Chapter I: Part 1

TEXT BOOK
OF
VETERINARY MEDICINE

BY

JAMES LAW, F.R.C.V.S.

Director of the New York State Veterinary College Cornell University,
Ithaca, N. Y.

VOL. I

ITHACA
PUBLISHED BY THE AUTHOR
1896

Copyright by
JAMES LAW
1896

PRESS OF
ANDRUS & CHURCH
ITHACA, N. Y.

PREFACE.

During a long experience in teaching veterinary medicine and surgery in Cornell University, the author felt the urgent need of a compend on the subject, written from the American standpoint and having special reference to the American live stock industry. This led to the production of the Farmer’s Veterinary Adviser, which has been well received, and has, up to the present, passed through ten editions in the United States, besides the unauthorized editions published in Canada and Great Britain.

In entering upon a larger field as Director of the New York State Veterinary College, and professor of medicine and sanitary science, he aims at producing a work which will meet the needs of the American student and practitioner. The special phases of animal pathology in America, the diseases peculiar to our soil, and the parasites that prevail here, but are unknown in Europe, demand consideration from the American point of view. The special features of our breeding, grazing and feeding industries, and of the dairy, over our great extent of territory, and the varying influence of soil, water, climate, altitude and traffic, the scope and limitations of our interstate traffic, and our special relation to the old world in the matter of meat products, combine with other conditions in demanding a somewhat different treatment of the subject from that which we find in European publications. Then, too, the recent extraordinary advances in the field of bacteriology and sanitary science, which have virtually revolutionized modern medicine, and are an earnest of still greater advances in the near future, demand a work which shall, as far as possible, set forth the present advanced status, and thus lay a solid foundation to intelligently follow, if not to lead, in the imminent advance. As a contribution to this, the present volume, the first of a series, is offered to students, practitioners and scientists by their friend,

THE AUTHOR.

New York State Veterinary College,
Cornell University.
October, 1896.

CONTENTS

PREFACE. CONTENTS. OBJECTS AND METHODS OF STUDY. ETIOLOGY CAUSES OF DISEASE. MEDICAL DIAGNOSIS. SYMPTOMATOLOGY. SEMEIOLOGY. PROGNOSIS. PROPHYLAXIS. PROPHYLACTICS. PREVENTION. THERAPEUTICS. TREATMENT. HYPERÆMIA. CONGESTION. INFLAMMATION. PHLOGOSIS. PHLEGMASIA. FEVER. DISEASES OF THE RESPIRATORY ORGANS. DISEASES OF THE NOSE. RHINITIS. CORYZA. NASAL CATARRH. COLD IN THE HEAD. SIMPLE CORYZA IN CATTLE. CHRONIC NASAL, CATARRH. NASAL GLEET. OZŒNA IN THE HORSE. COLLECTION OF PUS IN THE NASAL SINUSES. ABSCESS OF THE FALSE NOSTRIL OR TURBINATED BONES. NASAL DISCHARGE FROM CARIOUS TEETH, ETC. COLLECTIONS OF PUS IN THE GUTTURAL POUCHES. NEOPLASMS IN THE HORSE’S NOSE. CATARRH OF THE FRONTAL SINUSES IN CATTLE. CATARRH FROM TRAUMATISM. CHRONIC CATARRH OF CATTLE. MALIGNANT CATARRH OF CATTLE. PARASITIC DISEASES OF THE NOSE. COCCIDIAN CATARRH IN RABBITS. LARVA OF ŒSTRUS OVIS (GRUB) IN THE NASAL SINUSES OF SHEEP. NASAL CATARRH IN DOG AND HORSE FROM LINGUATULA (PENTASTOMA) TAENIOIDES. RHINARIA TAENIOIDES. AFFECTIONS OF THE THROAT. LARYNGITIS IN THE HORSE. PHARYNGO-LARYNGITIS IN CATTLE. LARYNGITIS IN SHEEP. LARYNGITIS IN PIG. LARYNGITIS IN THE DOG. PHARYNGITIS. SORE THROAT. CROUP. PHARYNGEAL AND LARYNGEAL POLYPI. DYSPNŒA LARYNGEA. ROARING. HEMIPLEGIA LARYNGEA. ŒDEMA GLOTTIDIS. LARYNGEAL HYPERÆSTHESIA. CONVULSIVE COUGH. INFECTIOUS DISEASES OF THE THROAT. GUTTUROMYCOSIS OF SOLIPEDES. DISEASES OF THE CHEST. RELATIVE POSITION OF THE LUNGS, HEART AND OTHER ORGANS IN THE DIFFERENT DOMESTIC ANIMALS. PERCUSSION. AUSCULTATION. DISEASES OF THE LUNGS. BRONCHITIS. CHRONIC BRONCHITIS IN THE HORSE. BRONCHIAL CATARRH. BRONCHITIS IN THE OX. BRONCHITIS IN THE DOG. CROUPOUS BRONCHITIS IN CATTLE AND SHEEP. ACUTE CONGESTION OF THE LUNGS. PULMONARY HYPERÆMIA. PULMONARY ŒDEMA. ATELECTASIS. COLLAPSE OF LUNG. HÆMOPTYSIS. PULMONARY APOPLEXY. HÆMORRHAGIC INFARCTION. PNEUMONITIS; PNEUMONIA; INFLAMMATION OF THE LUNGS. ACUTE CROUPOUS PNEUMONIA. PNEUMONITIS IN THE HORSE. CROUPOUS PNEUMONIA IN THE OX. CROUPOUS PNEUMONIA IN SHEEP. PIG. PNEUMONIA. DOG. PNEUMONIA. ACUTE PLEURISY IN THE HORSE. PLEURITIS. PLEURISY IN CATTLE. PLEURISY IN SHEEP. DOG. PLEURISY. PLEURO-PNEUMONIA. BRONCHO-PNEUMONIA. BRONCHO-PLEURO-PNEUMONIA. HYDROTHORAX. PNEUMOTHORAX. AIR OR GAS IN THE PLEURA. PYO-PNEUMOTHORAX, EMPYEMA. CHRONIC PLEURISY. PLEURODYNIA. BRONCHIAL ASTHMA IN THE DOG. ASTHMA. BROKEN WIND. HEAVES. DYSPNŒA. POLYPUS OF THE BRONCHIAL TUBES. DISEASES OF THE BRONCHIAL AND MESENTERIC GLANDS. PARASITES OF THE AIR PASSAGES, LUNGS, AND PLEURA. DISEASES OF THE HEART AND ORGANS OF CIRCULATION. PALPITATIONS. ANGINA PECTORIS. BREAST PANG. FUNCTIONAL IRREGULARITY IN THE RYTHM OF THE HEART. CONGENITAL MALFORMATIONS AND DISPLACEMENTS OF THE HEART. HYPERTROPHY OF THE HEART. ATROPHY. DILATATION OF THE HEART. INFLAMMATIONS IN THE HEART. PERICARDITIS. ENDOCARDITIS. CARDITIS. MYOCARDITIS. CHRONIC VALVULAR DISEASE OF THE HEART. FATTY DEGENERATION OF THE HEART. NEW FORMATIONS IN THE HEART. TUMORS. PARASITES. RUPTURE OF THE HEART. DISEASES OF ARTERIES. THROMBOSIS AND EMBOLISM. ANEURISM. ARTERIO-SCLEROSIS. ANGEIOMA. CIRCOID ANEURISM. ANEURISM BY ANASTOMOSIS. VENOUS TUMOR. NŒVUS. PHLEBITIS. VARICOSE VEINS. DILATED VEINS WITH ALTERED WALLS. PHLEBOLITES. CALCAREOUS BODIES IN THE VEINS. HÆMORRHAGE. HÆMOPHILIA. DISEASES OF THE BLOOD. PLETHORA. POLYÆMIA. HYDROÆMIA. ANÆMIA OLIGÆMIA. PROGRESSIVE PERNICIOUS ANÆMIA. IDIOPATHIC ANÆMIA. CHRONIC ANÆMIA. DROPSY IN CATTLE AND SHEEP. MELANÆMIA. BLACK PIGMENT IN BLOOD. LEUKÆMIA. LEUCOCYTHÆMIA. LYMPHADENOMA. HODGKIN’S DISEASE. ACUTE LYMPHANGITIS OF PLETHORA IN HORSE. ANGEIOLEUCITIS. INFECTIVE LYMPHANGITIS. TRAUMATIC LYMPHANGITIS. LYMPHANGIECTASIS. DILATED LYMPHATICS. LYMPHORRHŒA. LYMPHORRHAGIA. DISCHARGE OF LYMPH THROUGH WOUNDS OR SORES. LYMPHADENITIS. INFLAMMATION OF THE LYMPH GLANDS. INDEX.

VETERINARY MEDICINE.

OBJECTS AND METHODS OF STUDY.

Pathology—general—special. Morbid anatomy. Pathological chemistry;
Disease. Health. Death—Somatic—partial—necrosis. Syncope. Apuœa.
Asphyxia. Coma. Death from old age.

The principles and practice of Veterinary Medicine should embrace all that is known of the causes, nature, symptoms, prevention and cure of disease in domestic animals. Incidentally it includes diagnosis and prognosis.

=Pathology= is the science which tells of the causes, and nature of disease, and the functional and structural changes by which it is characterized. In modern usage the term pathology is understood to refer to the intimate nature of disease, but this necessarily involves an enquiry into its sources and the predispositions to its occurrence; its phenomena whether in changes of function or structure; and its results in the form of perverted function, structural changes, degenerations, dependent disorder, etc. The field of pathology is further divided into general pathology and special pathology.

=General Pathology= treats of disease processes in their generic form, and as they appear in many different diseases. Thus inflammation and fever are the prominent phenomena in a great many different diseases which differ in their seats, their causes, manifestations and results. Inflammation and fever are therefore subjects of general pathology. Similarly all forms of degeneration—fatty, fibrous, calcic, amyloid, etc., are disease processes found in many different organs and under very varied conditions and they are accordingly included in general pathology. Hypertrophy and atrophy are also possible in every organic tissue irrespective of kind or seat, they belong therefore to this particular field.

=Special Pathology= on the contrary is confined to a particular disease and not only elucidates the causes, phenomena and results of such disease, but seeks to do this in such a way as to differentiate this malady from all others however closely related to it. Thus inflammation of a bone is known under the general name of osteitis, this may be due to a great variety of different causes, and each would have its own special pathology. The osteitis of simple mechanical injury is essentially different from the osteitis of rheumatism, of purulent infection, of tuberculosis, of actinomycosis. So with the inflammations of every other tissue. Each may suffer from a variety of inflammations, springing from different causes, attended with characteristically unlike tissue changes and tending to different issues, and every one of these forms has therefore its own special pathology.

=General Pathology= may be said to deal with typical disease processes to a large extent irrespective of the individual disease in which they may appear, while =Special Pathology= deals with the morbid phenomena which distinguishes the individual malady from all other diseases however closely allied to it.

=Pathological (Morbid) Anatomy= deals with structural changes, the cause, the accompaniment or result of disease. These morbid changes are microscopic or macroscopic. Both constitute morbid anatomy, but the microscopic alterations come under the special name of morbid (pathological) histology.

=Pathological Chemistry= is that branch of pathology which treats of chemical changes produced by disease in the blood, lymph, tissues, secretions and excretions. It demands a previous knowledge of the condition of these tissues and fluids in health, in the particular genus of animal and under the same dietary and environment. Physiological Chemistry is therefore an essential prerequisite to pathological chemistry, just as anatomy, physiology and histology are indispensable to the appreciation of pathology and morbid anatomy.

=Disease= is an injurious deviation from the normal function or structure. The morbid process resulting in disease is usually in the nature of a modification of the normal or physiological condition, so that it is often difficult to set the exact limits of health and disease. What is a purely physiological process under given conditions, would be distinctly pathological under others. The free kidney secretion of cold weather and the profuse perspiration of a hot season are both purely physiological and in the main balance each other. Each under its special environment fulfills an essential work in eliminating from the system toxic materials which would prove hurtful if retained, and thus each is not only physiological but beneficial. If, however, they occurred, not in this mutually compensatory manner, but simultaneously in this profusion, they might well be dreaded as morbid conditions. Again if either were to occur apart from its normal causative environment, if for example the polyuria appeared in hot weather and the perspiration in cold, the phenomenon might fairly be called pathological. In any case if the excessive secretion induced a lowering of the general tone of health the process would be essentially a morbid one. In pronouncing therefore upon a morbid process one must take fully into account the corresponding physiological process, the attendant conditions, and whether the result is injurious or otherwise.

The same is true of structural changes. What under given conditions would be essentially a morbid structure, might under other conditions be a simple adaptation to an unwonted environment, and a means of protection from injuries that would otherwise accrue. Excessive growth of cuticular tissue in the epithelioma, wart or corn is injurious and essentially pathological, while the callus on the camel’s knee or the workman’s palm is purely protective and physiological. The local development of a mass of fatty tissue in the average man or beast is a disease, but the tendency to the uniform deposition of fat in the connective tissue of the improved breeds of meat producing animals, is the happy culmination of a long continued and skillful selection and regimen, without which the live stock industry of today would be a grievous failure. To constitute disease, therefore, modified function must be permanent, and not simply a compensating increase, decrease, or other change, and it must be in some way injurious to the animal economy. Similarly to constitute disease modified structure must be other than a simple protection or beneficial change, it must not be a simple evolution in the nature of accommodation to the environment but it must be a cause of injury to function or a distinct deformity.

=Health= may be said to be the harmonious exercise and mutual balance of all the bodily functions, and any interference with such mutual exercise or balance may be said to constitute disease. But as health passes into disease by insensible gradations, there is of necessity an extensive borderland which often cannot be allotted to one condition or the other, but which must often be left a disputed territory.

Again certain animal constitutions are innately strong and robust, while others are weak and feeble, yet the delicacy of the latter cannot be set down as actual disease, and by maintaining a due balance between the functions, a fair measure of health and even long life may be secured.

=Death= as the result of disease may be either _partial_ or _somatic_.

=Partial= or =local death= may be _molecular_ as in =ulceration=, or it may affect an organ or part of an organ, as in =necrosis=, =sphacelus=, or =sloughing=. =Somatic death= is a loss of vitality of the entire body and is manifested by a complete cessation of the bodily functions, including that of nutrition. Usually the arrest begins with one of the great vital processes, in advance of the others, and thus in different cases, we have _death beginning at the heart, at the lungs, and at the brain_.

=Death from syncope or fainting, begins at the heart=, which loses its irritability or contractility, or is seized with a tonic spasm. If there has been lack of contractility, the heart is found after death in a flabby, soft condition, and quite frequently filled with blood. If heart-spasm, it is contracted, firm, and empty or nearly so. Syncope may result from severe nervous shock (emotional), from the electric current, from insolation, or from heart sedatives like chloroform, or nicotine. It may, however be but the culmination of a gradually advancing debility, from exhausting diseases, from fatty degeneration of the cardiac muscles, or from starvation, or anæmia. Again the exhaustion coming from profuse hæmorrhage, or from violent over-exertion is a cause of fatal syncope.

In =death beginning at the lungs= (apnœa, asphyxia, or suffocation), the blood failing to receive oxygen and to give up its carbon dioxide is unable to maintain the various functions of the body and the arrest of the other vital processes speedily follows. The arrest of the respiratory process may occur from nervous shock, but more commonly it results from choking, strangulation, drowning, or the action of irrespirable gases. In diseases of the heart and lungs it is liable to occur from the obstruction of the pulmonary circulation and from the depression of the respiratory nervous centres. After death the lungs are found gorged with dark red—almost black—blood, which likewise distends the right heart and systemic veins, and all mucous and serous membranes have a dark red, congested aspect. When breathing has been arrested by mechanical violence there are, first, active contractions of the respiratory muscles, but no loss of consciousness; then as the brain becomes charged with venous blood, consciousness and volition are lost and convulsive movements ensue. Later still there is no respiratory effort nor convulsions, but the heart continues to beat for two or three minutes longer.

=In death beginning at the brain= (Coma) the sensory functions fail first, as evidenced by drowsiness, stupor, or complete insensibility, while the movement of heart and lungs are still temporarily continued. Pressure on the brain by a fractured bone or blood clot, or in cases of violent congestion or the rapid growth of tumors, usually operates in this way. It may also result from the direct action of certain poisons, like opium, belladonna, or chloroform, or the ptomaines or toxins of bacteria. Causes acting on the brain may, however, lead to death by syncope or asphyxia when the nerve centres presiding over circulation or respiration are the first to feel the full effects of the pressure or poison.

=Death from old age=, with a gradual failure of the natural processes of nutrition and tissue-growth, and the occurrence of atrophy and various degenerations of the organs is not a common occurrence in domesticated animals, so that it may be dismissed without further notice.

_Actual somatic death_ is marked by the cessation of breathing and pulse, the dilated pupils and semi-closed eyelids, the coldness and pallor of the visible mucous membranes and skin, and the clenching of the jaws with slight protrusion of the tongue. Yet these symptoms may be present in syncope and it may even be impossible to detect the beats of the heart, though the subject still lives. Pressure of the finger on a white portion of the skin or on a mucous membrane may give a further indication. If the indentation made by the finger is slowly effaced and if the blood again slightly reddens the part the presumption is against death. Even this is not infallible, since by pressure of gas in the internal cavities or deeper blood vessels, the blood may be forced back into the surface capillaries giving an appearance of circulation, after actual death. On the other hand any exudation or œdema will retain the imprint of the finger even in life. The general relaxation of the muscles and their lack of response to electric stimulation, and the setting in of cadaveric rigidity, and later still of putrefaction give more conclusive evidence of dissolution.

ETIOLOGY: CAUSES OF DISEASE.

Causes—simple—complicated: Proximate; Remote: Predisposing—race,
genus, family, heredity, individual, environment, food, age, sex,
temperament, idiosyncrasy, debility, plethora, interdependence of
organs, embolism, mechanical influence. Exciting causes, intrinsic,
extrinsic, inherent, acquired, heredity, dentition, heat, cold,
atmospheric conditions, electricity, moisture, dryness, dust,
darkness, light, soil, food, water, inaction, over-exertion,
mechanical causes, poisons,—mineral—vegetable—animal, microbes,
contagious, infectious, epizootic, enzootic, sporadic, panzootic,
zymotic, mediate contagion, bacterial poisons.

The causes of disease are simple or complicated, and in the latter case a single factor may be altogether harmless unless associated with another which also may have been innocuous alone. For example: the infecting germ of glanders (Bacillus Mallei) is harmless to the ox which lacks the predisposition to the disease:—feeding buckwheat is harmless to the dark-skinned animal, but is injurious to the white-skinned, if exposed to sunshine:—the chicken can bear with impunity exposure to cold or to the bacillus anthracis, but it cannot endure these two etiological factors combined. It follows that one cannot predict the same result from the same cause in every case. Yet with all concurrent conditions the same the result will follow with mathematical certainty. This will serve to illustrate the value of thoroughness in etiological knowledge, as the basis of a sound pathology.

Etiology is primarily divided into =proximate= and =remote=. _Remote_ causes are again divided into =predisposing= and =exciting=.

=Predisposing Causes= are such as induce a condition of the system or of a particular organ or group of organs which renders them specially susceptible to a disease. This may be a characteristic of the _race_ or _genus_ of animal, thus the genus bovis alone suffers from lung plague, the genus equus from dourine, and ruminants from Rinderpest. It may be a _family trait_, (_hereditary_) hence we see certain families of both men and cattle cut off by tuberculosis, while other adjacent ones largely escape. It may be an _individual peculiarity_, thus some subjects have a congenital insusceptibility to a given disease, from which others of the same family suffer, and one who has passed through a self-limiting disease like measles, cowpox or anthrax is rarely attacked a second time. Again predisposition may be due to _environment_ as when we find herds in damp and exposed localities obnoxious to rheumatism, and horses in dark mines exposed to specific ophthalmia. It may be the result of _food_ as when the flesh-fed fox or rat resists anthrax and the farina-fed one falls a ready victim. _Age_ may predispose, early youth being remarkably susceptible to parasitism and bacteridian infection, and old age to fractures and degenerations. _Sex_ is inevitably a cause of limitation of disease as the females and males can only suffer from disease of their respective =sexual= organs. Again of diseases common to both sexes certain nervous and digestive disorders are common in connection with gestation, and certain calculous diseases in connection with the long and narrow urethra of the male. _Temperament_ has a marked influence, thus the sanguineous or nervous race horse or hound shows a marked predisposition to diseases of the heart, lungs and brain, and to a sthenic type of inflammation and fever, while the heavy lymphatic draught horse has a proclivity to diseases of the lymphatics and skin. _Idiosyncrasy_ is closely allied to temperament, but the condition may be less manifest, and the peculiarity is only recognized by the results, as when a man is poisoned by sound fish or raspberries. _Debility_ whether from deficiency or poor quality of food, on the one hand, or from overwork, filth, dampness or disease on the other must be looked upon as strongly predisposing to certain diseases, such as tuberculosis and glanders. _Plethora_ which charges the blood and tissues in a different way with effete organic products, lays the system especially open to certain diseases like black quarter in young cattle, and parturition fever in cows. _Disease of one organ_ often predisposes another organ through interdependence of function, as when torpid or congested liver leads to portal and intestinal congestion, diseased teeth to digestive disorder, imperfect hæmatosis to kidney trouble; in other cases blood clots or bacteria from one pathological centre may be arrested in the blood vessels of a distant organ and start new foci of disease (embolism, metastasis); in still other cases the impairment of the healthy function in one organ acts injuriously on another, as when emphysema or other disease of the lungs forces the blood back upon the heart causing dilation with atrophy of the walls. _Previous disease in a tissue_ leaves for a time an impairment of structure and function which may become the essential predisposing cause of the effective operation of a morbific factor. _Mechanical_ action on a part may predispose to disease, as for example, by reducing its circulation and nutrition and thereby directly impairing its power of resistance to other inimical agencies. Not infrequently a pus microbe lies deep in the cuticle or even in the tissues without harm, until there occurs a bruise, or a bony fracture when it at once develops a focus of purulent infection (abscess).

=Exciting Causes= are the immediate causes of particular diseases. Like the predisposing causes they may be _intrinsic_ or _extrinsic_, and the first may be =inherent= or =acquired=.

Among =inherent= causes are certain of those already named as predisposing causes, but which have come to be forcible enough to develop disease without the intervention of any other observable factor. Thus a _hereditary_ monstrosity (redundancy or defect), will appear in successive generations without any apparent additional cause. The appearance of white calves in herds of black cattle, after the whitewashing of their stables shows a similar hereditary operation though the result is not in this case pathological. The birth of blind foals from blind sires or dams, or of foals with distorted feet from mares suffering from severe chronic foot lameness are true pathological sequences, in which the exciting cause is hereditary and operates during intrauterine life. _Dentition_, as an attendant on early life is often a directly exciting cause, from direct injury by entangled or retained teeth that should have been shed, by fever aroused by the active local changes, or imperfect mastication or insalivation leading to consequent indigestion; in puppies and kittens convulsions are not uncommon as a result.

=Extrinsic Causes= are such as operate through the environment. _Heat_, if excessive and prolonged, relaxes and exhausts the system and exerts a direct influence on the process of sanguification so that it may become the direct cause of a variety of diseases. As the result of extensive burns, dangerous congestions of internal organs are liable to occur, and even the prolonged heat of summer often superinduces hepatic and gastric disorder, diarrhœa and dysentery. Fat cattle in uncovered cars or yards under a hot sun and with no breeze suffer extensively from insolation, the temperature of their bodies rising to 110° to 112° Fah. and even higher. _Cold_ is equally potent. With a temperature below zero Fah., the iron bit will freeze the buccal mucous membrane, and cause extensive erosion of the mouth. The cold of salted snow or ice will freeze the feet, causing sloughing of the skin above and around the coronet and shedding of the hoofs, and predisposing to fatal septic infection of the wounds. On the system at large, cold causes retrocession of the blood upon the internal organs, and endangers the occurrence of acute disease in any structure which is already debilitated or otherwise susceptible. The nervous effect of the chilling of the skin is often the unbalancing factor which sways the scale in favor of disease, which the system was able to resist until this disturbing element was introduced. The sudden chill from passing out of the warm barn into the frosty air, from plunging into icy water, from standing in cold rain or sleet, from standing in a draught of cold air especially when perspiring, is a fruitful source of many diseases. In the cow, lying with the udder on a cold stone may be the starting point of mammitis. The effect of sudden chill is well exemplified in the great prevalence of diseases of the respiratory organs at the change of the seasons in spring and autumn when the vicissitudes of temperature are greatest, and the system unprepared by habit, to bear the sudden change. Again it must be noted that exposure to cold has a tendency to cause disintegration and solution of the red blood globules, and that certain animals are especially susceptible to this influence. _The condition of the atmosphere_ is often a direct cause of disease as when charged with offensive or irritating gases, the result of decomposition of organic matter, with sewer or cesspool emanations, with deleterious gases from chemical works, telluric sources, or fires. A low state of health, a local irritation in some part of the air passages, or even a speedy asphyxia may be the outcome of such atmospheric conditions. Again the presence of solid particles of a more or less irritant, septic or infecting kind prove the starting point of various diseases. The stone cutters’ phthisis, and the sand granule ophthalmia are familiar examples of the irritant, which often acts through the dust of the highway. Of the infecting particles we have the germs of cattle lung plague, of infective ophthalmias, and of tuberculosis carried with the dry dust and inhaled. Of toxic agents borne on the atmosphere we see the compounds of arsenic, mercury and lead. Moisture and dryness of the air induce respectively a lymphatic constitution and low tone of health, and a nervous constitution and a tendency to neurosis, ophthalmias, and skin diseases. The pressure of the atmosphere has a profound effect on animal health as seen in the extreme troubles of the heart and circulation in the diving bell, and the respiratory, hæmorrhagic and brain affections of high attitudes. A low barometer is attended by nervous disorders (neuralgia) (S. Weir Mitchell). Surgical operations do best with a high or rising barometer (Adinell, Hewson). The electrical tension of the atmosphere shows familiarly, in man, in the feeling of heaviness, dullness and malaise that precedes the bursting of a thunderstorm and the relief that follows its termination. To this influence many of the domestic animals are incomparably more sensitive than man, as witnessed in the disposition of swine to hide in their pens or under litter on the approach of the storm, the nervous disturbance even to abortion of certain ewes which are heavy in lamb, and the great discomfort and even piteous cries of some domestic felines on such occasions. The greatest electric tension is seen in the drier climates, where the air, robbed of its moisture, proves a poor conductor and equalizer, and the positive and negative electricity get stored up separately in air, cloud and soil. The presence of ozone in the air, as a habitual concomitant of electric discharges, has been supposed to be a disturbing influence, since it is distinctly irritating to the mucous membrane when present in excess, but such excess apart from its artificial production is highly improbable. As habitually met with it is antiseptic and health giving. _Darkness_ always deteriorates the general health, producing bloodlessness and pallor. _Light_ is usually invigorating, yet bright sunshine falling upon the eyes from a window in front of the stall, or in the open air when the face is turned up by an overdraw check rein, or reflected from white dust and, above all, from snow, will often induce inflammation and blindness. _Soils_ are often potent etiological factors. Dense, damp, cold, undrained soils, are habitually covered by a stratum of cold air, saturated with moisture, which greatly lowers the vital stamnia. Damp clays, and waterlogged soils of various kinds, rich in organic debris, are the natural homes of various pathogenic microbes, such as those of ague, anthrax, milk sickness, actinomycosis and yellow fever. Well drained sandy or gravelly soils are usually healthy, unless they contain a great excess of decomposing organic matter. Again soils with an excess of alkaline or other mineral matter may prove deleterious, and those on the magnesian limestone often harbor the poison of goitre, and cretinism, and favor the occurrence of urinary calculus. _Faulty food and feeding_ in the domestic animals are chargeable with many diseases. Stock often fall off in condition, in the hands of one feeder, when the same food given with regularity and judgment by a more careful feeder would keep them in the highest health. Hay and grain which is musty and filled with cryptogams and their products, are common causes of disorder of the stomach, the kidneys, the nervous system or of general nutrition. Smut and ergot at certain stages of their growth or grown under given conditions cause nervous disorders, abortions, and gangrene of the extremity. A long list of vegetable poisons may mix with fodders, and animal poisons with the food of the Carnivora. A number of standard fodders may be poisonous at certain stages of growth, as partially ripened perennial rye grass, millet, Hungarian grass, vetches, etc. _Water and deprivation of water_ are fertile causes of illness. Ruminants cannot chew the cud when deprived of water, hence impaction of the first and even of the third stomach with fermentations, tympany and other disorders. Horses suffer more from a full drink of water after a feed of grain, the unchanged albuminoids being carried on into the intestines, and both gastric and intestinal indigestion induced. Sheep suffer fatal fermentations after drinking the alkaline water of the Plains; cattle have diarrhœa and dysentery from selenitions, or from stagnant and putrid water; and the water from the dolomite is the usual channel of the goitre poison. Certain germs like the plasmodia of malaria, and comma bacillus have their natural home in impure water, and others like anthrax bacillus survive in the mud and silt at the bottom of wells, ponds, and rivers and enter the system in the water. _Compulsory rest_ in a stall often induces torpor of liver and bowels, general muscular debility, and fatty degeneration especially of the liver and heart. A few months of the swill feed, hot atmosphere and absolute rest in a distillery stable usually ruins cattle for stock purposes. _Overexertion_ on the other hand is prolific of illness. Exhaustion of the muscles, congestion, inflammation, cramps, congested lungs, heart failure or rupture, apoplexies and other hæmorrhages are among the resultant maladies. Auto-poisoning is another result shown in equine hæmoglobinæmia, and the fever of leucomaines. The excessive development of sarcolactic acid from muscular work may render an insusceptible animal susceptible to the anthrax bacillus. _Mechanical causes_ would include over-exertion, in the production of strains, fractures, and other injuries. They would also include impaction by foreign bodies, calculi, and ingesta, friction of folds of skin or by harness and other objects and pressure which leads to absorption and atrophy. To these must be added _poisons of vegetable, mineral and animal origin_ and the _microörganisms_ which act as injurious ferments within the animal body. These will be treated more fully later on. Of the microörganisms it may be said here, that they are almost certainly the cause of all transmissible diseases. These diseases are variously named on the basis of different ideas. They are =enthetic=, that is implanted as a seed is planted in the ground to grow and multiply. They are =zymotic= or fermentative because the essential cause multiplies and is propagated like a ferment. They are =contagious= because propagated by contact mediate or intermediate. They are =infectious= when transmitted, not alone by contact but through the atmosphere. They are =epizootic= because they tend to attack animals generally or a given genus or family of animals generally when these are exposed to the infection. They are =enzootic= when confined to the animals in a given locality, the soil or conditions of which are favorable to the preservation of the germ in pathogenic potency, or to the production of a special susceptibility in the animal system. They are =sporadic= when each case occurs without any casual relation to another. They are called =panzootic= when they attack all animals without apparent preference. The term _panzootic_ is also used to describe those recrudescences of a disease or cycles of exalted pathogenesis which are observed in contagious diseases, which frequently last for years and again give place to a period of benignancy. Such cycles, of malignancy and benignancy, may be due to modified environment acting either on the disease germ or the animal system, or on both simultaneously.

The terms =enthetic=, =zymotic=, and =contagious= best express modern views of the nature of these maladies. The term =infectious= when used to express a gaseous or otherwise intangible (unorganized) body, or influence transmitted through the air, necessarily excludes the particulate, living, self-propogating germ upon which the transmissibility of the disease depends. A chemical, electrical, or other body or influence generated outside the animal body, cannot well be conceived of as reproducing itself within the animal body but must act like any other ectogenous poison, according to the size of the dose and the frequency of its exhibition. This might create an _enzootic_ disease but would lack all the qualities of a contagious affection since it could not spread from a victim when taken elsewhere and turned among animals which would prove equally susceptible if placed within the infecting area. Suppose on the other hand we apply the term _infectious_ to diseases in which the levity of the particulate living germ allows of its being inhaled into the body of the susceptible animal, the case becomes one of simple _mediate contagion_, the air acting as the intermediate bearer.

The term =zymotic= conveys a clear idea of the method of increase of the disease germ in the body by the ordinary process of generation. The old doctrine of fermentation by a continuous change, due to contact with dead fermenting matter, as an inflammable body continues to burn by contact with the incandescent portion, has been definitely disproved by the investigations of Pasteur and others, and today we must recognize that every fermentation is the result of the propogation and vital activity of living organisms. This does not ignore that the chemical products or enzymes which are constructed by the vital activity of the microbes, will dissolve or transform organic matter, but in the absence of the microbe no such enzyme can reproduce nor multiply itself and its action must therefore be exactly limited by its amount. The living germ itself is therefore the one effective factor, by which the contagious disease may be maintained and propagated. In its turn the living germ can only come from a pre-existing living germ. To the scientist of today the doctrine of spontaneous generation is a thing of the past and the aphorism _omnis ovum ex ovo_ is dominant. The argument drawn from the saccharizing of starch in the germinating seed by the operation of diastase is inapplicable, as the diastase is produced by the living cells of the germinal part of the seed, which are thus the counterpart of the disease germ. No such glycogenic action occurs in the seed that has been boiled or otherwise robbed of its vitality. So with the arguments drawn from the ptyaline of the saliva, the pepsin of the gastric juice, and the trypsin of the pancreatic juice; each of these is the product of the living cells of the gland by which it is secreted, and cannot increase its own substance in the absence of these cells. Like the enzyme of the bacteridian ferment, these gland products can break down or digest certain organic matters, but in all alike, the only source of the chemical solvent is the living bacterium or gland cell from which the particular product is derived. The toxins of a virulent liquid, after the sterilization of the latter may still produce most of the lesions and morbid phenomena of the disease, but, although death were to ensue, the body of the victim would not be infecting to other susceptible animals. The parallel between the functions of the secreting animal cells and the disease germs may thus be put in tabular form:

Living Source. Chemical Product. Result.

Salivary gland cells = Ptyaline = Starch changed to
Sugar.

Peptic gland cells = Pepsin = Albuminoids changed
to peptones in acid
solutions.

Pancreatic gland cells = Trypsin = Albuminoids changed
to peptones in
alkaline solutions.

Disease germ = Toxin: Enzyme = Morbid phenomena.

Disease germ = Contagious disease.

Further consideration of pathogenic microörganisms will be found in connection with contagious diseases.

MEDICAL DIAGNOSIS.

Means of diagnosis. Usual health of the subject. History of the
attack. Objective symptoms, interdependent disease, fever, diseases
that may be confounded, subsidiary disease, diagnostic signs, organ
involved, pathological test injections, course of disease, sporadic or
zymotic, result of treatment.

Diagnosis is the determination of the seat and nature of a given disease and its distinction from other morbid conditions. Its importance to the practitioner cannot be overestimated as it occupies the pivotal position between causes, nature, morbid phenomena, and symptoms on the one hand, and prognosis, prevention, and treatment on the other. Unless the conclusions are sound as to causes, nature, lesions, and symptoms, there can be no certain diagnosis, and without a correct diagnosis, prognosis, prevention, and treatment can have no intelligent or scientific basis. The practitioner who finds a dropsical condition and who is satisfied to pronounce it dropsy and institute treatment is abusing his trust. He must find whether this dropsy results from disease of the kidneys, heart, bloodvessels, lymphatics, liver, lungs, bowels, or the structures in which it is shown; whether it is due to parasites or imperfect sanguification or to other morbid conditions, before he dare prescribe treatment and predict results. So in every other affection; the failure to make a correct diagnosis opens to the practitioner many doors of error, and he is happy indeed if he can escape the injuring of his patient.

In seeking a sound diagnosis we must attend to the following among other indications:

1st. The habitual state of health of the subject. The genus, breed, age, environment, habits, (pet dog, watch dog, hound, sheep-dog, ox, bull, cow, milch cow, sheep in the field or housed, pig in pen or at large, diet, regimen, water, race horse, draught horse, work, exposure, etc.) as well as the personal equation of temperament, idiosyncrasy, heredity, etc., must all be carefully considered.

2d. The history of the present illness as to its apparent cause, mode of invasion, duration and progress.

3d. The objective symptoms by which it is manifested. All that can be ascertained in the way of symptomatology, local and general, the probable existence of interdependent disease, and all actual structural lesions and disorders of function should be thoroughly investigated. As supplementary to the more prominent objective symptoms any fever or other constitutional disorder must be sought for; a mental list must be made of the diseases which resemble this one, and these must be excluded one by one by careful attention to the differential symptoms; other diseases which are probably subsidiary to this, should be similarly investigated and excluded; any really diagnostic sign of the suspected disease must be carefully established and the diagnosis finally placed on a solid foundation. The discovery of a constitutional (febrile) disease to which a distinctive name can be given is by no means the end of the diagnosis; the structural lesions of the disease may be largely localized in an unimportant organ where they may remain circumscribed without compromising life, or they may be seated in a vital organ which will render the disease grave to the last degree or necessarily fatal. For example: Anthrax of a dense, dry part of the skin may be a mild local disease; anthrax of an internal organ is usually fatal. Every local complication therefore, should be as carefully diagnosed as the connected constitutional disorder.

But diagnosis cannot always be certain. In the early stages of certain fevers two forms may be as yet indistinguishable and a day or two may be required to develop differential symptoms. In some occult forms of disease all differential symptoms may fail us. A method of diagnosis which has hitherto been applied only to tuberculosis and glanders is manifestly capable of much wider application, to diseases attended with a febrile reaction. This consists in a hypodermic injection of a minimum dose of the sterilized and filtered products of the culture of the disease germ, which produces no effect on the healthy system but causes febrile reaction or local inflammation, or both, in the diseased. This will be treated more fully under the respective diseases.

In connection with such a method, but above all when no such resort has been had, the obscure case should be seen frequently, the course, duration, and termination of the disease should be noted, also its tendency—sporadic or epizootic, and finally the result of treatment. This last resort may often secure diagnosis and cure at once as when a course of iodine cures an obscure actinomycosis.

SYMPTOMATOLOGY. SEMEIOLOGY.

Definition. Symptom. Sign. Constitutional symptoms—local, objective,
subjective, direct—idiopathic, indirect—symptomatic, premonitory.
Anamnesis. Position. Movements. Decubitus. Acute. Chronic. Fever.
Sthenic. Asthenic. State of limbs, muzzle, nose, snout, palmar-pad,
hoof, bill, digits, mouth. Thermometry. Normal temperature, in doors,
in field, at work, in hot season, in nervous subject, in thirst, in
youth—age, starvation, plethora, cold, sleep, rest, stimulants,
suppressed perspiration, eliminants, antipyretics. Fever temperature,
morning, evening, transient elevation, persistent rise, sudden
fall—collapse, crisis. Fatal elevation. Rise during defervescence.
Pulse. Respiration. Skin, staring coat, pallor, coldness, dryness,
harshness, mellowness, pliancy, hidebound, yolk, clapped wool, scurfy,
lesions, itchiness, tenderness, loss of hair, emphysema, anasarca,
sweat, sebum. Expression, life, dullness, paralysis, dropsy,
jaundiced, eye, discolorations, photophobia, amaurosis, pinched face.
Nasal mucosa, red, violet, etc., nodules, polypi, osseous disease,
pentastoma, œstrus, discharge from teeth—sinuses—actinomycosis—tumors.
State of the bowels, kidneys, nervous system.

The usual basis of diagnosis must be a clear and intelligent observation of the symptoms of disease. A _symptom_ is an appreciable evidence of disease. A _symptom_ however may indicate illness, without affording the means of diagnosis, while the term sign is often used for a pathognomonic symptom—one by which the disease can be identified. Used in this sense a _sign_ may be said to be a diagnostic symptom.

1. =Constitutional Symptoms= are such as affect the entire system, like a rise of body temperature, or a shivering fit.

2. =Local Symptoms= are confined to a definite area as redness, tenderness, swelling, ulceration.

3. =Objective Symptoms= include all that can be recognized by the senses of the observer. These alone are available in dealing with the lower animals.

4. =Subjective Symptoms= can only be felt by the patient himself, as pain, giddiness, cold, heat, blindness, numbness. Such symptoms are therefore only obtainable from the human patient who can tell how he feels. In the lower animals they can only be matter of inference, thus pain may be inferred from lameness or wincing on pressure, and giddiness from unsteady gait. The fact that the veterinarian is restricted to objective symptoms renders his task a specially difficult one, yet this has its compensation, as this very restriction tends to train the observant practitioner to greater skill.

5. =Direct Symptoms= (=idiopathic=) are those which are connected with the seat of disease, as the redness, exudation, and swelling of inflammation.

6. =Indirect= (=sympathetic=, =dependent=) =Symptoms= are observable at a distance from the actual disease:—as when headache attends on dyspepsia, or lameness in the right shoulder upon disease of the liver.

7. =Premonitory= or =precursory symptoms= precede the diagnostic symptoms of some diseases, thus dullness and languor often heralds an approaching fever, and the strangles of young horses is often preceded by a general unthrifty appearance, poor appetite and indisposition to exertion.

In observing symptoms as in other things, some have far greater natural ability than others, but in all a careful training will do much to develop and improve the power and habit. A most important thing in such habits is the strict maintenance of a system, not to be followed as a cast iron rule but to be constantly kept in mind and strictly carried out except when sound judgement and experience show it to be unnecessary.

=Anamnesis.= As a rule the first thing to be learned about a patient is his history, and personal and hereditary characteristics. What are his general health, temperament, previous attacks, hereditary predisposition, environment? Is the site of the building, its condition as regards soil, springs, drainage, structure, ventilation, light, cleanliness such as would favor any particular disorder or class of disorder? Is the patient in high, low, or moderate condition, robust or debilitated, alert and lively or dull and stupid? Have other animals suffered recently, or at a corresponding season, or under similar conditions in apparently the same manner? How long has the patient suffered, were there any premonitory indications of illness, what were the first symptoms, and what symptoms have followed up to the present? Has there been any change of food, water or management that might throw light on the cause? Has there been any change of weather or unwonted exposure to cold, storm, overwork, compulsory abstinence or enforced retention of some secretion? If a female is she pregnant?

Having exhausted this method, using such lines of inquiry as promise good results in the particular case, the veterinarian is prepared to bring his own powers of observation to bear more directly.

=Position= and =movements= will often furnish valuable data. The _horse_ which lies on his ribs, stands obstinately in chest diseases, or whenever there is much interference with breathing. The ruminants and carnivora on the other hand which lie on their smooth or padded sternum, can breath with comfort in this position and only stand up persistently in the worst cases. The habit of standing day and night is also characteristic of anchylosed back or loins in the solipede. Roached back may be natural, or the result of overwork and slight sprains or injuries of the loins, of anchylosis, of intestinal or renal inflammation, or of certain injuries to the limbs. The extension of the head on the neck may suggest sore throat, chest disease, tumors around the throat, abscess (fistula) of the pole, sprain or spasm of the extensors of the neck, disease of the axoido-atloid joint, tetanus, or cervical rheumatism. Dropping of head and neck might suggest paresis, mechanical injury to the levator muscles or cervical ligament, extreme debility, or prostration from a profoundly depressing fever or poisoning. Inability or indisposition to back, might indicate sprain or fracture of the back, anchylosis, laceration of the sublumbar muscles, paresis, cerebral or spinal inflammation, softening or other lesion, tetanus, laminitis, dislocated patella and certain other affections. Swaying or unsteadiness in walking or turning would similarly suggest sprain or fracture of the back, paresis and other nervous and locomotor injuries. The solipede with peritonitis arches the back and draws the hind feet forward under the belly, with impacted colon or obstruction to urination he will often stretch with fore limbs advanced and hind limbs retracted. The mode of decubitus may be significant. With peritonitis, enteritis, metritis or acute nephritis or hepatitis the solipede lies down slowly and with caution: with spasmodic colic he throws himself down as if reckless of possible injury. Lying well up on the costal cartilages and side of the breast bone suggests a slight affection of the air passages; lying on the side, disease of other parts. Rolling on the back may indicate simple intestinal spasm, but also blocking by intussusception, impaction, volvulus or otherwise. Sitting on the haunches may suggest a similar trouble or it may imply ruptured stomach or diaphragm. The dog may sit on his haunches in health, or with dyspnœa in acute affections of the respiratory organs, asthma and heart affections. Decubitus on the belly with hind legs extended backward, may imply paraplegia, or acute inflammation of the abdominal organs. Lying with the nose in the flank or turning the head toward the flank, though a normal position of rest, often indicates abdominal suffering. Turning of the head to one side may, however, suggest injury, spasm or rheumatism of the cervical muscles, or disease on the corresponding side of the brain. Animals, at liberty, lie more frequently on the side on which the heaviest internal organs are lodged, thus ruminants, pigs, and dogs rest on the right (the side of the liver) though in cattle with a heavily loaded rumen the condition may be reversed. Decubitus on the abdomen, with the limbs extended and abducted implies profound nervous disorder or shock.

Habitual decubitus often indicates severe suffering in legs or feet. Resting one limb more than another implies injury to that limb. Standing with the pastern of one limb more upright than the others has the same meaning. Extension of one fore foot in advance of its fellow with flexion of the pastern and fetlock denotes suffering in the posterior part of the foot or in the flexors. Flexion of carpus and fetlock without advance of the foot probably bespeaks injury to shoulder or elbow. Inability to bear weight on the fore limb, without knuckling at the knee, should call for examination of the olecranon and joints especially the elbow. Inability to extend the carpus should lead to investigation of the flexor muscles and tendons, the joints and the heel. Movement of the hind limb without flexure of the tarsus would suggest injury to that joint, the stifle or the flexor metatarsi tendon. Inability to extend stifle and hock, should demand examination of the tendo-Achillus and olecranon, of the triceps extensor cruris and of its nerves.

Atrophy of a muscle or group would require scrutiny of its tendons and its nerve and blood supply.

More precise indications of injury of the locomotor system must be found under surgery.

After posture, the general or constitutional disorder may claim attention. Is the illness acute or chronic? Is fever present? Has the animal had a rigor? Does the coat stare in patches (along the spine) or generally? Is there perspiration? Is there full, clear, somewhat congested eye (=sthenic=) or drooping lids over a dull brownish sclerotic (=asthenic=). Are the lower parts of the limbs and other extremities cold, and the roots of the horns or ears hot? Is there significant heat and dryness of the muzzle (ox), nose (dog), snout (pig), palmar-pad (carnivora), hoof (solidungala, bisulcates), bill and digits (birds)? Has the mouth the hot burning feeling of fever? Finally is the temperature as indicated by the thermometer abnormally high? To estimate this with any degree of certainty one must be well acquainted with the normal temperature.

=Normal temperature.= As taken indoors under ordinary conditions, the normal temperature taken in the rectum may be: fowl, 107°–110°F.; swine, 103°–106°F.; goat and sheep, 103°–104°F.; ox, 100°–102°F.; dog, 99°–100°F.; horse, 99°–99.6°F. Ranging in the fields, at work, or on forcing or stimulating feeding, it may be 1° higher than when at rest indoors. A whole herd may be raised 2° by a three miles drive in warm weather. In our summer heats a rise of 1° is common. In nervous animals any change in management may raise the temperature, for example, 1° to 2° after failure to water at the usual time, or from retaining the milk in the udder when the milker had been changed. Young animals are normally .5° to 1° warmer than old ones though more sensitive to the action of cold. Half starved animals, when put on abundant and nutritious food may have a rise of 1° or more. Females in heat, in advanced pregnancy and at the time of parturition are usually 1° to 3° above the natural temperature. Among the agencies lowering temperature are: cold, (1° to 2°); sleep, (1° to 2°); rest; starvation; alcoholic and other circulatory stimulants which fill the cutaneous capillaries and thereby cool the whole mass of blood; suppression of insensible perspiration (retention of waste matters) as by varnishing the skin which lowers the temperature to 25°; purgatives and diuretics (1°); certain drugs like antipyrin, acetanilid, etc., which act on the heat producing centres and retard metabolic changes.