to sustain the nor- mal balance in the growth of tissues is evident in disease of the pituitary body which frequently results in excessive develop- ment of certain parts (acromegaly). By diminishing the external pressure, experimentally, some parts have been noted to become hypertrophic. This is because of arterial hyperemia produced by diminished pressure. Appearance. Macroscopically, hypertrophied organs or parts are larger and heavier than normal and may be regular or irregular in shape. The general appearance of hypertrophied parts other than size is not usually sufficiently distinct to differentiate them from normal. Microscopic-—Renal compensatory hypertrophy is charac- terized by increased length and size of the uriniferous tubules. Hypertrophy of muscular tissue is characterized by increase in the size of muscle cells. In general hypertrophied organs or parts contain an excess of parenchymatous tissue. » 192 VETERINARY PATHOLOGY. Effects.—The effect of hypertrophy varies according to the tissue affected. There is usually an increased functional capac- ity in an hypertrophied structure. The heart musculature may become hypertrophied to such an extent that its force ruptures some important blood vessel and causes death. Increased func- tion of hypertrophied suprarenal bodies tends to increase blood pressure by the production and elimination of large quan- tities of adrenaline which causes constriction of arteries and cardiac dilation or rupture, HYPERPLASIA. DEFINITION. VARIETIES. Parenchymatous. Interstitial, EROEOGYE APPEARANCE. Macroscopic. Microscopic. USS OVS, AUAIUAE IBID). /HUMAC ICS. Hyperplasia, according to the derivation of the word, is ex- cessive formation. Hyperplasia and hypertrophy are incorrectly used interchangeably by some. Hyperplasia should be used to Tig. 94. —Hyperplasia Interstitial Testieular Cells. a. Interstitial hyperplastic tissue. b. Seminiferous tubules not fully developed designate the condition resulting from an abnormal increased size of a part due to an increase in the number of cells of the part. Accepting the last definition, hyperplasia may be due to an increased number of parenchymatous cells, or an increased PROGRESSIVE TISSUE CHANGES. 193 number of interstitial cells the two types being called parenchy- matous hyperplasia and interstitial hyperplasia respectively. Parenchymatous hyperplasia and numerical hypertrophy are sometimes used synonymously. Interstitial hyperplasia is prac- tically the same as fibrous hyperplasia. i Parenchymatous hyperplasia is not of common occurrence It is usually either inherited or congenital. Interstitial hyperplasia is quite common as it is usually evident in chronic inflammatory tissues and it is also occasionally observed in structures affected with functional fibrosis as is ev.- dent in the liver of animals afflicted with disturbances of the cardiac valves. The descended or scrotal testicle of single cryp- torchids is usually enlarged because of an increased amount cf parenchyma and hence is an example of interstitial hyperplasia. Etiology, The cause of parenchymatous hyperplasia is unknown. Inter- stitial hyperplasia 1s produced by the long continued action of mild irritants or other substances that produce over stimulation. Fig. 95.—Pen drawing of an Hyperplastic Ureter, ox, natural size. Appearance. Macroscopic—Parenchymatous hyperplastic structures are regularly or irregularly enlarged and are heavier than normal. Interstitial hyperplastic parts vary in appearance according to the amount of hyperplastic fibrous tissue. The part may vary 194 VETERINARY PATHOLOGY. from normal to dense, hard, pale irregularly lobulated masses of fibrous tissue. Microscopic-—Parenchymatous hyperplastic structures have the same appearance microscopically as sections of normal tissue. Sections of tissue affected with interstitial hyperplasia con- tain an increased quantity of fibrous tissue which may be readily recognized microscopically especially if the section is stained with hematoxylin and picro-fuchsin. Effects. A part affected with parenchymatous hyperplasia will have an increased functional capacity. The effects of an increased functional capacity of a structure depends upon the part in- volved, and may or may not be injurious to the animal in which if OCEUTS. Interstitial hyperplastic structures have an increased quantity of fibrous tissue and usually a diminished amount of parenchy- matous tissue and a diminished function. Interstitial hyper- @ 2 is a Pi « 1 & Eo” 2Gq ree. g¢ mee es ee +2"- Epithelium ---+++ ...-+- fLeiomyoma Ra A oo Rec hOrIOOIrOn or | Rhabdomyoma ..+++ esses see sees renee Adult Tissue J Muscular-myoma Lymphangioma «+--+ --.+.+es ere eeeee Hemangioma .-+-+++ tere eee reece eee S | Nervous-neurroma 3 L ra © ( Round Cell -y . Spindle Cell Connective-Sarcoma | Myeloid Cell Endothelioma | Placentoma Vascular-angioma { Embryonic Tissue - Garcinomameoeese ec Hypernephroma | Epithelium | Adenoma «--+++++++: | . Epithelioma «++++++- J J FIBROMA. Fibromata are tumors composed of adult fibrous connective tissue. They occur in all animals. The skin and subcutaneous areolar tissue is their most frequent location, but no tissue 1s exempt. They are frequently found in the region of the sternum of the horse and ox, in the ovary and uterus of the cow, and in the perineal and elbow regions of the dog. In the skin and sub- cutaneous tissue they usually appear as loose, circumscribed, nodular growths. Some fibromata have no well defined border or line of demarcation but are apparently diffused through the tissue. This type, however, is somewhat rare, and possibly they are not fibromata. They may become so large that their pres- sure produces atrophy, degeneration or necrosis of the skin cov- ering them, or the surface epithelium may produce sufficient new tissue to compensate for the increased surface. These tu- 280 VETERINARY PATHOLOGY. mors are usuaily single, that is, only one tumor occuring in the individual; but they may be multiple. Multiple fibromatosis is occasionally observed in the subcutaneous tissue of horses. They are variable in size, being so small in many instances that they are not observed in an ordinary examination. Si ay ad ce ROWS SS ee ae Be cn SS eae S&S ae GS 3 SS, CT A Soke fi C= : ¥ : OE a eS 33Y X00. Fig. 128,—Section of Myxoma from the orbital fossa of a horse, showing stellate cells. ee ee TUMORS. 285 which the cell processes are apparently continuous with the pro- cesses of adjacent cells. Myxoma cells have an oval nucleus and the spaces between the cells and cell processes are filled with mucus, which appears as a stringy, gray substances that stains red with eosin. Myxomatous cells produce both kinds of fibres, 1. e., glia and collagen fibres. The collagen fibres are more or less separated from each other by a varying quantity of fluid containing mucin. Myxomata are prone to degeneration, result- ing in the formation of a cyst, or the fibrous capsule may become eroded, allowing the degenerated contents to escape into the sur- rounding tissue or upon a surface. In the latter case the degen- erated contents is usually absorbed. Cicatricial tissue is usually produced in the cavity or space occupied by the myxoma. Sub- surface, myxomatous, degenerated areas may become infected, resulting in abscess formation. Clinically, myxomata are benign tumors. They grow slowly by interstitial expansion, do not recur when removed, and ex- tend only by continuity or contiguity. These tumors are differentiated from muccid degeneration, as the latter contains no stellate cells, and there are usually some of the cells present in mucoid degeneration that are normally present in that area. Clinically, it may at times be difficult to distinguish between mucus retention cysts and myxoma, but by the exploring needle the contents of the cyst may be evacuated and thus the nature of the mass will be determined. CHONDROMA. A chondroma is a cartilaginous tumor. They occur in cattle, sheep, dogs, horses and fowls. They are found most frequently in the location in which cartilage is normaliy found. The ster- num seems to be a favorite location for their development, prob- ably because of the frequent injuries of the sternal cartilage due to the fracture of ribs and other injuries. They not infrequently occur in other bones, possibly developing from islands of cartil- age that have not ossified, or from marrow or periosteum. They also occur in glandular tissue as the thyroid, parotid, ovary and testicle, and a few cases of chondromata of the lung have been reported. These tumors appear as hard, nodular, well-defined growths, unless they are undergoing degeneration. In this case they may be of the nature of cysts, or if their capsule is ruptured, they may be soft, spongy, diffuse masses. They are variable in size. A chondroma weighing 12 kilograms (26 1/5 Ibs.) was obtained 286 VETERINARY PATHOLOGY. from the sternum of a sheep killed in a Kansas City abattoit. Another about the size of a pigeon’s egg and attached to the sternum of a small hen was found by a city meat inspector. Prof. G. H. Wooldridge reported a case in the “Veterinary Jour- nal” in which there was a chondroma 4 or 5 times as big as a man’s fist between the humerus and scapula and chest wall of a cat. Their shape is very irregular, but they are most frequently oval. As a rule they have a regular surface, though they may be lobulated. They are usually separated from the surrounding tissue by a fibrous capsule, but they may be firmly adherent to the adjacent tissue. In cutting, the tumor gives a resistance sim- ilar to cartilage and they may be gritty because of calcification or ossification. The ablated tumor is bluish-white if it is a pure chondroma. Degenerated areas will vary in color according to the kind and degree of the degeneration. Necrotic centres appear dull gray or yellowish-white and white if calcified. If the tumor is mixed the color will vary according to the contaminating tumor tissue. Chondromatous tissue is composed of cartilage cells and an intercellular substance. The cells are irregular in size and shape and the number found in each lacuna is more variable than that in normal cartilage. The size, shape and arrangement of cells in different areas in the same tumor is variable. The cells are fre- quently degenerated, the nucleus fragmented and the cell mem- brane ruptured, allowing the cells to fuse as a homogeneous Fig. 129.—Section of Chondroma from sternum of a sheep, showing lacunae with inclosed cartilage cells. a a le te Ae ir” ae lee TUMORS. 287 mass. The lacunae are not so distinct as those in normal cartil- age, and their capsule may be absent. The intercellular substance is usually homogeneous, as in normal hyaline cartilage, or it may be fibrous, as in normal fibro-cartilage or elastic cartilage. The in- tercellular substance becomes fibrous towards the margin of the growth and finally forms a perichondrium. The cells may be arranged in rows near the perichondrium, but they are more likely to be irregularly distributed. The microscopic appearance of a degenerating, necrotic or mixed chondroma depends upon the kind and extent of the condition existing. Clinically, chondromata are usually benign, but they may be- come malignant because of their extent. Some surgeons have recorded csses of metastatic chondromata. These tumors are frequently lobulated and may be multiple. They have little ten- dency to recur when removed. LIPOMA Lipomata are tumors composed of adipose tissue with a con- nective tissue framework supporting the vascular supply. They occur quite commonly in the horse, ox, and dog, but none of the domestic animals are exempt. They usually develop where adi- pose tissue normally exists, as the subcutaneous tissue, submu- cosa and subserosa, omentum, ete. They may also occur in tissue that contains no fat, as the liver, kidney and even the brain. They occur most frequently in the subcutaneous tissue in the horse; in the intestinal and omental subserosa of the ox and hog; in the subcutum and conjunctival submucosa in the dog, and in the uterine submucosa of the sheep and the cow. Lipomata are usually circumscribed, but they may be diffuse. The accompanying cut is from a photograph of a two-year-old colt in which there is shown a diffuse subcutaneous lipoma of the left hind leg. These tumors may become enormous in size in the horse and ox, some cases having been reported of lipomata as large as a wash-tub and weighing 30 to 70 kilograms (66 to 154 lbs.). In consistency, these tumors may be firm and dense or soft and flabby. They are usually surrounded by a fibrous capsule and in section those from the peritoneum and omentum gre yellowish or white in color. Peritoneal, omental, submucous and subcutaneous lipomata have a smooth surface; intestinal lipomata are usually lobulated. Bands of connective tissue may divide the tumors into lobes or lobules or the connective tissue may be diffuse throughout the entire structure. In cutting a lipoma the resistance varies accerding to the quantity of fibrous connective tissue it contains. If osmic acid is applied to the free 288 VETERINARY PATHOLOGY. surface of the gross specimen it stains the adipose areas black but has no effect upon other tissue. Occasionally groups of adi- pose cells become necrotic and calcify, thus forming gritty areas. Complete necrosis with sloughing or calcification is not rare in the larger lipomata. Fig. 130.—From photograph taken 6-20-’7 of a colt affected with a Subcutaneous Lipoma. Photograph presented by J. Il MeNeil. TUMORS. 289 Microscopic sections of lipomatous tissue closely resemble normal adipose tissue, except that the cells may be larger and perhaps more irregular in shape. As in normal adipose tissue the adipose cells are supported by connective tissue cells and fibres. The application of Sudan III and osmic acid gives further proof of the composition of the cells. Lipomata may be multiple but they are typical benign tumors, though death may result from the mechanical effects produced Fig. 131.—Section of a Lipoema from omentum of an ox, showing framework. of adipose cells, by them. They do not form metastases. Subserous lipomata pro- duce volvuli which terminate fatally in horses. Large periton- eal or omental lipomata of the ox and dog frequently cause suffi- cient displacement of the abdomina! organs to materially de- range their function. Subcutaneous carpal lipomata in the horse may become so large that they mechanically interfere with loco- motion. Lipomata may have a fibrinous infiltration and organ- ization resulting in lipomatous elephantiasis, 290 VETERINARY PATHOLOGY. OSTEOMA. An osteoma is a tumor composed of osseous tissue. Pure osteomata are not common. They occur most frequently in re- lation to bones and usually at the union of osseous tissue devel- oped from different ossifying centres. These tumors are quite common in mules, appearing as projecting pedunculated masses attached io the inferior maxilla. More rarely they are found in other organs, as the lung, parotid gland, mammary gland, etc. Fig. 132.— Fedunculated Osseous Tumor Mavxilla. Horse. These tumors are usually small, rarely becoming as large as a cocoanut. They are hard, nodular masses that are frequently lobulated and usually firmly attached to the surrounding tissue. It is possible that they are developed from osseous cells which have been misplaced in bone formation or from the osteogenetic layer of the periosteum. When they develop adjacent to pre- existing bone the periosteum or endosteum surrounds them. Those osteomata developing in other structure than bone are surrounded by a distinct membrane which is usually very sim- ilar to periosteum. QOsteomata may be classified as: (1) hard, ivory or eburnated, and (2) soft, spongy or cancellated. Either of the foregoing classes may be homologous or heterologous. Homologous osteomata occur in bony structures and may be an exostosis or an enostosis. Heterologous osteomata occur in other tissue than bone. Hard, ivory or eburnated osteomata are structurally very similar to the compact osseous tissue of a long bone. Haversian systems may be present or they may be absent. If the Haversian systems are present they are irregularly arranged and are ap- proximately perpendicular to the surface of the related bone. If TUMORS. 291 the Haversian systems are absent the tumor is composed of superimposed lamellae like the outer circumferential lamellae of the shaft of a long bone. Soft, spongy or cancellous osteomata are surrounded by a periostoid membrane. In structure they are similar to cancellous osseous tissue. The marrow spaces may be occupied by tissue that is structurally identical to red marrow or they may be filled with sarcomatous tissue, fibrous connective tisssue, etc. The blood vessels are usually normal in structure and their distribu- tion is through Haversian canals in the hard osteoma or the spaces in the soft osteoma. Osteomata are invariably single; do not recur when removed; have no tendency to form metastases; and hence are benign. They should be differentiated from (1) ossification of inflam- matory new growths as ringbone, spavin, myositis ossificans, etc.; (2) hyperplasia of osseous tissue; (3) ossification of tumor tissue as fibromata, chondromata, etc.; (4) metaplasia in which osseous tissue is the end product; (5) calcification. GLIOMA. A glioma is a tumor composed of supporting cells (neuroglia cells) of the tissue of the central nervous system. Neuroglia tissue occurs in two forms, as ependymal cells lining the neural canal and the ventricles and as glia cells which-are derived from the ependymal cells and act as a supporting framework of the central nervous system. Gliomata are of two types, depending upon the type of cells composing them, viz., spider cell glioma and mossy cell glioma. Gliomata have been observed only two or three times in the domestic animals. They usually have their origin in the gray matter near the central canal of the spinal cord or in the gray matter of the cerebrum. They do not become large and they are usually not encapsulated. They are composed of cells that are very similar to normal neuroglia cells. The glioma ceils may be slightly larger than neuroglia cells but they have the fibre-like processes characteristic of them. These tumors do not form metastases but are likely to produce a fatal termination by pressure upon nerve centers. ODONTOMA. Odontomata are tumors composed of dental tissue and usu- ally occur in connection with teeth, particularly the superior molars. Odontomata are of frequent occurrence, the majority of dental diseases in two to five-year-old horses being due to 292 VETERINARY PATHOLOGY them (Williams). Facial bulging is a common symptom of them and there may be an excessive mucus discharge from the nostrils. Cystic odontomata may produce super-resonance, which is useful in differentiating them from empyema of the facial sinuses. These tumors are derived from the enamel organ, dentine papilla, or the tooth follicle. Their derivation to some extent determines their structure. Those derived from the enamel organ are composed of an enamel covering and in some cases the entire odontoma is enamel. Dentine is usually the pre- dominating tissue in those derived from the dentine papilla. From the tooth follicle there are usually formed cystic odonto- mata, although they may be fibrous or may contain ossified cen- tres and cementum. Their structure varies considerably and it is not rare that all of the above structures are represented in one odontoma. In size, odontomata vary from microscopic masses to irregu- Fig. 133.—Photograph of an Odontoma of the interior maxilla of a horse, TUMORS. 293 lar bodies. Their shape and color are as variable as their size. Epithelial or enamel odontomata are the highest in the scale of hardness of all tumors. Other types of odontomata are soft. Cystic odontomata may be single or multiple, as many as three hundred having been observed in a single follicular tumor of this type. They may grow very rapidly but more frequently they develop slowly. They have no tendency to form metastases. Degeneration is common in those developing from the tooth follicle. Clinically they are benign but may cause fatal termina- tion mechanically or from infection. According to the derivation Sutton describes four classes of odontomata as follows 1. Those derived from the enamel organ or epithelial odonto- mata. They usually appear as irregular masses covered with enamel. They may contain cystic cavities separated by enamel partitions. Epithelial odontomata are usually surrounded by a firm capsule, and in some instances appear to have had their origin from a mucous membrane. Miscroscopically they are found to be composed of ename! cells and irregular columns of epithe- lial cells forming alveoli. The epithelial cells vary in shape from columnar to the stellate or typical progenitors of enamel. These tumors occur in most of the domestic animals and usually in early life. Two epithelial odontomata were obtained from the left maxillary sinus of an aged horse used for dissecting pur- poses. These odontomata were completely enclosed in an osse- ous mass, the maxillary sinus being completely filled by the new growth. The facial bones were slightly bulged. The osseous formation surrounding the odontomata and the thickening of the facial bones indicated that considerable time had elapsed since their formation. 2. Those derived from the tooth follicle. Depending upon the nature of the neoplasm this group may be further subdivided into follicular and fibrous odontomata, cementomata and com- pound follicular odontomata. Follicular odontomata result from hyperplasia of the tooth follicle tissues which thus prevents the normal eruption of the tooth. They may appear as simple or multiple cysts. Their walls may be calcareous or osseous but they are more frequently membranous. The cysts are usually subdivided into many com- partments, the cavities of which are lined with epithelium. This lining epithelium secretes a viscid fluid, the accumulation of which is responsible for the enlargement of the cysts. They occur in sheep, hogs and horses. Fibrous odontomata are produced by a marked increase of 294 VETERINARY PATHOLOGY. the enveloping fibrous capsule of the follicle. The hyperplastic fibrous tissue usually fuses with the cementum, and the entire mass may later become calcified or ossified. These odontomata are most common in ruminants, goats especially being affected. They are prone to occur in animals afflicted with rickets. Cementomas (Osteocystoma capsulare dentiferum) are formed by ossification of excess tissue developed around the tooth follicle. The hyperplastic cementum may include several tooth germs. They appear as masses of cancellous or spongy bone and are structurally very similar to cementum, being com- posed of irregular spaces surrounded by osseous tissue contain- ing branched lacunae. They are most common in horses, occur- ing most frequently in connection with the incisor teeth. Fig. 134,—Enpithelial Gdontoma, Compound follicular odontomata result from the ossification of irregularly located areas of the tooth follicle tissues, thus leaving intervening areas of fibrous tissue. The ossified masses are designated denticles and they may be very numerous, as many as three hundred having been observed in a single tumor. The intervening tissue usually degenerates and becomes of a liquid consistency. Thus the tumor appears as a cyst containing many cavities. The denticles vary in size and consistency. These tumors have been observed in the goat, sheep, ox, and horse, TT ele: agian ey aS te ES TUMORS. 295 3. Radicular odontomata are those derived from the dental papilla, developing from the roots of a tooth after the crown has formed. They appear as bony masses and are frequently enclosed within the maxilla. Structurally, they consist of den- tine and cementum, the dentine usually being surrounded by a cemental capsule. They are occasionally observed in domestic animals, being most common in boars. 4. Composite odontomata are composed of varying amounts of irregularly arranged enamel, dentine and cementum. A single tumor may contain several teeth fused into one mass. Their structure varies with the amount of each of the above named constituents they contain. Thus they may be almost entirely enamel or contain a very little enamel. They may be solid and massive or cystic. They are very likely to cause suppuration and necrosis of the adjacent tissues. This type of odontomes occurs more frequently in the horse. Dentigerous cysts are more properly classified as a type of teratomata and will be discussed with that group of tumors. NEUROMA. Neturromata are tumors composed of nerve tissue. They are exceedingly rare. They occur in connection with ganglionic cells and most frequently those of the sympathetic ganglia, al- though they may occur in the brain. They appear as nodular growths varying from the size of a pin head to that of an apple They are gray or white in color, rather firm, and usually sur- rounded by a capsule. Irregularly shaped ganglionic cells inter- posed with some nerve fibres constitute their minute structure. These tumors should be differentiated first from the so-called “amputation neuromata,’ which are simply an entangled mass of regenerated axones and are not tumors; second from fibromata that develop from the perineurium or endoneurium of a nerve trunk. ; Neuromata may be multiple but they are usually benign. ANGIOMA. These are vessel tumors that are developed independently of pre-existing vessels. But it is frequently impossible to deter- mine whether the mass of vessels is a result of excessive growth of the pre-existing vessels (hyperplasia) or whether they are newly-formed vessels. ; Possibly angiomata should be discussed under the caption of 296 VETERINARY PATHOLOGY. endotheliomata as it has been thought by some that the endothe- lium is the only neoplastic portion of an angioma. This group is composed of (1) hemangiomata. (2) lymphan- giomata. Hemangiomata are blood-vessel tumors. In the human they are found most frequently in the skin and may occur in the skin in domestic animals, but are not often observed there because of the pigmentation of the skin. They are found most frequently in the liver and the spleen of the ox, dog, horse and sheep. An occasional case is observed in the subcutaneous tissue of the horse. Hemangiomata may be subdivided into four varieties. Hemangioma simplex (Capillary telangiectases, nevus, birth mark) is a tumor in which there is an excess of capillary vessels that are considerably enlarged or dilated. The vessel wall is usu- ally altered in structure, the endothelial cells being larger and the perivascular tissue more dense. These are quite common in the liver of the ox where they appear as irregular blood spots, red or purplish in color. oe aly, jooede se ae 4 yh laa og oe re —s : = if SN /3 399.6 = fe a, > = LS erence he eZ Lf CLEP EEN N if Se ft ay, - ek Hf f a ES ie COPS UE Le, De Leg etek SEE Se AT Fig. 135. —Haemangioma Simplex. a. Large capillaries engorged with blood. b. Liver cells. Cavernous hemangioma (hemangioma cavernosum) is a tumor composed of spongy tissue similar to erectile tissue. The caver- nous spaces are filled with blood, thus coloring the tumor red or bluish-red. These tumors are found most frequently in the liver and spleen. An ox liver containing cavernous spaces, each as large as a hen’s egg and containing parietal thrombi, has been 55 observed. A lobulated enlargement in the spleen of a dog was rs TUMORS. 297 found to be a cavernous hemangioma. The spaces in cavernous hemangiomata are lined by endothelium that is supported by a very limited amount of white fibrous connective tissue, yellow elastic tissue being practically absent. Fis. 136.—Photograph of spleen of dog affected with an Hemangioma Carvernosum, Hemangioma hypertrophicum is a blood-vessel tumor composed of masses of relatively small vessels, in which the vessel walls are hypertrophied. One of these tumors occurring in the subcu- taneous tissue of the metacarpal region of a horse has been observed. It appeared as a mass beneath the skin and was about the size of a hen’s egg. Pulsations could be observed and by palpation they were quite distinct. The tumor when removed was a tangled mass of blood-vessels with comparatively small openings. Microscopically, the vessel walls were found to be hypertrophied. The vessels were held together by fibrous con- nective tissue. Cirsoid aneurisms are tumors composed of dilated and enlarged 298 VETERINARY PATHOLOGY. tortuous arteries. This variety of hemangiomata is not common in the domestic animals. Lymphangiomata are tumors composed of newly-formed lym- phatic vessels. These tumors are not common; in fact, only one Fig. 137.—Section of Hemangioma Hypertrophicum, showing an increase in the number of the vessels and an hypertrophy of their walls. or two cases have been reported by veterinarians. The tumors may be conveniently divided into capillary and cavernous. Angiomata are usually benign tumors, although by rupture they. may produce fatal hemorrhage or lymphorrhage. MYOMA. Myomata are muscle tumors. They are divided into- two classes: 1. Leiomyomata or the smooth muscle tumors. -2. Rhabdomyomata or the striated voluntary muscle tumors. My- omata, found occasionally in the human, are rare in the lower animals. bey TUMORS. 299 Leiomyomata are found most frequently in those locations in which involuntary muscle tissue normally exists, as the uterus, bladder, intestine, etc. They are nodular or diffuse, dense, pale pink masses appearing very similar to fibromata. Microscopic- ally they are composed of miscellaneously arranged involuntary muscle cells. They differ from fibromata in that the muscle cells are thicker and usually not as long as the fibres of fibromata. Frequently they are combined with fibromata forming a leiomyo- fibroma, making the diagnosis more difficult. LLeiomyoma cells may be very similar to the cells of a spindle-celled sarcoma, but Fig. 138.—Leiomyoma, small intestine, mule. the nuclei of the former are long and rod-shaped while those of the latter are oval in shape, a characteristic usually sufficient for diagnosis. The cytoplasm of the leiomyoma cells stains densely with acid stains. Rhabdomyomata have been found in the kidney, ovary and testicle. They are probably the result of the development of misplaced embryonic myoblasts. These tumors are usually pale in color. In microscopic section the cells are irregularly striated, 300 VETERINARY PATHOLOGY. and are variable in shape and arrangement. These tumors are benign. Fig. 139.—Leiomyoma. a. Smooth nucleus cell, showing nucleus. SARCOMA. A sarcoma is a tumor composed of embryonic connective tissue cells. Sarcoma occasionally succeed an injury and are common where globin is prevalent, as in muscle, bone, etc. The cells have no tendency to become mature but constanly appear as undiffer- entiated mesoblastic embryonic cells. Sarcomata are of frequent occurrence in all domestic animals. They have no predilection for tissue or location, and are variable in size and shape. They may be circumscribed but are more frequently diffuse. Metastases are frequent in the lungs, liver and kidney. Metastatic sarcomata are usually circumscribed. TUMORS. 301 Sub-surface sarcomata may produce necrosis of the surface tis- sue, the tumor projecting as a red, granular mass, which appears very similar to exuberant granulation. The surface tissue may not be destroyed, in which case the tumor appears as a sub-surface nodule or diffuse mass. Some sarcomata are encapsulated and are easily enucleated, but the malignant varieties have no cap- sule and it is impossible to differentiate the surrounding tissue from that of the tumor. Sarcomatous tissue may be soft and spongy or hard and dense, depending upon the extent of the intercellular substance and the kind of cells composing it. In color they vary from gray or white to pink and they may be mottled, depending upon an excessive amount of blood or hemorrh- agic extravasate, pigmentation, or necrosis. The microscopic appearance varies with the different varieties, but in general they are found to be composed of embryonic cells: Fig. 140,—Photograph of a horse affected with Sarcoma of the Mediastinum result- ing in obstructed circulation. (a) Oedema inferior thoracic reg:on. (c) Subcutaneous veins. -0) Jugular vein engorged with blood, . 302 VETERINARY PATHOLOGY. having a limited amount of intercellular substance. The cells may be round, spindle, or myeloid, and the intercellular substance may be mucoid, fibrous, cartilaginous or osseous. The cells contain a large centrally located ovoid nucleus, which occupies practically the entire cell body. Mitotic figures are common in rapidly growing sarcomata. Frequently there are multipolar mitotic figures indi- cating the possible division of a cell into three or more daughter cells. Karyolysis or nuclear fragmentation is well marked in those cells that are centrally located in the tumor, and especially in degenerating centres, and in the cells of sarcomas that are not Vig. 141,—Section of tumor, showing mottled appearance, a result of Necrotic centrea z TUMORS. 303 growing rapidly. The portion of the cell body not occupied by the nucleus is composed of undifferentiated protoplasm. In appearance the intercellular substance varies according to its composition. An abundance of capillaries and small blood vessels are found in sarcomata. These may be normal in struc- ture or they may be infiltrated with sarcomatous tissue, and, in some cases, the blood flows through channels formed by sar- coma cells. Hemorrhage is of frequent occurrence in sarcomata. The blood vessels have no regularity in their distribution, a structural peculiarity frequently resulting in degeneration and necrosis. Lymphatic spaces and vessels are absent in sarcomata, excepting lympho-sarcomata, unless they are entangled during the development of the tumor. Nervous tissue has not been demonstrated as a distinct new growth in sarcomas. There are usually many leucocytes and frequently some plasma cells in sar- comatous tissue. The plasma cells may produce the intercellular structures of sarcomas or they may become adult connective cells and produce fibrous connective tissue. Fig. 142.—Round cell Sarcoma. The rapid development and the irregular distribution of blood vessels predispose sarcomas to destructive processes. Mucoid degeneration frequently occurs and may result in the complete destruction of the tumor. Necrosis is also quite common, and suppurative conditions are not rare. If the normal tissues are eroded, exposing the tumor tissue, septic infection is common and sometimes results fatally. This group of tumors may be «lassified, according to their 304 VETERINARY PATHOLOGY. cellular elements, as (1) round-celled sarcomata, (2) spindle- celled sarcomata, and (3) myeloid-celled sarcomata. Round-cell sarcoma. ‘This tumor is composed primarily of round cells (spherical cells) and is rather common. They de- velop in any tissue and are, as a rule, the most malignant tu- mors of this entire group. They are soft, spongy, and usually quite vascular, and, as a rule, are not encapsulated. Structurally the cells of this variety approximate the embry- onic epithelial cells more closely than do those of any of the other types. According to the size of the cells two classes may be recognized, viz.: small and large. There is, however, no dis- tinct line between the two classes. The small, round celis are about the size of lymphocytes while the large, round cells are as large and sometimes much larger than mononuclear leuco- cytes. The nuclei of this type of sarcoma cells are, relatively, much larger than the nuclei of lymphocytes or leucocytes. In fact, the nucleus occupies practically the entire cell body. The intercellular substance is very limited and is usually mucoid or reticular. Blood vessels are usually numerous, and their walls are frequently formed by sarcomatous cells. Metastatic growths are frequently of this type. The cut on page 274 is from a pho- tograph of the lung of a horse, showing metastatic round-celled Fig. 143.—Photograph of sheep’s heart, showing a lympho sarcoma of the pericardium. TUMORS. 305 NOLO) Oy?" Sestiees oGe) Fig. 144.—Section of a Lympho Sarcoma of a dog’s omentum, showing the lymph vessels and sarcomatous tissue. sarcomata. The primary tumor involved the eye-ball and finally destroyed the soft structures of the entire orbit. In this case two or three metastatic tumors were observed in the liver also. The cut] one-page 30l sis-arsphotecraph of a horse in which there was an extensive sarcomatous formation in the thoracic cavity involving the mediastinum, pericardium, pleura and some smaller nodules in the lung. (The lung nodules were, no doubt, metastatic formations.) Because of their tendency to form metastases and the rapid peripheral infiltration these tu- mors usually cause a fatal termination. Lympho-sarcomata are a variety of round-celled sarcoma, and are called lymphomata by some authors. They are quite com- mon in all domestic animals. These tumors have their origin in lymphoid tissue and are extended by the lymph. Two cases have been studied in the ox in which the primary lesion was in the wall of the abomasum. One case of generalized lymphosar- comatosis has been observed in a chicken, A pericardial lym- 306 VETERINARY PATHOLOGY. phosarcoma was found in a post-mortem examination of a sheep. An omental lymphosarcoma in a dog was reported in the Ameri- can Veterinary Review, December, 1905. The color, consistency and size of lymphosarcomata is quite variable. Microscopically these tumors are found to be composed of lymphoid cells, the tumor cells being supported by stellate cells. Lymph vessels are usually quite numerous and their structure is similar, if not identical, to that of normal lymph vessels. The stellate supporting cells and the presence of lymph vessels are the distinguishing characteristics of lymphosarcomata. There is no leucocytosis in animals affected with lymphosarcomata, while in those affected with leukemia leucocytosis is well marked. These tumors are malignant. They form metastases through the lymph and blood channels. They are usually surrounded by a very thin capsule. Fig. 146.—Photograph of a muie affected with a spindle cell Sarcoma of the eyelids, 1. Granular denuded tumorous surface. 2. Granular fungoid tumorous mass. TUMORS. 307 Spindle-Cell Sarcoma.—Tumors of this variety are composed of spindle-shaped cells. They are more firm and dense than the round-cell sarcomata. These tumors are not rare, occurring most frequently in connection with the skin or subcutaneous tissue. Some of the resistant and incurable cases of fistulous withers are spindle-celled sarcomata. A collar boil that did not respond to treatment was found to be a spindle-cell sarcoma. These tumors are common in the eyelids of horses and mules and are sometimes quite persistent regardless of surgical interference. The Fig. 146.—Section from spindle cell Sarcoma of a mule’s eyelid. and are sometimes quite persistent regardless of surgical inter- ference. The cells vary from short, thick fusiform cells to elong- ated fibre-like cells. Spindle cells are more matured than the cells of round-cell sarcoma. Round cells have no tendency to become spindle cells, neither do spindle cells become either round cells or matured connective tissue cells. The cells in spindle- cell sarcomata have no definite arrangement but extend in all directions. In microscopic section some cells are cut trans- versely, others obliquely, and still others longitudinally. The nucleus is centrally located, is usually spherical or oval in shape, and is not as large in proportion to the size of the cell as that of the round cells. Some have suggested a classification of this 308 VETERINARY PATHOLOGY. group into large and small-celled varieties. The cells are usu- ally held together by reticular connective tissue. This may be demonstrated in sections in which the sarcoma cells have been dissolved out by acetic acid. The density of the tumor depends upon the relative quantity of protoplasm the cells contain. and the amount of intercellular material. A tumor composed of short, thick spindles is less dense than one composed of fibre- like cells. Blood vessels usually have normal vessel walls and are not as numerous as they are in round-cell sarcomata. © ae 5» OO SO Bais SOB OS 08 wey sae Oe 8 © eGe < Sar 86 eee 8 @ ant Fig. 147.—Myeloid or Giant cell Sarcoma of the Humerus. a. Giant cells. b. Sarcoma cells. These tumors are usually encapsulated, rarely form metas- tases and are, in general, not as malignant as the round-cell variety. They may be mistaken for fibromata, but a careful study of a microscopic section is usually sufficient for differen- tiation. Fibromata contain no elements that appear like trans- verse sections of spindle cells. Leiomyoma may be differen- tiated by the shape of the nucleus and the selective action of stain as picrofuchsin. Myeloid-Cell Sarcoma (Giant-Cell Sarcoma).—This is a variety of sarcoma characterized by the presence of myeloid or large multinucleated giant cells (myeloplaxes). Giant cells of at least two types occur in tumors, one of which results from multi- ple mitosis and usually indicates rapid growth and may occur in a variety of different tumors. The second type of giant cells is due to TUMORS. 309 the fusion of invading endothelial leucocytes and occur most fre- quently in bone tumors. The latter are therefore not true tumor cells, although they usually receive the name. Surgeons and patho- logists frequently find myeloid sarcomata in man, but they are rare in domesticated animals. They are invariably found in relation to, or in connection with, bone-marrow, or more rarely in relation with periosteum. They frequently contain cartilaginous, osseous or calcareous centres. Ball in “Journal de Med. Vet., et de Zoo- techny de Lyon,” reported a case of giant celled sarcoma affected the right front foot of a 6 year old cat. Microscopically, they are composed of myeloid cells and round or spindle cells. The myeloid cells are the distinguishing elements of this variety of sarcoma. hee ZevoOle thie myeloid cells is variable, frequent- ly being 80 to 100 microns in diam- eter and with an irregular outline, varying in shape from a sphere to an elongated mass. Their protoplasm may be quite gran- ular vor-a lim.o%s't clear. “hey shave many nuclei—150 being observed in Olle sCelliee a terse nuclei have no de- finite arrangement but occur miscel- laneously through- out the entire cell body. The round and spindle cells are Like those Fig. 148.—Photograph of horse's head affected with occurring in round mixed cell Sarcoma, ° and _ spindle-cell sarcoma. There may be an excess of one or the other or they may be equal in number. The intercellular substance varies from mucoid to calcareous in nature. There is usually an exces- sive blood supply, the blood vessel walls being usually normal 310 VETERINARY PATHOLOGY. in structure. Degeneration as well as necrosis and calcification are of frequent occurrence in myeloid sarcomata. These tumors may not be completely encapsulated, though there is always a tendency for them to be circumscribed. They are the least malignant of all sarcomata. They rarely form me- tastases. Mixed-Cell Sarcoma.—This is a variety of sarcoma charac- terized by the presence of variously shaped cells, as round, spin- dle and even stellate cells. This variety is not as common as either the round-cell or spindle-cell varieties. They have been observed in the horse, hog and ox, but they doubtless occur in all domestic animals. They affect bone, glandular tissue, and meninges of the brain, in fact, no tissue is exempt. An inter- esting case of mixed-cell sarcoma of the inferior maxilla of a horse was described in the December Veterinary Review, 1905. The tumors frequently degenerate and become necrotic. Mi- croscopically they are composed of round cells and_ spindle cells that are identical in structure with those described in the discussion of round-cell and spindle-cell sarcomata. Stellate cells may be present, and are very similar in structure to mucoid connective tissue cells. The cellular elements are supported by reticular tissue or by fibrous connective tissue. The number of blood vessels is variable. There is an excess of vessels in those Fig. 149.—Photograph of Maxilla of horse shown in Fig. 162, showing 3 bony points; the remainder of the maxilla being completely destroyed py the sarcomatous tissue, TUMORS. Sl made up principally of round cells and in those that have a lim- ited amount of intercellular substance. The vessel walls may be normal or they may be composed of sarcomatous tissue. De- generate or necrotic changes in the tissue necessarily alter the microscopic appearance. Fig. 150.—Section of a mixed cell Sarcoma of the inferior Maxilla of a horse, These tumors are usually diffuse; that is, they are not encap- sulated. They form metastases, and hence are malignant. Alveolar Sarcoma.—This is a sarcoma characterized by the arrangement of the sarcoma cells into groups or nests, and is occasionally found in domestic animals, especially in the ox and hog. The reproductive glands, ovary and testicle, are the struc- tures most frequently invaded by them. They may become quite large. An alveolar sarcoma obtained from the ovary of a heifer weighed 15 kilograms (33 Ibs.) and was about 20 cm. (8 in.) 1n diameter. Microscopically the cells are usually round, although they way be spindle-shaped. The stroma of the tumor is made. up of SZ, VETERINARY PATHOLOGY. two portions. One portion is usually composed of spindle cells which are connected into dense bands extending in various direc- tions and forming alveoli; hence the name alveolar. The other portion oi the stroma is intercellular and corresponds to that of the round-cell sarcoma. The arrangement of the cells into nests is suggestive of a carcinoma, but the differentiation is not diffi- cult and depends upon; first, the presence of intercellular sub- stance between the cells which is present in sarcomata but is absent in carcinomata; second, sarcomatous cells are embryonic connective tissue cells and hence contain nuclei relatively large in proportion to the size of the cell, while carcinomatous cells are embryonic epithelial cells and contain nuclei relatively small in proportion to the size of the cell. & OL 805 dee be oeieecoW\ K300 600 d ») 79 8\a B10 © bg D SOLO eM 309 0% fig. 151.—Section of Alveolar Sarcoma from ovary of heifer showing alveoli filled with sarcomatous cells. These tumors grow slowly. They are usually encapsulated and have no tendency to form metastases. They are very mildly malignant. Endothelioma is a tumor composed of endothelium. This is a tumor that is not specifically a sarcoma, but may be so classed. Endothelium has the same origin as connective tissue, 1. e., the TUMORS. 313 inesoderm. Embryonic endothelial cells are structurally iden- tical with embryonic connective tissue cells. These tumors are not very common in domestic animals. An endothelioma was observed in the lung of a dog, another in the testicle of a bull. These tumors may have their origin from the endothelium lining blood or lymph channels, peritoneum, pleura, pericardium, arach- noid membrane, any organs developed from mesothelium, or deflections from any of them. They are variable in shape, size, color and consistency. Microscopically they are composed of cells that most fre< Fig. 152,—Section of Endothelioma from a bull's testicle. Note the bands of connective tissue and arrangement of cells. quently resemble sarcoma cells, although they may approximate the structure of carcinoma cells. The cells may be arranged in tubules, transverse or oblique sections appearing as sections of gland tubules or acini. If arranged in columns transverse or oblique sections appear as cell nests. The cells are usually cubical or spherical in shape, although they may be spindle or even squamous. The stroma varies according to the tissue in- vaded and may be dense fibrous or mucoid. Blood vessels are usually quite numerous, and if the endothelium is derived from 314 VETERINARY PATHOLOGY. the endothelium of a vessel, the vessel may be very irregular in calibre and structure. If the cells occur in columns or nests it will be necessary to differentiate them from carcinomata. This differ- entiation involves the comparison of cells derived from mesoderm and those derived from entoderm or ectoderm. The only essential difference, and that is not constant, is the size of the nucleus. The differentiation may also be governed to some extent by the distribu- tion of the blood vessels. If the cells occur in tubules, their differ- entiation from the adenoma will be necessary. Adenomata may be Fig. 153.—From drawing of a Nodule of a Mediastinal endothelioma. 1. Column of endothelial cells. 2. Diffuse mass of endothelial cells, differentiated by observing the same factors that are used in differ- entiating endotheliomata from carcinomata. Alveolar sarcomata are very difficult to differentiate from endotheliomata, in fact it is some- times impossible, and they may be considered in one class or group. These tumors are not encapsulated and usually form metastases. They usually occur in internal organs and hence surgical relief is impossible. Fatal termination is the usual outcome. Psammo-Sarcoma.—The existence of this type of tumor is questioned by some authorities. They are composed of sarcomatous tissue and have calcified masses or cells within. They are rather TUMORS. Sy 05) rare One case was observed by Harvey, an army veterinarian, and another case was reported as a cholesteatoma in the Journal of Comparative Pathology and Therapeutics These tumors occur most frequently in relation to the brain and particularly the lateral ventricles, in which they are intimately associated with the choroid plexus. Because of their location they invariably produce symp- toms evidencing brain disturbances. Microscopically modified sarcoma or endothelioma cells vari- ously arranged constitute the minute structure of psammo-sarcoma. There is usually evidence of calcification of small centers and there may be cholesterin crystals present Fibrosarcoma.—This is a tumor composed of both adult and embryonic connective tissue. They are quite common, espe- cially in the eyelids and in labial commissures of horses and Fig. 154.—Photograph showing location of tumor in ventricle, Cerebrum. Left lateral ventricle. Cerebellum, Medulla. Psammoma, Ole 09 LO et 316 VETERINARY PATHOLOGY. mules. Several cases of dense tissue growths in the withers of horses have been observed. These animals when presented ap- peared to be affected with chronic inflammation of the subcutan- eous tissue or deeper structures. Most of the above cases were clinically diagnosed as fistulous withers and an operation recom- mended. The operation usually consisted of dissecting away the dense masses of tissue. The cases were usually returned in showing nature of connective tissue, leucocytes, neo- deposits and one blood vessel surrounded by hyaline like substance. Fig. 155.—Photomicrograph plasm cells, lime Fig. 156.—Higher magnification of No. 2. from four to six weeks after the operation with growths larger than those present before the operation. The operation was usually repeated two or three times with the same results. On microscopic examination these growths were found to be fibrosarcomata, being composed principally of fibrous connective TUMORS. SY tissue in which there were some spindle cells and occasionally a few round cells. The presence of both fibrous and sarcomatous tissue is the principal characteristic of these tumors. The num- ber, size and distribution of blood vessels are very irregular. These tumors are not distinctly encapsulated, but they do not form metastases. They are prone to recur after ablation. They may destroy life after a considerable time, as their growth is Fig. 157.—A so called grape sarcoma from uterus of a cow. 318 VETERINARY PATHOLOGY. relatively slow. Operation usually stimulates them to grow more rapidly. Melanosarcoma.—A melanosarcoma is any variety of sarcoma in which melanin is deposited in the tumor cells. These tumors are quite prevalent. Gray horses seem to have a special predis- position to them, but they are also found in bay and black horses, black or red cattle, black hogs, and, in fact, all varieties of do- Fig. 158.—Melano Sarcoma of hog skin. mestic animals regardless of color. On microscopic examination, melanin is found deposited in the tumor cells. The melanin may be in masses or granular and occasionally it may be found out- side of the cells. Excepting the deposit of melanin, these tumors have the same microscopical appearance as the round or sptidle- cell sarcomata described before. TUMORS. 319 Melanotic sarcomata are frequently malignant. In an autopsy of a gray mare metastases of melanosarcomata were found in the liver, lung, spleen and kidney, the primary growth being located in the subcutaneous tissue on the right superior portion of the anus. Another case was observed in which there was general- ized melanosarcomatosis in a short-horn cow. Myxosarcoma.— [his is a tumor composed of myxomatous and sarcomatous tissue. The existence of this group of tumors Fig. 159.—Section of Melano Sarcoma of a horse's liver, showing the deposit of melanin in the tumor cells. is doubted by some pathologists because sarcomata are prone to underge mucoid degeneration, and, because if the mucoid degen- eration is of limited extent and generalized throughout the en- tire tumor, differentiation would be practically impossible. If the mucoid degeneration affects localized areas the differentia- tion is not difficult. One myxosarcoma has been studied. It in- volved the right lobe of the liver of a cow but was not the cause of death. The tumor, about the size of a goose egg, was encap- sulated, soft and pale pink in color. Microscopically it was composed of stellate cells, the pro- cesses of which were apparently united, thus forming alveoli. 320 VETERINARY PATHOLOGY. There were also round cells, some areas being composed almost entirely of round celis and others of stellate cells. The round cells were like the round cells found in sarcomata. The alveoli formed by the stellate ceils were filled with a stringy mucus ma- terial. A few blood vessels were observed but they were not as numerous as in pure sarcomata. These tumors may be malignant. When they occur upon or near available surfaces they usually become necrotic, slough and produce no further trouble. l i) Fig. 160.—Section of a Myxo-Sarecoma, from a cow's liver, showing: . Spaces formed by the union of the processes of the stellate Cells. 2. Sarcoma cells. Chondrosarcoma and tumors composed of chondromatous and sarcomatous tissues are not common. They usually occur in the location most favorable for chondromata. A chicken affected with a chondrosarcoma of the sternum was obtained at a butch- er’s stall at the city market in Kansas City. Microscopically, these tumors are found to be composed of a mixture of chondromatous and sarcomatous tissues in varying proportions. Sometimes the chondromatous tissue is apparently stroma for the sarcoma tissue proper. In other cases the stroma is apparently formed of sarcomatous tissue and the chondro- matous tissue is the essential portion of the tumor. TUMORS. 321 These tumors may grow to an enormous size. They are not as malignant as pure sarcomata and metastatic tumors are rare. They should be differentiated from chondrofying sarcomata and from sarcomata involving cartilage. Osteosarcoma.—This variety of tumors is composed of osseous and sarcomatous tissues. They are rather commen, occurring in the horse, dog and ox. Microscopically, osteomatous and sarcomatous tissues are arranged in various proportions and in various relations, but the combining tissue in any case must be new growth tissue. Ossifying sarcomata are not osteosarcomata, neither are sarco- inata of osseous tissue osteosarcomata. These tumors are usually malignant, but they do not form metastases. Hemangiosarcoma.— These tumors are composed of heman- giomatous and sarcomatous tissues. They are relatively com- mon, occurring in the location common for haemangiomata and may affect any of the domestic animals. These tumors are essen- tially very vascular and are highly colored. In microscopic examination variations are observed in differ- ent hemangiosarcomata. The sarcomatous tissue in some cases appear to have had its origin from the tunica adventitia of the vessel wall; in other cases the sarcomatous tissue appears to have had its origin independent of the vessels. Again, the ves- sels may act as the supporting stroma for the sarcomatous tissue. The vessels may be capillary or cavernous, sinusoid or plexiform. The vessel wall may be practically normal, but more frequently it is either hypertrophied, as a result of increased number of the cellular elements or increase in the size of the cells, or it may be thin, scale-like and atrophied. Sometimes the endothe- lial cells lining the vessels are cubic or columnar in shape, thus diminishing he lumen of the vessel. The sarcomatous cells may be either spindle-shaped or round. These tumors are quite malignant, and they usually grow rapidly. The metastatic tumors are most frequently pure sarco- mata. PABEE LEONA (Wart.) Papillomata are fibro-epithelial tumors. These are perhaps the most common of all tumors. They occur upon the surface of the skin, and upon mucous, serous, and synovial membranes. They are very common upon the skin of calves, especially around the eyes, ears and poll. They occur most frequently on the lips, 322 VETERINARY PATHOLOGY. buccal mucous membrane, and arms of dogs. The skin of the legs and lips are the commen locations in the horse. The lumen of the oesophagus of the ox may be almost occluded by the pres- sence of masses of papillomata. In a horse used for dissecting the cardio-pyloric junction was found to be a mass of these tumors. The mucous membrane of the bladder of the ox, sheep 2} Fig. 161.—From photograph showing Papillomatosis of mucous membrane of lips of a horse, and hog is sometimes studded with papillomata. These tumors have also been observed upon the combs and wattles of fowls. They sometimes occur in horses’ feet but are usually necrotic and do not have the appearance of papillomata. These tumors may be hard, i. e., covered over by stratified squamous epithelium that has become cornified. This variety is TUMORS. 323 invariably found upon the skin and constitutes the growths ordi- narily known as warts. They may also be soft, and are then found upon mucous, serous or synovial membranes, in which case the covering epithelium is not cornified. Hard papillomata or warts may appear as tabulated masses, as fungoid growths or as a mass of villi. Any of the above forms may have a smooth surface or be fissured with a very irregular surface. They vary in size from a millet seed to an apple. They may be single but are more frequently multiple. Microscopically, they are composed of adult epithelium and of fibrous connective tissue in varying proportions. They sug- gest the structure of cutaneous papillae. In fact, they have been es) U2 "Zo Pan 8 ere 55} "/ nes ee “ Hone Cy y ote iia Baler ars s Y, re ale a @| oe i ae cy A Hgeo 60 9 oo s0hddes fp? i BE Al {7 C00 ge aa . ay! ane 2. Paik \ Nee 26 8- rt toe eS eae pa ates j Fig. 162.—Section of Papnilloma from Oesophagus of cow, showing bands of stroma covered by epithelium, described as hypertrophied papillae. The fibrous tissue is the supporting structure or framework of the tumor and contains the blood vessels and nerves when they are present. The epi- thelium is the covering mantle of the fibrous tissue. In the hard papillomata the epithelium is stratified and the surface cells are cornified. In soft papillomata the epithelium may be single or stratified but the surface cells are not cornified. The proportion of fibrous tissue and epithelium in papillomata may be the ‘same 324 VETERINARY PATHOLOGY. as in normal papillae or the fibrous tissue or the epithelial tissue may be in excess. Hence some papillomata are apparently sub- epithelial fibromata and others are masses of epithelial cells upon a very limited fibrous matrix. Papillomata have the same relation to underlying structures that normal papillae have. The stroma of the papillomata has a definite connection with the dermis in cutaneous papillomata and the epithelium apparently originates from the lower layers of the epidermis. Transverse sections appear as areas of stroma surrounded by epithelial cells, while epitheliomata are composed of columns of cells surrounded by a stroma. These tumors are essentially benign. They may result fatally because of mechanical interference, as in the occlusion of the oesophagus or the urethra. They may undergo necrosis, thus providing an entrance for infection and result in fatal septicemia. Papillomata do not form metastases, but they are frequently multiple. Cases have been recorded where the condition papil- lomatosis has been transmitted from one animal to another. By constant irritation some epithelial cells may become enlarged in the subsurface, thus providing a centre from which an epithe- lioma may develop. They respond to medicinal treatment and surgical interference. EMBRYONIC ERITRELIAL TUMORS: This is a group of tumors composed of embryonic epithelial cells, and for description may be divided into three varieties,— (1) carcinoma, (2) epithelioma, and (3) adenoma. Carcinoma is an epithelial tumor characterized by the group- ing of cells into nests or alveoli. They are of rather common occurrence but not as common as sarcomata. Horses and mules, cattle, sheep, hogs and dogs have been observed affected with carcinomata. These tumors have no selective action for any tissue. They have been found affecting mucous membranes, glandular structures, invading muscles and even in bone. They are usually diffuse, although they may be limited by a membrane resulting from reaction of the surrounding tissue. They are usually soft (encephaloid), but they may be quite hard (scir- rhous), depending upon the amount of stroma or fibrous tissue contained. The color of a cut section of a carcinoma is usually gray, dirty-white or pale pink. They may be mottled because of degenerating or necrotic centers or hemorrhage. Lobules may be observed, especially in those carcinomata formed by the cel- lular infiltration into dense areolar tissue. Small blood vessels may be present, but the blood supply is usually very limited and the vessels occur only in the stroma, TUMORS. 325 Microscopically, these tumors are found to consist of embry- onic epithelial cells arranged in nests, the cells having no inter- cellular substance between them. ‘The cells are variable in size and in shape, they may be squamous, spherical or columnar. The uucleus is usually much smaller in proportion to the size of the cell than the nucleus of sarcoma cells. The stroma is usually =n Neg #9: ed eS Fig. 163.—Encephaloid Carcinoma. fye ball, horse. appropriated from the pre-existing tissue and therefore is vari- able in quantity and structure. In some cases sarcomatous tissue constitutes the stroma. The stroma forms alveoli in which the carcinoma cells occur. In fact, the alveoli are, in many instances, simply dilated lymphatic spaces which have been invaded by carcinoma cells. Lymph is usually quite abundant and bathes the nests of the carcinoma cells in the alveoli. Because of the freedom of anastomosis of lymph spaces and the constant flow of lymph, carcinoma cells are easily and rapidly diffused. Karyo- kinetic figures are of common occurrence in rapidly growing carcinomata. There is usually an inflammatory reaction accom- 326 VETERINARY PATHOLOGY panied by a leucocytic infiltration in the adjacent tissue. In rap- idly growing carcinomata the cells frequently completely ob- struct the flow of lymph through the alveoli, resulting in degen- eration or necrosis. Mucoid degeneration is perhaps the most frequent variety, thus producing a mucous mass. Clinically, these tumors are malign. They are not circum- scribed, hence their extirpation is practically impossible. In fact, surgical interference usually stimulates them to more rapid de- velopment, and, in addition, opens an avenue for infection. They A Wii gpl ap Wy ey) ce Vf ANS Uy , Li | / Jt | % Fib. 164.—Section of an Enithelioma of the hock of a horse: was the sequel of an injury. Note the ingrowth of the columns of epithelial cells. form metastases. The metastatic tumors usually occur in the first lymphatic gland that the lymph passes through from the area affected with the carcinoma. Then by metastasis they will be extended on to the next group of elands and finally reach the blood stream and form carcinomatous emboli in the lungs, liver, etc. These tumors should be differentiated from alveolar sarco- mata, endotheliomata and papillomata. The sarcoma cell has a much larger nucleus in proportion to the size of the cell and the cells are usually smaller than carcinoma cells. In a cross-section of a TUMORS. 327 papilla from a papilloma the cells will be found arranged around the stroma instead of in nests as in carcinoma. Carcinomata are sometimes associated with other tumors as fibromata and chondromata, but they are more frequently in combination with sarcomata, in which the sarcomatous tissue forms the stroma of the carcinoma. The sarcoma cells are usually of the spindle-celled variety. Epithelioma.—This type is the result of an ingrowth of epi- thelium into the underlying structures and has been classed by some as a sub-variety of carcinomata. In this variety of tumors Areal vee Rid x? See Ss Sg pees 2 SO = a eos = Fig. 165.—Enithelioma from eye of an ox. there is considerable evidence that they are secondary to surface injuries. A horse with a large fungoid growth beneath the left eye was sent to a Kansas City veterinarian for treatment. The history of the case brought out the fact that the tumor was the sequel of a wire cut. Two similar cases of epitheliomata oc- curred in the eye of two cows after severe attacks of keratitis. Epitheliomata are not rare and may affect any of the domestic animals. They always occur primarily in relation to epithelial surfaces. The surface is usually denuded and there is usually an acrid, fetid discharge. They may appear as elevated nodular 328 VETERINARY PATHOLOGY. masses or as ulcerated surfaces and are rarely encapsulated. Their consistency varies with the amount of connective tissue stroma present. Their color is uszally white or gray, although it may be quite variable as a result of degeneration or necrosis. The quantity of blood depends upon the vascularity of the tissue invaded. Microscopic sections of epitheliomata are usually very similar to carcinomatous sections, indeed, it is sometimes impossible to differentiate them from carcinomata. In the beginning of the tumor formation, if sections are made ee to the sur- a SEL Wg) yy Se ay a Fig. 166.—Section of a pearl cell Epithelioma of the Subeutum of a 14-year-old dog, showing pearl cells and columns of epithelial cells. face, the ingrowing epithelium will be observed as columns of cells. These cell columns extend into the areolar lymph spaces and are then distributed the same as in carcinomata, the pre- existing tissue stroma becoming the stroma of the tumor. The presence of the epithelial cells or their katabolic products some- times produces a chronic inflammation of the stroma. The pres- sure produced from the thickened stroma upon the columns of epithelial cells may result in the formation of “pearls.” Epithe- liomata containing the “pearls” are designated pearl-cell epithe: liomata. TUMORS. 329 Clinically these tumors are not as malignant as carcinomata proper, and they have less tendency to form metastases. They are frequently completely destroyed by surgical interference. Adenoma.—This is a glandular tumor. While it is similar toa gland it is functionless or has a perverted function. Though occurring more frequently in glands, as the kidney, mammae, mu- cous or sebaceous glands, testicle, liver, etc., they may occur in any tissue. Swine and dogs are most frequently affected with them. ‘They are usually circumscribed, rather firm, nodular, white or grayish-white masses, varying in size from a pea to a Fig, 167.—Photograph showing Mammary Adenoma of a bitch. man’s head. In section the gross specimen usually appears lobu- lated, and, if the tumor is large, there are usually necrotic centres here and there through it. The blood supply is limited, the ves- sels usually being obstructed by the pressure of the new-formed adenomatous tissue. In microscopic sections glandular cells are found in various arrangements as tubules, acini, etc. The mimicry, however, is not complete, and there is usually little difficulty in differentiat- ing adenomata from normal gland tissue. The cells vary in shape from short cubical to tall columnar. They are usually 330 VETERINARY PATHOLOGY. arranged in a single layer, although the tubules or acini may be entirely filled with cells arranged layer upon layer. The type of cells adheres to the description given in discussing carcinoma. The stroma is usually composed of fibrous connective tissue and is variable in amount. Blood vessels are found within the stroma. The cells lining the acini may be active and the secre- tion is frequently retained, thus resulting in a cyst-adenoma. The accumulated secretion may cause degeneration of the stroma, and the acini rupturing one into another produce a large cyst. CR (etka > WS gs LIEN SAS Sg ss3 ase * . 2s 3 = SR ee Ne * oe GH Ye Ze, f re: 0 7 Bourne \% Fig. 168.—Section of an Adenoma from the frontal sinus of a mule, showing the arrangement of tumor tissue into acini and tubules, Clinically these tumors, as a class, are malignant, but do not produce fatal results as rapidly as carcinomata. Many individual adenomata are benign. A horse’s tail was amputated that for three years had been affected with an adenoma of the sebaceous glands. These tumors rarely recur when removed. From experience it has been found that mammary adenomata of the bitch frequently result fatally immediately after operation. (The operation appears to produce sufficient shock to destroy life.) Adenomata are extended TUMORS. Soll by means of the lymph. Various combinations of adenomata are common. Adeno-Sarcoma.— This is a tumor composed of adenomatous and sarcomatous tissue. These tumors are seldom observed dur- ing life because they cccur in the kidney, and it is not an easy matter to palpate the kidney in the domestic animal unless there is extreme emaciation. They usually affect only one kidney. They occur in young animals and are most common in the hog although one has been observed in a horse. These tumors grow rapidly and may become very large. Day reported one that weighed 27.2 kilograms (60 Ibs.) found in the kidney of a hog. Renal adenosarcomata usually have their origin near the kid- ney pelvis. The renal tissue is gradually displaced by the tumor, and in some instances the kidney tissue is entirely destroyed as a result of pressure atrophy. The tumors are usually confined to the kidney, but they form metastases, in the lung (through the blood), or in the sublumbar lymph nodes (through the lymph.) In gross appearance, these tumors are irregular in outline. They are usually surrounded hy a thin fibrous capsule from which fibrous bands project into the tumor dividing it into ZEON WS Te 899 28S Feet aehoe ae ot$03.725 Er) Cis Ss 99 2oB9 0 A oe 0 D”,”, PP RESP ad ‘0, rea EN es nese SSF oo 8. fone 16) Og, So 07 OGY 23 $3 % oe o8'd Go detele tos Le, Fig 169.—Section of an Adeno-Sarecoma of the kidney of a hog, showing the sarcomatous tissue between the acini and tubules. SoZ VETERINARY PATHOLOGY. irregular jobes. These tumors are usually mottled, though they may be uniform and of a white or light gray color. Microscopically, adenosarcomata are composed of epithelium and connective tissue. The amount and arrangement of the two types of tissue are variable. Some areas may be entirely epi- thelium (adenomatous) and other areas connective tissue (sar- camatous). The epithelium is arranged as glandular tissue, the tubes and acini of which are irregular in shape and size and may contain disintegrating, epithelial cells or their products. The epithelium is usually arranged in a single layer in the tubes and acini though they may be grouped in some instances and Fig. 170. —Section of a Cystadenoma of the mammary gland of a sheep, showing: 1. Coagulated cystic contents surrounded by an atrophied acinous wall. thus appear similar to carcinomatous nests of cells. The epithe- lial cells are small and usually contain finely granular chromatin. The connective tissue cells are usually fusiform although they may be nearly spherical in shape. They contain relatively large nuclei in which granules may be observed. Cystadenoma is also common, especially in those adenomata that produce secretion. They are found in the adenomata of the mammary and sebaceous glands. Hypernephroma are tumors which may be classed either with ‘PU MORS. 333 sarcomas or carcinomas and is composed of tissue similar to adrenal tissue. They occur most frequently in the kidney, ovary or ad- renal body itself. Fingle reported case a hypernephroma in a 23 years old mare. Bloody urine was the first evidence of disease in Fingle’s case. On autopsy a renal tumor about one foot in diameter was observed. Hypernephromas are rarely diagnosed as such in living domestic animals. They are variable in size, fre- quently weighing as much as five kilograms (11 lbs.) Usually gray im color and invariably containing hemorrhagic areas they thus appear mottled. There is usually an encapsulating mem- brane present. Blood-vessels are numerous, especially in the stroma. Degeneration and necrosis is of common occurrence. X 250 Fig. 171.—Hypernephroma of the kidney of an ox, showing large typical hyperne- phromatous cells containing fat droplets. Microscopically, these tumors are found to be made up of large cells similar to epithelial cells and usually containing fat droplets. These cells are arranged in rows or columns, the columns being separated from each other by a small amount of stroma. The columns of cells may be quite variable in their diameter, appearing at times as long, slender columns and again as rather long nests of cells. The stroma is composed of fibrous connective tissue and contains many blood-vessels. : Clinically, these tumors are very malignant, and, although 334 VETERINARY PATHOLOGY. they are encapsulated, they form metastases through the blood. They frequently result fatally in the human, even after operation, probably because of the liberation of considerable of the adrena- lin substance which increases blood pressure to mich an extent that heart failure supervenes. PEACE N TOMA: (Syncytioma.) A placentoma is a tumor composed of tissue similar to the chorionic villi. These tumors have been described under a variety of names as syncytioma malignum, deciduoma malignum, chorio-epithel- ioma, epithelioma seritonale, chorio-carcinoma. Only recently have placentomata been recognized as distinct tumors. A placentoma is essentially a tumor of the uterus. They are not common in domestic animals but this may be because of fail- ure to recognize them. The uterus or fallopian tube is their most frequent location. They occur more frequently after spur- ious or mole-pregnancy and usually appear a short time after parturition. Abortion is a predisposing cause. The primary tumor almost invariably occurs in the uterus though a few cases have been reported in women in which the primary tumor was in the kidney. They are very malignant. These tumors appear as soft, spongy, villous, bleeding masses and are variable in size. They have the general appearance of placenta or foetal membranes in both the primary and the metas- tatic tumors. They begin to develop at the cotyledons or zone of placental attachment and rapidly extend into the uterine mus- cular tissue and invade blood vessels, thus metastases occur in a short time after the tumor appears. Because of their struct- ure (embryonic cells and rich vascular supply) they grow rap- idly. The presence of a placentoma is indicated by uterine hem- orrhage occurring a few days after normal parturition or abor- tion. The uterus is enlarged and the affected individual rapidly becomes anemic and emaciated. The uterine discharge usually contains shreds of the tumor and the cavity of the uterus is occupied with a soft bleeding mass. ' Microscopically, these tumors are composed of a protoplasmic ground-substance, which is arranged in an irregular network forming alveoli. The protoplasmic mass is usually continuous, there being no evidence of cell partitions, and it contains many nuclei thus forming a syncytium. Within the alveoli of the pro- TUMORS. 335 toplasmic mass occur many small variously shaped cells. Blood cavities and canals are abundant and hemorrhagic areas are not uncommon. TERATOMA. These tumors are composed of the different kinds of tissues that approximate the structure and arrangement of normal tissue so closely that it is difficult in some instances to differentiate them macroscopically or microscopically from normal tissues and organs. Teratomas are also so closely related pathologically to malfor- mations, that in some cases it is impossible to determine which condition exists. Structurally they are found to be composed of either embryonic or adult tissues. Cutaneous structures are the most frequent tissues observed in this class of tumors, although tissues of bone, muscle, intestine, rudimentary eyes, brain, etc., have been found in them as well as sarcomatous and carcinomatous tissue. Fig. 172 and Fig. 173.—Dermoid Cysts, natural size. These tumors are quite variable in size, shape and color. In consistency, they vary froma viscid mass to dentine and enamel. They are usually single, grow slowly and rarely form metasta- ses, although a few have been observed that grew rapidly, metas- tasized and recurred when removed. They frequently undergo degeneration tending to cystic formation. Clinically, teratomata are benign, only rarely terminating fatally. ; 336 VETERINARY PATHOLOGY. Etiologically, they are as mysterious as the other types of tumors. They may have their origin from tissue inclusions. Some teratomata may succeed imperfect tissue union. The theory of Fig. 174.—Dermoid Cyst from eye of a steer, showing tuft of hair, growing upon cornea. parthenogenesis may be applicable in the explanation of some of them, but the specific cause or causes of teratoma- ta has not yet been determined. Teratomata are of frequent occurrence in all domestic ani- mals but are more prevalent in equines. They are found in any tissue and in all parts of the body although they are more frequent in the skin, ovaries, testi- cles, kidneys and parotid glands. Be- cause of the hetero- genous structure of teratomasa they are difficult to classify. Dermoid cyst are ter a fom ata com= posed primarily of skin and its appen- dages (hair, sebace- ous. glands, horns, teeth, etc.) These cysts are due to the dislocation of epithelium during development. The most common location is in the connective tissue of the head and neck. They may be solid, but are more frequently cystic. In size they vary from a pea to a basket ball. There is usually sur- rounding them a dense capsule from which a villous mass may be TUMORS. $37, observed projecting into the cyst cavity. Extending from the vil- lous projection are tufts of hair or teeth. The villous is, in struc- ture, very similar to skin. In some teratomasa hair and teeth are produced directly from the inner portion of the cyst wall. Cys- tic dermoids usually contain hair and a pultaceous matevial de- rived from the sebaceous glands or they contain teeth and a vis- cid fluid. Dermoid cysts without any capsule are occasionally observed. The accompanying cut illustrates hair extending from the anterior surface of the eye. Those found in the ovaries ao > * ” ‘om > ar ry @ vy L cst sa ,, } & —« ¥ Boe ~ ae me “we tan ach eo Cru Came te SOT OTE Ze: ee « Se ebb e ptete CF wa hobat*s Wig OMe he Fig. 175. —Dentigerous Cyst on left inferior maxillary of 8 yéars old@ colt containing 431 teeth. Removed Dec. 11, 1905, by H. M. Stevenson, Perry, Iowa. usually contain elements of all three germ layers. Those of the testicles may contain vestiges of all the germ layers, but are usually cystadenomatous or cystocarcinomatous in type although they may contain cartilage, teeth, osseous tissue, etc. Solid der- moid cysts are a heterologous mass, of embryonic or adult tissue. Dentigerous cyst is the name applied to those dermoid cysts containing teeth. These are the most important to the veterin- arian because they are of the most frequent occurrence. They are invariably encapsulated and may or may not ccatain a villus 338 VETERINARY PATHOLOGY. projection. The teeth vary from an irregular conglomerated mass of dental tissue to those perfect in form and structure. The con- stant production and accumulation of the containing viscid fluid results in enlargement of the cyst and frequently rupture of the capsule and the production of a fistula. The most frequent lo- cation of dentigerous cysts is near the base of the ear in the region of the parotid gland although they may occur in any other place especially in the ovary and testicle. They are most common in horses. Cholesteatoma is a teratoma composed of pearl like masses of endothelium in which there is more or less cholesterin. They are not common but have been observed in the brain, (choroid plexus and tuber cinereum) and urinary organs. CYSES: DEFINITION. ETRMOLOGV: Retained secretion. Obstructed outhow. Excessive production in ductless glands. Retention of hemorrhagic extravasate, Colliquation necrosis. False bursae. Parasites. SEI Ee OHO TOM Gale VARIETIES. Retention; Atheroma. Exudation; Hygroma, Shoe boil, Capped hock, Meningocele. Extravasation; Hematocele, Hematoma. Deaeneration; Colliquation necrosis, Hydatiform Parasitic; E chinoccosis, Measley pork. Dermoid; Cutaneous, Dentigerous SECONDARY CHANGES. [HU HACIRS. A cyst is a bladder like growth surrounded by a capsule and containing a liquid, semiliquid or gelatinous material. Cysts are not true tumors. However, a tumor may become cystic, (Cystoma,) and the capsule surrounding a cyst may proliferate and become a true tumor. Collections of inflammatory and oede- matous fluids, are not usually considered as cysts. Cysts may be single or multiple. The latter are designated multilocular cysts. Cause.—Cysts may be caused by, 1. obstruction of gland ducts, thus favoring accumulation and retention of a normal secretion TUMORS. 339 or excretion, e. g., renal cysts; 2. By excessive secretion into duct- less structures, e. g., distension of bursae; 3. By extravasation into the tunica vaginalis sac, e. g., hematocele; 4. Liquefying necrosis, e. g., formulation of cysts in the cerebrum of horses affected with “blind staggers.” 5. Parasites, e. g., Cysticercus cellulosae. Structure.—The cystic wall varies according to the age cf the cyst. In the beginning it may represent the original gland structure or a condensation of the normal tissue of the part. Later the cystic walls may be lined with epithelium or endothel- ium, which actively secretes as long as the cyst grows. The cys- tic capsule may be composed entirely of fibrous connective tissue. In some instances the primary capsule is fibrous and later an endothelial lining develops. The cyst wall or capsule may be firmly adherent to the adjacent tissue or it may be loosely at- tached. Fig. 176.—Cyst on Abdomen of Mule. (Courtesy of American Veterinary Review) 340 VETERINARY PATHOLOGY. The cystic contents varies according to the nature of the cyst. Urine, milk, saliva, mucus, semen, liquor folliculi and other secre- tions and excretions are represented in cystic contents. Blood i. e., hemorrhagic extravasates and various tissues that have undergone colliquation necrosis may represent the contents of cysts. The various secretions, excretions, extravasates, exudates and necrotic tissue usually undergo some modification when re- tained within a cyst. Varieties.—Fetention cysts, those resulting from the accumu- Fig. 177.—Uterine Cyst the capsule of which had become osseous, lation and retention of normal secretions, e. g., renal cysts, mam- mary cysts, testicular cysts, ranulae, mucus cysts, sebaceous cysts ( Atheromata ). Of 3,000 kidneys from swine 108 were found to be cystic. An ovarian cyst in the ovary of a goat was reported by Hebrant & Antonie. The ovary in this case was about the size of a three gallon pail. Exudation cysts, those resulting from excessive secretion into ductless glands or cavities, e. g., ovarian cysts, hygroma, capped hock, meningoccie. Ewtravasation cysis, those resulting from hemorrhage into tis- sues or closed body cavities, e. g., hematocele, hematoma. Degeneration cysts, those resulting from liquefaction of ne- crotic tissue ,e. g. colliquation cerebral cysts. Parasitic cysts, those resulting from the development of para- sites in the tissue, e. g., cysticercus cellulosae, cvsticercus bovis, cysticercus echinococcus, etc. TUMORS. 341 Dermoid cysts, those resulting from inclusion of cutaneous tis- sue. These have been discussed under the head of teratomasa. Implantation cysts, those resulting from transplantation of epi- dermal cells into the sub-epithelia) connective tissue. When such transplanted cells continue to multiply and form a continuous epi- thelial mass the central part of which sooner or later undergoes necrosis and become of a semisolid consistency, thus forming a pultaceous mass. Secondary Changes.—The cystic wall may become the seat of inflammatory disturbances, neoplastic formation or necrosis. In some instances cysts are destroyed because of the disintegration of their capsule, by disease. The cystic contents may undergo degeneration, become in- spissated or calcified. Effects—The effects of cyst formation depend upon the tissue involved and the size and nature of the cyst. The cysts frequently become so large that the entire organ is destroyed, e. g., ovarian and renal cysts. In some cases the cysts may destroy life, especially if a vital organ, e. g., the brain is in- volved. Cysts may persist for years and be of no serious con- sequence, on the other hand they may seriously inconvenience the functional activity of the part involved and impair the health of the animal from the beginning. CHAPTER XS: FEVER (Pyrexia). DEFINITION. ETIOLOGY.—Tovwins; ptomains; katabolic tissue products; drugs. PERIODS OR STAGES (Course). Onset (Stadium Incrementi). Acme (Stadium Fastigium). Decline (Stadium Decrementi). Convalescence. VARIETIES, according to Course. Regular. Irregular, Duration and temperature variation. Ephemeral. Continuous. Remittent. Intermittent. Severity. Sthenic. Asthenic. SYMPTOMS. Chill, diminished secretious, increased heart aciion and respircticn, nervousness and restlessness. LESIONS. Parenchymatous degeneration, hemolysis, hyaline degeneration, loss of fat. Body heat is a product of metabolism. The body heat or temperature of warm blooded animals is practically constant, although changed environment, diet and use or occupation pro- duce some variations. Thus a horse confined in a barn has a temperature .5 to 1° F. higher than when not so confined, pro- vided the diet is the same in both conditions. A narrow ration is conducive to increased oxidation and consequently a higher temperature. Animals in action have a higher temperature than when at rest. Thus a dog’s temperature is from 1 to ° F. higher immediately after than it is before a chase. The accurate regulation of body temperature is accomplished by the action of the thermo-regulating center or centers. Tissue action is always accompanied by increased heat production, and frequently different parts of the same animal may vary 1 to 6° F. in temperature. The equalization of body heat and the distribu- tion of heat to the different parts of the body is accomplished by means of the circulating blood. Heat is continually produced in the animal body and is constantly eliminated from the body 342 FEVER. 343 in the excretions (air, perspiration, urine and feces), as well as by direct radiation. The relative amount of heat dissipation by the excrementation and by radiation varies in different animals. Normal temperature is the balance of equilibrium maintained between thermogenesis (generation of heat) and thermolysis (dissipation of heat). The normal temperature of an animal used during the day is about 1° F. higher in the evening than in the morning. Fever is a condition in which the equilibrium between ther- mogenesis and thermolysis has been overthrown, i. e., there is a disturbance of metabolism accompanied by increased tempera- ture. It is not a disease but a symptom complex, common to several different pathologic conditions. Fever should be dif- ferentiated from heat stroke and sunstroke. In heat stroke there is no disturbance of thermogenesis or thermolysis, but the ther- molytic centers are unable to cope with the existing external conditions, and there is accumulation of heat in the body, whereas fever is a result of disturbed equilibrium between thermogene- sis and thermolysis. Sunstroke is a condition produced by the action of actinic or chemic rays of the sun upon the nerve cen- ters, temperature variations being only a predisposing factor. Etiology.—Fever is usually caused by bacterial products as toxins, endotoxins and bacterial proteids. Tissue products as leucomains, peptones and various albumins are also capabie of producing fever. Certain therapeutic agents may be causative factors of fever. Course.—The course of a fever may be divided into four per- iods or stages, as follows: Onset (stadium incrementi) is the period of increase between the time of normal temperature and the time that the tempera- Fig. 178.—Charts showing two fever curves. On the left is given the temperature and on the top each number signifies one day or 24 hours. From 1 to 13 is the onset; from 13 to 17 and 20 respectively the Acme; from 17 to 32 is» | a gradual decline (lysis); and on 20 is shown a rapid declined (crisis). 344. VETERINARY PATHOLOGY. ture reaches its average height. The length of the onset and the temperature during this period is variable. Acme (stadium fastigium) is that period of time that the temperature remains high. It is the time from the termination of the onset to the beginning of the decline. Decline (stadium decrementi) is the time extending from the termination of the acme until the temperature reaches the nor- mal level. A sudden decline, 1. e., when the temperature sud- denly changes from acme to normal, is called crisis. In a large percentage of the cases of fatal equine pneumonia the tempera- ture suddenly drops from the acme to normai, or even subnor- mal, the sudden change (crisis) causing death. Excessive varia- tions, as a sudden rise of temperature of a sudden fall of tem- perature (may be to subnormal) are of rather frequent occur- rence a short time before death and is called the moribund or premortal stage, A gradual decline from acme to normal is called lysis. Convalescence is that period extending from the time that the temperature becomes normal until the animal has recovered. This period varies in length, a long continued fever essentially requiring a long period for convalescence. The temperature variation during this period is inconstant, but usually there is only slight fluctuation from the normal. Varieties.—I*evers may be classified according to course, to duration, and to temperature variation as follows: According to the course fevers are regular and irregular, typi- cal or atypical. A regular fever is characterized by the appear- ance of the various stages or periods of fever as described above. An irregular fever is one in which the stages are not distinct or are not regular in their appearance and duration. According to duration and temperature variations, fever may be ephemeral, continuous, remittent or intermittent. Ephemeral fever is of brief duration, usually lasting not longer than 24 hours. It is the type of fever observed in nervous, ex- citable animals. This variety of fever may be produced at will by some nervous women. Continuous fever is that type in which there is a continuous high temperature. In continuous fever there are usually morn- ing and evening variations the same as in the normal tempera- ture. Croupous pneumonia without complications is an example of disease in which there is a continuous fever. . Remittent fever is characteristic of pyemia and is recognized by the irregularly periodic variations of temperature in which the temperature is always above normal. FEVER. 345 Intermittent fever is the name applied to that type in which there are periodic variations, the temperature becoming normal between the fever periods. Intermittent fever is observed in equine pernicious anemia. Fever may also be classified as: Ist. Sthenic. 2nd. As- thenic. Sthenic fever is active, vigorous and destructive. As- thenic fever has an insidious onset and is slow in action. Le eT CT VT, Te re Se fe a Ve ee 25 26 27 2¢ 29 Bo ar 22 JGGeo anne ae even eae Ese Eee in = Ieee es ea ee oe a | Vs 5] 3) KS CG Wi i WB 104 b = las i eee een eae 3 eS ee | AZ ea et ee eee ete (I Ar Ces eal eee Eve weet Rese eteaae Jn ekg tenses ‘4 Sonne ee as see eee eee ts SS OO Fig. 179.—Continuous fever chart showing morning and evening variations, but a continuous high temperature. Symptoms.—Fever is usually ushered in by a chill because of the constriction of cutaneous vessels which thus diminishes the temperature of the skin and produces the sensation of chill- ing. There are diminished secretions, as perspiration, saliva and urine. In long continued fever there is constipation because of absorption of fluid from the intestines. The pulse rate fs usually Tent ey Oh ie 07 te EO PID D LOA RRS ICR TAS Re SCR SO BSL JOfeGos y 46) e Hens eaves akeclece eae ne EEE EEE Fig. 180.—Remittent fever chart, showing variations in which the temperature is always above normal. increased and its character is changed because of the action of katabolic products on the nerve centers. Respiration is increased probably because of an effort to eliminate large quantities of air and waste material, and thus there is a tendency for the tem- perature to be diminished. The affected animal is more or less nervous and restless. 346 VETERINARY PATHOLOGY. i Semis ERR ERE Aeneas Se Senne Ee Sees aaee EC op AE Fig. 181,—Intermittent fever chart in which there are periods of normal tempera- ture, Lesions.—All parenchymatous — structures are affected with cloudy swelling, the extent of which depends upon the degree of temperature and its duration. Hemolysis is more or less ex- tensive. Chronic or iong continued fever usualiy causes hyaline degeneration, especially of the vessel walls. The affected animal rapidly diminishes in weight because of the consumption of fat. {0s 42 075 2161718. 1G. 2090 9% D3 Ba As 26 97 Ae 9. 30 car SR CHAPTER XII. INFECTIVE GRANULOMATA. Infective granulomata embraces a group of specific inflam- matory conditions characterized by the proliferation of endothe- lial cells, fibroblasts and other cells. Though the consideration of the following diseases belongs more properly to a discussion of infective diseases, their description will be of value to the stu- dent of general pathology. LUBERCULOSIS. Tuberculosis is a specific, infective disease, caused by the bacterium of tuberculosis affecting practically all of the higher animals and also some of the lower forms of animal kind. Extent.—McFarland states that 14% of the deaths in the hu- man family are from tuberculosis. It is probable that 25% of all humans have or have had tuberculosis. The prevalence of animal tuberculosis is variable in different communities, the percentage depending upon methods employed for control and eradication under different sanitary laws, upon transportation rules and regulations and upon the conditions un- der which the animals are maintained. The exact percentage ol tubercular animals in any country is not known, but the relative number has been determined by tuberculin testing and by post- mortem examination at abattoirs. In the United States the percentage, generally speaking, is low in comparison with other countries. According to the post-mortem findings of 7,621,717 cattle slaughtered in United States establishments having official inspection during the fiscal year beginning July Ist, 1906, and ending June 30th, 1907, 29,835, i.e, .4% were tubercular. This percentage is probably below the actual percentage, as dairy cattle are more extensively affected than beef cattle. The Secretary of Agriculture in his report for 1908 holds that 1% of beef cattle and 10% of dairy cattle are tuberculous. According to the above report 2% is the estimated prevalence in the United States of tuberculosis among swine. Porcine tuberculosis is apparently on the increase in the United States. In Germany it varies from 1-7%. Equine tuber- 347 : 348 VETERINARY PATHOLOGY. culosis is not common in the United States, or at least only a few cases have been reported. Tuberculosis is usually found in those horses and mules that have been fed on tubercular cows’ milk. Tuberculosis of goats is rather rare and the disease is still less common in sheep. Dog and cat tuberculosis is not uncommon and is usually observed in pets of tubercular humans, although barn cats, espe- cially those fed milk from tubercular cows, frequently become tubercular. (A dairy was recently inspected in which 68% of the cows were tubercular and on autopsy three barn cats also were found to be affected in a like manner.) Tuberculosis of fowls is more prevalent in the United States Fig. 182.—Bacterium Tuberculosis Bovine. Pus showing leucocytes and bacterium tuberculosis, than is ordinarily suspected, although the percentage of affected birds is difficult of determination because there is at present no official inspection of fowls. Etiology—Tuberculosis is caused by the Bacterium tuberculo- sis. This bacterium has rounded ends and is frequently slightly ent; It varies: trom 2 to. 5 microns in length and ftom! 3,105 in width. (These bacteria may appear as long, delicate, mycelial threads, branching forms, or even as a ray like fungoid growth, the form depending upon the environment. The pleomorphism of this micro-organism has caused some doubt as to its classifica- tion as a bacterium.) The Bacterium tuberculosis may occur singly or in pairs, and it is not uncommon to find several lying INFECTIVE GRANULOMATA. 349 side by side. They do not form spores, but they may contain granules and vacuoles, and they may have a beaded appearance because of fragmentation of their cytoplasm. The Bacterium tuberculosis is extremely resistant to external injurious influences, probably because of a wax-like substance that constitutes about one-third of the body weight and forms the principal part of the external covering or capsule. (These bacteria are stained with difficulty but when once stained retain their stain even though subjected to the action of alcohol and acids.) The staining peculiarities are probably due to a fatty substance they contain. Source of infection—The bacterium tuberculosis may be transmitted direct from tubercular to healthy animals, but infec- tion is more frequently obtained from foodstuffs, or barns, feed racks, watering troughs, posts, soil, ete. Tubercular animals are almost constantly eliminating the bacterium which contam- inates everything that the tubercular discharges contact. The cadavers of tuberculous animals are usually deposited in the soil, and, in many instances, the proper precautions are not taken to destroy the infecting micro-organism. Infected manure is spread upon the soil and thus it becomes infected. The various crops, including hay, grown upon a tubercular infected soil, may be contaminated with the Bacterium tuberculosis and infect sus- ceptible animals that consume such food. Sometimes the car- casses of animals dead of tuberculosis are thrown into rivers or creeks, thus infecting the water. The waste products of many small slaughter houses are fed to hogs and this affords oppor- tunity for them to become infected. Skimmed milk and whey from creameries and cheese factories are also sources of tuber- cular infection. Channel or avenue of entrance of the infection—The Bacter- ium tuberculosis may gain entrance into the tissues of a healthy, susceptible animal through the mucous membranes or through abrasions of the skin, though the latter mode of infection is not of common occurrence in domestic animals. Cutaneous infec- tion is occasionally observed in the mammae of sows and in the castration wounds of barrows. From clinical and experimental evidence and autopsy lesions observed in abattoirs, it seems evident that the digestive tract is the principal channel of entrance of the Bacterium tubercu- losis in hogs, cattle and fowls. It was originally erroneously concluded that the presence of pulmonary tubercular lesions was positive evidence that the infection had gained entrance through the respiratory tract. Tubercular free experimental animals fed 350 VETERINARY PATHOLOGY. foodstuff contaminated with the Bacterium tuberculosis have frequently become affected with primary pulmonary tubercular lesions. (The possibility of inhalation of the infection was care- fully guarded against in these experiments.) It is presumed that the Bacterium tuberculosis is incorporated by leucocytes in the digestive tube and that the leucocytes then pass through the intestinal wall into the lacteals and thence to the thoracic duct to the right heart and on to the lung, the first capillary system encountered, where they may lodge and establish tubercular foci. No doubt the respiratory tract is the channel of entrance in some cases of tuberculosis, but the number of animals infected through this channel is very small. An occasional case of tuberculosis may be the result of infec- tion through the genito-urinary organs. Thus the penis of a bull may become infected by serving a cow afflicted with uterine or vaginal tuberculosis, and this same bull by copulation may infect other cows. Tubercular lesions are occasionally observed in the superficial inguinal glands of steers, and this may be the result of infection in the castration wounds. Conjunctival infection may occur as a result of forcible dis- charge of infection from the respiratory tube of an affected animal, In summarizing, the digestive, respiratory, cutaneous abra- sions, and genito-urinary organs are the principal channels of entrance of the Bacterium tuberculosis, the frequency being in the order mentioned. Lesions.—The characteristic lesion of tuberculosis is the tubercle. A tubercle is a nonvascular nodule, composed of leu- cocytes, endothelial, giant and connective tissue cells, with a tendency for the central part of the nodule to undergo necrosis. The lesion may vary in animals of different genera and in differ- ent animals of the same genus. Thus tubercular lesions in hogs may differ in some particular from those in cattle because of variations in the resistance of the hog and ox. Variations of the tubercular lesions in different individuals of the same genus occur because of variation of individual resistance of the infected ani- mal and variation of the virulency of the infecting organisms. Tubercular lesions may be modified or obscured by lesions re- sulting from secondary infections. The initial or primary lesion may occur in any tissue or organ. Lymphoid tissue. however, is more frequently affected than any other. The Bacterium tuberculosis and its products are the etiologic factors in the formation of a tubercle. The bacterium having lodged in a tissue favorable for its growth and development, be- INFECTIVE GRANULOMATA. 351 gins to multiply and to eliminate those products that stimulate the surrounding connective tissue and endothelial cells to in- crease in number, and, at the same time, exerts a positive chemo- tactic action upon leucocytes. If the influence of the bacterial products is exerted upon the connective tissue and endothelium, the resulting tubercle will be composed of connective tissue cells and endothelial cells, and if the influence of the bacterial pro- ducts is of a chemotactic nature, the tubercle will contain leu- cocytes. Structurally, a young tubercle consists of a cellular focus in- fected with varying numbers of the Bacterium tuberculosis. As Fig. 183.—Small cellular tubercle; liver, x500. Showing small round cells with tu- bercle bacilli scattered here and there, also a few partially destroyed hepatic cells, 352 VETERINARY PATHOLOGY. the bacteria multiply the quantity of their products is increased, and these stimulate cellular multiplication and accumulation, and thus the tubercle grows. The formation of a tubercle constitutes a tissue reaction, but there is no vascularization; that is, no new blood vessels are formed, and the existing capillaries in the invaded tissues are finally obliterated. A tubercle is, therefore, strictly non-vascular, although in the very beginning the affected zone may be hyperemic. Cells constituting a tubercle obtain nutriment from adjacent tissues by absorption. Tubercles grow by multiplication of the peripheral cells, the central cells becom- ing degenerated after they have consumed all available nutrition. The structure and appearance of a tubercle varies according to its age, thus: a tubercle in the very early stages is a cellular mass, a little later the central portion of the cellular mass becomes necrotic, and at about the same time a median zone, consist- ing of bacteria, endothelial, and, in some cases, giant cells, becomes evident; the outer zone is the active zone and is com- posed of bacteria, connective tissue cells and leucocytes. As the tubercle becomes larger the necrotic zone extends to the median and outer zones toward the periphery. Necrosis is usually evident in tubercles that have attained the size of a pea. The central necrosis is primarily of the coagulation type, but the coagulated necrotic tissue may become liquefied, always be- comes caseous and usually calcified according to the quantity of fluid contained. The calcification may be limited in extent, the necrotic tissue containing small calcareous particles that cause the necrotic tissue to have a “gritty feel,’ or it may be so ex- tensive that the tubercle cannot be dissociated except by the use of a sledge. Liquefied tubercular necrotic tissue (pus) is yellow- ish in color in the ox, dirty white in hogs and yellowish in fowls. It is not sticky, although it becomes quite thick and is finally caseated.t. Tubercles may vary in size from a microscopic point to large masses. All tubercles are small in the beginning and are usually entirely cellular. Small cellular tubercles in which there is no necrosis are designated miliary tubercles. Miliary tubercles ap- pear as minute, grayish, translucent, pearl-like specks or nodules. If all the lesions in an affected animal are miliary in character, the disease is termed miliary tuberculosis. Miliary tuberculosis is common in hogs. The appearance of a tubercle changes when central necrosis begins. The color of caseous and calcareous tubercles varies from a dirty white to a yellow color. The tubercles may or may not be encapsulated. The capsule of a tubercular lesion is rela- INFECTIVE GRANULOMATA, 353 tively thin, though it is tough. Secondary tubercles may develop from a primary tubercle, and daughter tubercles may develop from a secondary tubercle, thus are produced the irregular nodu- lar tubercular masses. The tissues contiguous to a tubercle are ischemic, probably because of the enfringement of the affected areas with lymphoid cells. , Little difference is noted in tubercular lesions in the various My TutINy LM, oy Bee LUPE by sacra Ja) eae - pray. BHA INS 3 : SON TM ee geese NW ees Sarees, SA eS eed oar Becec 1088 ca doe coe ve (iz) , Z Boa ROE 4 ; a 3 CIS BOS Se Oc O88 SGEOSSeRES TRIS eT Bia Snn 8 S905, bees | Oe eee a peice Sica Saree | eee Bory On OY oOo pie \Beho ae Peace peng ea ‘Sor gb, 826? Babee 1: sa ‘ De Se ps po SI AN ae Waid rn ay ree B8oees 7 i es C YW, 4 74, wS v 7, Ses Lay ps Ye 7 “4 : Le tor OOo. 39 Op CA ue o ® [) oe (ge eo 6 Bs Be ee ! \ ) eure Vr wae ES) 4 E930 weeelosss Soonauees eet by > >) Oh Re ees oe Fig. 184.-—A Lesion of Tuberculosis from the Post-pharyngeal Lymph Gland of an Ox. A—giant-cells; b—caseous center within the tubercle; c-—fibrous capsule, tissues except possibly osseous tissue and serous membranes. Tubercular lesions of osseous tissue are usually associated with extensive suppuration of the osseous structures, while tubercular lesions of serous membranes are frequently entirely cellular in structure and do not undergo central necrosis. Bovine tubercular lesions are usually encapsulated and become quite extensively calcified. The age of the lesions is sometimes jmportant in medico-legal cases, Calcification usually * begins cod 354 VETERINARY PATHOLOGY. when the tubercle is from six to eight months of age and is ex- tensive by the time the lesion is one year old. Tubercular masses are occasionally observed in the lung, bronchial or mediastinal glands, and in the liver. These masses may contain all stages of tubercular formation or the entire mass may all be in the same stage of development, as liquefying necrosis, caseation or calcifi- cation. Tuberculosis of serous membranes of bovines should receive special mention because of the characteristic appearance of the lesions. Bovine serous membrane lesions vary in size from a millet seed to a walnut, but are usually about the size of a pea. These lesions are frequently thickly studded over large areas of a serous membrane. The nodules are surrounded by a firm cap- sule which causes them to appear as pearl-like bodies, and hence Fig. 185.—Photograph of a tubercular mammary gland, Ox. the name, “pearly disease.’ Sometimes serous membrane tuber- cular lesions are very extensive; this type may be called “mass tuberculosis.” Porcine Tubercular lesions are characterized by enlargement of lymphatic glands, the formation of tubercles of variable sizes in Or upon serous membranes and within the substance of glandular organs, bones and other connective tissues. The tubercles pro- duce increased density of invaded soft tissues and are, therefore, easily detected except in very recent infection. The tubercular nodules in the early stages present about the same color as the surface of the tissue invaded. In sectioning the tubercle the cen- tral portion is caseous and slightly yellow or fibrous and white. INFECTIVE GRANULOMATA. 355 Sometimes there is a combination of both conditions and occa- sionally the tubercles contain calcareous granules. The central portion of porcine tubercles rarely contains liquefied necrotic tissue. 4 Microscopically porcine tubercular lesions are always cellular in the beginning. The cellular tubercles are fairly constant in structure regardless of the tissue in which they occur. The center is at first represented by a mass of lymphoid cells, the other cellular elements occurring as the tubercle develops. Necrosis, or fibrosis, succeeds the cellular stage in the por- cine tubercular lesion. Necrosis of tubercles is probably the result of the activity of very virulent bacteria or the low resis- tance, of the infected animal. The necrotic center may be sur- rounded by a cellular zone (lymphoid and endothelial cells), or it may be surrounded by fibroblasts. The necrotic material is invariably caseated and later becomes calcified. Fibrous lesions vary from the formation of small quantities of fibrous tissue to dense fibrous centers. Fibrous lesions are probably produced by bacteria of low virulence, or occur in ani- mals having a marked resistance. The central portion of the fibrous lesion may become calcified. The so-called arbor vitae gland is a fibrous center in which the fibrous tissue is arranged similar to the trunk and branches of a tree, hence the name. This lesion is observed in the hog in the cervical lymph nodes. The bacterium tuberculosis has been demonstrated in about 30 per cent of arbor vitae glands. The lesions of porcine tuberculosis are in brief either cellu- lar, necrotic and calcified tubercles, or cellular, fibrous and calci- fied tubercles. The lesion is always non-vascular as in other animals. ! Avian tubercular lesions are very similar to mammalian tubercles, and may occur in practically any tissue. Microscopically, avian tubercules are found to contain giant cells, endothelioid cells, small round cells and connective tissue cells, the arrangement of which is the same as described in mammalian tubercles. Avian tubercular lesions have been found in the liver, spleen, intestine, mesentery, kidney, lung, skin, and bones, the frequency being in the order mentioned. Avian tubercles in glandular tissue, i. e., in the liver, kidney, spleen, etc., begin as small, dirty, white cellular foci. They usu- ally occur singly, though they may occasionally become conflu- ent, thus producing nodules a quarter of an inch in diameter. As the tubercles in glandular tissue undergo necrosis, they as- sume a yellowish color. Intestinal tubercles are about the same 356 VETERINARY PATHOLOGY. size as those in glandular tissue. The intestinal lesions are usu- ally quite hard Eine lense and present a glistening appearance. Necrosis frequently destroys the intestinal wall ancl. thus a tuber- cular intestinal ulcer is produced. Mesenteric tubercles are fre- quently pedunculated and they invariably present a pearl like appearance. Extension.—Tuberculosis, except in some cases of the acute form, is essentially a localized disease. However, the disease, even in the chronic form, has a tendency to extend and involve new tissue. The extension may be accomplished by means of, first, the lymphatic system, second, the digestive, respiratory and genito-urinary tubes, third, the blood vascular system and fourth, by continuity and contiguity. Tuberculosis is usually extended by the lymphatic circulation. Thus the first group of lymph nodes through which the lymph passes from a tubercular lesion is almost invariably involved. In fact this is a characteristic of the disease. The large per cent of lymphatic lesions 1s also evidence of extension by means of the lymph. It has been previously stated that hogs are invariably infected by ingestion of tubercular material and in 93 per cent of tubercular hogs the submaxillary lymph nodes are affected, which is further evidence of lymphatic extension. The fact that infec- tion may extend along the digestive, respiratory or genito-urin- ary tracts, has been demonstrated. Thus the discharges, con- taining the Bacterium tuberculosis from a pharyngeal tubercle may pass through the oesophagus and stomach and find a nidus favorable for its development in the intestine. In a like manner the lung tissue may become affected by extension from laryngeal, tracheal or bronchial tuberculosis and prostatic tuberculosis may result from extension of renal tubercular lesions. In extensive or generalized tuberculosis the tubercles not infrequently in- volve and produce necrosis of the blood vessel walls and the virulently contaminated necrotic material being discharged inte the blood resulting in tubercular metastasis. Thus tuberculosis is extended by means of the blood. Extension by the blood in- variably results in generalized tuberculosis which is usually acute. In the discussion of tubercular lesions, the formation of sec ondary and daughter tubercles was mentioned. The production of secondary and daughter tubercles is a means of extension. If the newly formed tubercles are in the same kind of tissue as the primary tubercle then the extension is by continuity. If the secondary or daughter tubercles are in tissues dissimilar to that INFECTIVE GRANULOMATA. 357 i which the primary tubercle occurs the extension is by con- tiguity. In the majority of the cases of lymphatic extension and in some of the cases of blood extension the Bacterium tuberculosis is incorporated in and transported by leucocytes. The leucocytes usually have sufficient vitality to destroy the incorporated bac- teria but occasionally the leucocytes may be destroyed after having transported the bacteria a considerable distance. Thus a Bacterium tuberculosis from a pulmonary tubercle may be incor- porated by a leucocyte and carried to the kidney and the leuco- cyte being destroyed the liberated bacterium may establish a tub- ercular focus in the renal tissue. The occurrence of Bacterium tub- erculosis in the milk of cows having no mammary tubercular lesions as well as the fact that ingestion of tubercular material frequently causes pulmonary tuberculosis, may be due to leuco- cytic incorporation and transportation of the infecting micro- organism. Elimination.—From the sanitary point of view it is always of considerable importance to know the channels or avenues through which infectious agents are discharged in order that they may be destroyed. Tuberculosis affects all tissues and the Bac- terium tuberculosis may not be eliminated from the affected ani- mal or it may be discharged in one or more of the secretions or excretions. It has been determined by the Department of Agri- culture that about 40 per cent of tubercular cattle eliminate the Bacterium tuberculosis in their feces. The same investigators also found, in a limited number of dairies, that about 25 per cent of tubercular cows, regardless of location of the lesions, eliminated the Bacterium tuberculosis in their milk. These are facts of prime importance in adopting means for checking the progress or for suppression of the disease. The discharges from the respiratory tract of tubercular animals frequently contain the Bacterium tuberculosis, especially if they have pulmonary lesions of the disease. The urine and discharges from the female genital organs may be contaminated with the infection. Renal tuber- culosis, however, is not of frequent occurrence and it is not probable that the Bacterium tuberculosis is eliminated in the urine of tubercular animals in which there are no renal lesions. In general the channel of elimination of the bacterium tuber- culosis depends Jargely upon the location of the lesion. Tuberculin and Tuberculin Test.—Tuberculin is a bio-chemic material containing the products and the disintegrated bodies of the Bacterium tuberculosis. It is prepared by growing the Bacterium tuberculosis in glycerine bouillon for a certain length 358 VETERINARY PATHOLOGY. of time. The glycerine bouillon culture is filtered and the fil- trate sterilized by heat and concentrated to the desired strength by evaporation over a water-bath. The active principle of tuber- culin is probably a nucleo-proteid or its chemic derivatives. Tuberculin is a very reliable diagnostic agent. Its chief use in veterinary medicine has been in the diagnosis of tuberculosis in cattle. It is practically as reliable in the detection of human, porcine and probably avian tuberculosis as in the detection of bovine tuberculosis. A tuberculin reaction consists of a local, focal and general or systematic reaction. The local reaction is manifested at the point of injection of the tuberculin and is the reaction evidenced in intradermal and ophthalmic tuberculin testing. The focal reaction consists of a hyperaemia and increased tissue action around the tubercular centers and is probably responsible for the systematic disturbances evidenced in the ordinary thermal or sub- cutaneous tuberculin test. The principal method of application has been by subcutaneous injections and noting the temperature changes in the suspected animal. The normal temperature of the animal is ascertained previous to the injection and the tempera- ture 1s taken every two hours, beginning eight hours after tuber- culination. On the day succeeding the injection a rise of from two to three degrees Fahrenheit is considered a reaction and this sig- nifies that the patient is tuberculous. This reaction is probably due to the specific irritating action of the injected tuberculin upon the tubercular foci producing intense hyperemia around and disintegration of the tubercle. Thus there is a sudden dis- charge of tubercular products into the system and the intense re- action, thermic and constitutional follows. A purified tuberculin used directly in the conjunctival sac is now on the market. The ophthalmic reaction consists of the production of a marked hyperemia of the conjunctiva in from six to ten hours after tuberculination. The intradermal tuberculin test is the official test in the state of Missouri. ACTINOMYCOSIS. Actinomycosis is a specific, inflammatory granuloma, caused by the Cladothrix actinomyces and characterized by the formation of tumorous masses of fibrous tissue in which there usually develops suppurating centers and fistulous tracts. Distribution and extent.—Actinomycosis is prevalent in Eu- rope, Australia, Africa, North and South America. The extent of the disease varies in different countries. According to the 24th Annual Report of the Bureau of Animal Industry there were slaughtered in establishments having federal inspection 7,621,717 cattle, of which 22,742 were found to be affected with actinomy- cosis, or one in about each 340. The actual per cent is even INFECTIVE GRANULOMATA, 359 larger, for many animals afflicted with actinomycosis are slaugh- tered where there is no official inspection maintained. Susceptible Animals—Cattle are more frequently affected with this disease than other animals, though actinomycosis of sheep, goats and hogs is occasionally reported. A few cases have also been observed in the horse, mule, dog and wild ani- mals. Etiology.—A fungus, the Cladothrix actinomyces or actino- myces bovis, 1s the specific cause of actinomycosis. The life his- tory of this organism is not known, but it is thought that it passes a part of its life cycle upon some of the grasses. Each matured fungus is composed of a central body 10 to 40 microns in diameter, from which the radiating filaments (mycelia) extend outward for a distance of from 5 to 20 microns, then becoming enlarged, terminate in club-shaped bodies from 10 to 50 microns in length. Thus the matured fungus has the appearance of a rosette and is commonly called the “ray fungus.” Detached clubs are capable of reproducing the entire rosettes as described. The fungus can be cultivated in artificial media where it develops a tangled mass of mycelia. Source.—The Cladothrix actinomyces is probably most fre- Fig. 186,—Drawing of Actinomyces (Ray fungus) in section of tongue, 360 VETERINARY PATHOLOGY. quently obtained from vegetation, especially wild rye (Hor- dium murinum) consumed by the animal. Infection occurs most frequently in animals fed on dry feed as fodder, stover, straw or hay. During January and February, 1908 .86% or 376 cattle of 41,405 slaughtered had actinomycosis of the tongue or submax- illary lymph nodes, and of 12,484 cattle slaughtered in July, 1908, 44 or 34% were affected with actinomycosis. Some rather exten- sive outbreaks have been investigated in which it seems highly probable that infection has been direct from one animal to an- other, or indirect by means of the discharge of actinomycotic ani- mals that had been smeared on rubbing posts, feed racks and feed troughs. (Of 98 head of cattle, three of which were actinomycotic when placed in the feed lot in November, 42 head were affected with actinomycosis when inspected 2% months later.) Channel of Entrance.—The causative fungus may gain en- trance into the system by way of the digestive tract, the respira- tory tract or through the skin. Abraded surfaces appear to be essential for infection, though it has not been proven that the fungus cannot penetrate uninjured surfaces. The digestive tract is the most frequent channel of entrance in cattle. The tongue, especially the dorsal surface at the junction of the base and apex, is subject to injury by the rough, harsh food consumed by cattle. Tongue injuries may also be inflicted by licking boards, posts, etc., containing nails and splinters. Awns of wheat, barley and rye, chaff, splinters and hair accumulate in the erosions or wounds of the tongue, producing the so-called “hair sores.” More than 12% of 48,000 cattle slaughtered during the winter months in one of the Kansas City packing houses had “hair sores” upon their tongues. The “hair sore” is intimately associated with lingual actinomycosis; indeed it is rare to find actinomycosis of the tongue or submaxillary lymph glands when there is no “hair sore.” Diseased teeth, especially if the gingival mucous mem- brane is involved, also provide an entry for the ray fungus. The possibility of the infection passing through the intestinal or gastric wall explains the cases of peritoneal actinomycosts that are occasionally observed Respiratory infection is not of common occurrence. This type of infection probably occurs by inhalation of chaff or awns con- taminated with the Cladothrix actinomyces. The skin is probably the most frequent channel of entrance in hogs. Actinomycotic scirrhus cords are quite common, the in- fection taking place in the castration wound. Mammary acti- nomycosis is sometimes observed in sows, especially those run- ning in stubble fields, the infection taking place through abra- INFECTIVE GRANULOMATA. 361 sions produced by the stubble. Abrasions resulting from rub- bing on stanchions and feed boxes may be a source of infection in dairy cattle. Lesions.—Macroscopic.—Actinomycotic lesions may be sur- face or subsurface. The fungus may invade and produce the lesion in any tissue. Surface lesions begin as small inflammatory centers which usually thicken and become elevated above the general surface. The lesion gradually increases in size, and in some cases assumes a fungoid appearance. At this stage the lesions vary in size from a small pea to a walnut. The surface tissue may become eroded as a result of the extension of necrosis from the lesion and the typical actinomycotic pus discharged or more frequently the lesion becomes encapsulated by the formation of a dense fibrous capsule. The capsule usually limits the development of the lesion and it may be diminished in size by the contraction of the fibrous tissue constituting the capsule. Subsurface lesions, though beginning as inflammatory centers, are invariably lcircumscribed by, a dense, fibrous wall. As the disease progresses the center of the lesion undergoes lique- fying necrosis. The necrosis extends, producing irregular, tor- tuous sinuses that may extend through the capsule and into the surrounding normal tissue. Ultimately the liquified necrotic tissue (pus) would ordinarily be discharged upon a surface, or the fungus contained in the necrotic tissue (pus) would perfor- ate the primary capsule and cause the production of a,secondary fibrous capsule. Thus the lesion is frequently composed of sev- eral communicating cavities (multilocular) containing actinomy- cotic pus. If such a lesion is incised and pressure applied the typical beads of actinomycotic pus will appear in various places upon the cut surface. Actinomycotic pus is creamy, sticky, tenacious, yellowish-white and contains small, yellow, gritty granules. The pus has a greasy feel and may have a slight odor. If the pus is permanently maintained within the capsule, its fluid content is absorbed and becomes caséous. Osseous actinomycosis is of common occurrence. The fungus having gained entrance produces inflammation, which is suc- ceeded by disintegration of the osseous tissue and the formation of cavities or pockets. By growth and extension of the infect- ing fungus, inflammation and disintegration is favored, and thus communicating cavities are formed in the affected bone. As the process of rarefaction continues within there is new osseous tis- sue deposited without. Thus bone affected with actinomycosis 362 VETERINARY PATHOLOGY. becomes enlarged and cancellous and has a honeycombed ap- pearance. Microscopic—TVhe presence of the Cladothrix actinomyces in a tissue produces an irritation resulting in an accumulation of 187.—From photograph, showing actinomycotic nodules on the dorsum of an Ox tongue, INFECTIVE GRANULOMATA. 363 small round cells, the production of endotheloid and giant cells by the invaded tissue, and finally the development of a fibrous cap- sule around the entire mass. The fungus may appear in the be- ginning as mycelial elements, but later it has the typical rayed appearance. In old lesions the central portion or body of the fungus becomes calcified. Surrounding the clubs or mycelium in the early stages are varying numbers of small, round cells (lymphocytes). As the disease progresses, the matured fungus is more or less surrounded by giant cells that actually contact the fungus. The actinomycotic giant cell is very irregular in shape and: size and has varying numbers of nuclei scattered indiscriminately throughout the cell body. Endotheloid cells appear marginally to the giant cells. These cells are similar in appearance to the endotheloid cell of tuber- culosis, having a relatively large cell body and a small, single nucleus. The small, round cells are first noticed immediately around the fungus, but later they infiltrate the surrounding tissue also, and are in excess of all other cells in the lesion. Fibroblasts appear in the margin of the early lesion, and through their activity a thick fibrous capsule is produced. Actinomycotic pus is found to be composed of tissue shreds and fragments, lymphoid cells and some polymorphonuclear leucocytes, an occasional endotheloid cell and the Cladothrix actinomyces. , Extension.—The extension of actinomycosis has usually been described as taking place only by growth in continuity or contig- uity, or by passing along the respiratory, digestive or genito- urinary tubes. By a careful observation of over 72,000 cattle slaughtered, it has been found that many cases, in which there were “hair sores” but no actinomycotic tongue lesions, showed actinomycosis of the submaxillary lymph nodes. The majority of cases of lingual actinomycosis are accompanied by involve- ment of the submaxillary lymph nodes. That practically all cases of actinomycosis of the submaxillary lymph nodes occurred in animals having “hair sores” is indicative of lymphatic exten- sion. It is therefore quite probable that actinomycosis may be extended in the animal body by means of the lymph. Differential Diagnosis.—Bovine actinomycosis may be con- founded with tuberculosis, nodular disease, abscess formation and various tumors. Tubercular lesions calcify, actinomycotic lesions rarely be- come calcified. Tubercular pus is usually quite different from 364 VETERINARY PATHOLOGY. actinomycotic pus. Tle former is not sticky or tenacious, and does not contain the small, yellow, gritty granules found in the latter. The capsule of an actinomycotic growth is thicker and denser than the capsule of a tubercular growth. The two diseases can be differentiated positively by microscopic ex- amination of the pus and the lesion. The Bacterium of tuber- culosis would be found in tubercular pus and the Cladothrix actinomyces in the actinomycotic pus. Tubercular lesions are characterized by the presence of the horse shoe giant cell, the actinomycotic giant cell is irregular in outline and size, is poly- nuclear, the nuclei being scattered indiscriminately through the the cell body. Nodular disease, though not very prevalent in cattle may be mistaken for actinomycosis. The nodules of nodular disease are in the intestinal wall. The pus in the nodule is greenish yel- low in color, and though fluid in the early stages, it later be- comes caseous but never contains the calcareous granules. Microscopically the finding of the Cladothrix actinomyces in actinomycotic lesions or pus and the absence of this fungus in the lesions of nodular disease is sufficient for differentiation. From abscesses the differentiation may be made by the pecul- iarity of the pus, and the capsule, which is usually much more dense in actinomycotic lesions than in abscesses. Osteosarcomata may produce lesions in bone similar to actin- omycotic lesions. A microscopic examination is always suffi- cient for differentiation of these diseases. Ovine actinomycosis may be confounded with ovine caseous lymphadenitis and nodular disease. Ovine caseous lymphaden- itis is essentially a disease of lymphoid tissue characterized by the formation of greenish yellow pus that later caseates in con- centric layers, but never contains gritty granules. The color of the pus and the arrangement of the caseated necrotic tissue is usually sufficient for differentiation of ovine caseous lymphaden- itis from actinomycosis. The remarks on the differentiation of nodular disease in bovines is equally applicable to ovines. GLANDERS. Glanders is a specific, infective disease, especially affecting equines, caused by the bacterium mallei. Glanders is prevalent in all countries with the possible ex- ception of Iceland, Australia, and some isolated islands. The disease is found in practically all parts of the United States. It is INFECTIVE GRANULOMATA. 365 more prevalent in those portions of a country in which there is extensive horse traffic. ‘The invasion of a province or a country by an army is usually succeeded by the appearance of glanders. Etiology.—Glanders is caused by the Bacterium mallei. ‘This organism was described by several different investigators in 1882. It is similar in appearance to the Bacterium tuberculosis, has rounded ends, is from 2 to 3.5 microns in length and .3 to .5 microns in width. This bacterium occurs singly except that when grown upon potato medium, pairs or even long filaments are not rare. Like, the Bacterium tuberculosis, it produces ple- omorphic forms when cultivated in different media or under varying conditions. In old cultures it frequently becomes short and is sometime coccoid in appearance. Branching forms are not uncommon. It does not form spores. The Bacterium mallei is stained by aqueous solutions of ana- Fig. 188.—Bacterium Mallei, x1000. line dyes that are slightly alkaline in reaction, such as Loet- fler’s methylene blue. It is so-called “Gram negative,” 1. e., it is decolorized by Gram’s solution. Source of Infection.—Infection probably occurs most fre- fluently in an indirect manner, i. e., the infection is obtained from some surrounding object or thing that has been contamin- ated with the infected discharges of a glandered animal. The Bacterium mallei is strictly parasitic and the source of the micro-organism is either the discharges from an infected animal or the carcasses of animals that have died of glanders. Fortunately this bacterium possesses little re- 366 VETERINARY PATHOLOGY. sistance to light, dessication and other external influ- ences and consequently the infection in discharges is as a rule, promptly destroyed. The length of time that the Bacterium mallei may exist outside of the animal body and retain its viru- lency has never been absolutely determined. Authentic cases of glanders have appeared in horses that had been placed in stalls that had been vacant for one year, but prior to that time occupied by glanderous horses. A few reports are indicative of the fact that the Bacterium mallei may retain its virulence in infected buildings for two or even three years, but these re- ports need further substantiation. It seems probable from clin- ical and experimental evidence that, except in the animal body, the virulence of Bacterium mallei is rarely retained longer than one year. In cities, public drinking fountains, hitching posts and feeding troughs are probably the greatest sources of infection. The purchase of second hand harness, wagons, and other equipment should be regulated by ordinances or laws to prevent the spread of such infections as glanders. The Channels of Entrance of the Infection.—All exposed surfaces and natural openings of the body may permit the Bac- terium mallei to gain entrance to the tissues. In glanders, as in tuberculosis it has been quite conclusively demonstrated experimentally that the majority of the cases of glanders results from the ingestion of the Bacterium mallei. No doubt infection may occur by inhalation of the infectious agent, the discharges con- taining the Bacterium mallei becoming pulverized and carried by air currents, and an occasional case may be the results of cutaneous inoculation. Farcy may or may not result from cutaneous infec- tion. Such inoculations are easily accomplished by bridles, harness, saddles, curry combs, etc. More rarely the conjunc- tiva! membrane may be the channel of entrance. For example a horse, affected with nasal glarnders may sneeze or cough and thus infection be forcibly introduced onto the mucous mem- brane of the eye of another horse. Lesions.—Macroscopic—The lesions of glanders are found especially in the mucous membrane of the anterior respiratory passages, lymph nodes, lung and skin, the frequency being in the order mentioned. It is probable that the Bacterium mallei primarily affects lymphoid tissue. The gross lesions may be diffuse or circumscribed, depending upon the virulency of the infecting organisms and the resistance of the affected animal. Diffuse glander lesions are usually found in animals having INFECTIVE GRANULOMATA. 367 little resistance and in which the disease assumes an acute form. In the nasal mucous membrane, diffuse, glanderous les- ions appear as severe inflammation in which the submucosa is extensively infiltrated. The engorgement of the tissue may be sufficient to obstruct circulation and result in necrosis of the mucous membrane thus producing ulcers variable in size and ir- regular in contour. The submaxillary lymph nodes are invari- ably hard and enlarged and may or may not be adherent to the maxilla. Pulmonary, diffuse glander lesions vary in size from a hazel nut to a basket ball and are irregular in shape. These lesions are grayish or dirty white in color. The lesions may undergo a central necrosis or they may become fibrous in nature. The necrotic material may be of a semi-solid or caseous consis- tency and in the smaller foci there may be calcification. In practically all cases of pulmonary glanders the bronchial and mediastina! lymph nodes are enlarged and contain cellular necro- tic or fibrous centers. : Diffuse cutaneous lesions are not of common occurrence. They may be present in acute general glanders, the manifesta- tion in the skin being of the nature of a diffuse gangrenous der- matitis. Cutaneous nodular lesions may become diffuse as a result of rapid and extensive necrosis. Diffuse lesions occur in lymphoid tissue. Splenic lesions are usually nodular though a few cases have been reported in which there were diffuse lesions of the spleen. Osseous lesions are usually diffuse and appear as a supptrative osteitis. Circumscribed or nodular lesions are common in animals that have a marked resistance or in those cases infected with mildly viru- lent bacteria. In chronic glanders the lesions are usually nodular. The appearance of nodular lesions in the nasal, pharyngeal and tracheal mucots membranes as well as in the mucous lin- ing of the facial sinus varies according to the age of the lesion, In the beginning the lymphoid tissue of the mucosa or submu- cosa becomes swollen and the tumefaction is surrounded by a hyperemic zone. As the disease progresses there is necrosis which not only involves the lesion but also the surface tissue, thus producing an ulcer. The size depth and contour of the ulcer necessarily depend upon the extent of the necrosis. In some instances the nasal septum and facial bones may be per- forated. The ulcers vary in size from mere points to areas as large as a silver dollar. The large ulcers are usually the result of two or more necrotic centers becoming confluent. The de- nuded surface is usually limited or surrounded by a ‘raised 368 VETERINARY PATHOLOGY. border, the latter being the result of cellular infiltration. The tissue adjacent to the denuded surface may finally produce sufficient new tissue or granulation tissue to repair the injury. If the necrosis involves only the superficial epithelium the re- pair will be complete and there will be no scar, but if the necrosis has involved the mucosa and portions of the submucosa, Fig. 189.—Nasal septa, showing glanderous ulcers. A A nasal septum from glandered horse. : 1, A crateriform ulcer having a thick raised border with a depressed granulating center. 2. Shows characteristic outline of an ulcer, also fusion of two or more primary ulcers. Thumb tacks. A nasal septum from a second glandered horse. Typical crateriform ulcers and large necrotic area the result of fusion of several ulcers. Cicatrices shown as irregular white spots, Thumb tacks. j reo) tOha ea ice INFECTIVE GRANULOMATA. 369 there will be large quantities of cicatricial tissue produced and consequently a scar. In nodular glanders of the anterior air passages, the submaxillary lymph nodes are invariably enlarged and contain fibrous, caseous or calcified necrotic foci. Pulmonary nodular lesions are usually dirty white in culer and vary in size from pin point centers to masses as large as a man’s head. These nodules in the beginning are entirely cellu- lar and are surrousided by an hyperemic zone. As they become larger the central portion usually becomes necrotic and the hyperemic zone becomes infiltrated with fibroblasts that pro- duce a fibrous capsule. The small nodular lesions may be small and thickly distributed throughout the entire lung. The large Fig. 190.—Cutaneous Glanders—Farcy, < 1. A large erosion or ulcer (farcy bud) on the internal surface of fetlock, 23 and 4. Other ulcers appearing along the sub- stance that destroys tissue. More violent than corrosive. ~ The 378 GLOSSARY. Cellulose (L.Cellula, a small cell and Clonic (Gr.Klonos, commotion.) Char- osis, a condition of.) The principal acterized by spasmodic and convuls- constituent of cell-membranes. ive muscular contractions alternat- Cementum (L.Caementum, a _ rough ing with relaxations. stone.) A plastic material capable Clot (A.S.Clate, a burr.) A special soli- of becoming hard and of binding dification of the blood outside of a together contiguous materials. vessel. Centrosome (Gr.Kentron, center and Coagulated (L.Coagulare, to curdle.) A Soma, body.) A structural part of condition in which there is a coag- a cell in active mitotic cell-divi- ulum., ap iers Coagulum (Coagulare, to curdle.)