SPECIAL REPORT ON DISEASES OF CATTLE TEXT

_Symptoms._--There is usually a continuous uneasiness or frequent shaking of the head, occasionally the manifestation of exceedingly great pain. The animal may rub the head and ear against trees or other objects in an endeavor to dislodge the offending body. _Treatment._--A careful examination reveals the cause, which may be removed with a pair of forceps or scraped out with a hairpin or piece of wire bent at one end. If much inflammation exists, the ear may be swollen so that the foreign substance is hidden from sight; then a probe may be inserted to feel for the object, which, when found, should be removed, even if it becomes necessary to split the ear at the base. Afterwards treat the ear with frequent warm water fomentations and the injection of soapy water or oil and water. SCURFY EARS. Cattle are subject to scurfy ears, which may be owing to a generally morbid condition of the skin, or may be confined to the ears alone. The affected animal shows an inclination to rub the ear; thick scales, which sometimes have the appearance of hard, dry, horny scales, of scurf collect on it. This condition is chiefly caused by a faulty secretion of the sebaceous glands of the ear. Thoroughly clean the ear with a stiff brush, then anoint it, so far as affected, with vaseline 4 parts to 1 part of white precipitate ointment. If the scurfy ears are only a part of a general scurfiness of the skin, the condition of the animal needs attention. (See "Pityriasis," p. 329.) FROSTBITE. It is not uncommon among young cattle which are poorly nourished and exposed outdoors to storms and extreme cold to suffer frostbite of the ear, which may constitute actual freezing of the part. _Symptoms._--Frostbite presents naturally every degree of severity from the mere chilling of the tip of the ear to positive freezing and death of a portion. In a day or two after the freezing has occurred the ear becomes swollen and very painful; the dead part remains cold and begins to shrivel; a line of separation then forms between the inflamed and the dead or dying portion, and finally the piece destroyed drops off, leaving a raw healing surface. When the ear is only slightly affected by the cold, an excoriation or peeling off of superficial skin takes place, accompanied with some pain and itching. _Treatment._--A good liniment for frozen ears is a mixture of turpentine, ammonia, and chloroform, of each 1 part, added to 6 parts of sweet oil. Rub this on the ear several times a day. It will relieve pain and stimulate the circulation, thus favoring a recovery of the injured structures. LACERATIONS OF THE EAR. Aggressive dogs are the most frequent cause of lacerated ear, generally leaving a torn, ragged edge and bruised cartilage. If the wound is extensive, a trimming of the ragged edges becomes necessary; then the edges should be fastened together with silver wire, catgut, or strong, thick, linen thread, taking a deep hold, and pine tar applied. DISEASE OF THE CARTILAGE AND NECROSIS. Occasionally the cartilages of the ear become affected, usually the result of a deep bruise; pus forms, burrows under the skin, and may find a discharge from any part of the ear more or less distant from the seat of the disease. When the cartilage has been extensively injured, pieces of it may become dead (necrosed) and dissolve, to be carried away with the pus, or it may lead to extensive sloughing and the formation of numerous running sores. In the disease of the cartilage there is seldom much swelling or great pain. The discharge is usually very offensive, and occasionally streaked with blood. Whenever there is a long-continued, persistent discharge from one or more openings in the ear, disease of the cartilage may be suspected. _Treatment._--The sinus formed by the passage of matter should be probed and searched to the bottom for the presence of a foreign substance or the evidence of decaying cartilage. When the probe touches necrosed cartilage it will feel like a piece of dry leather or partially softened wood. A counter opening must then be made at this place, and all diseased cartilage cut away with the knife. The subsequent treatment consists in keeping the artificial wound open for the discharge of pus, and the injection of chlorid of zinc, 5 grains to the ounce of water, once or twice a day, until the wound is healed. ENCHONDROMA OF THE EAR. This is an excessive growth of cartilage, found at the base of the ear in the form of a hard, painless tumor, firmly attached to the movable ear. The only recourse for its removal is the knife in the hands of one acquainted with the anatomy of the part involved in the operation. INFECTIOUS DISEASES OF CATTLE. Revised by JOHN R. MOHLER, A. M., V. M. D., _Chief, Bureau of Animal Industry._ GENERAL INTRODUCTION. The importance, to the farmer and stock raiser, of a general knowledge of the nature of infectious diseases need not be insisted on, as it must be evident to all who have charge of farm animals. The growing facilities for intercourse between one section of a country and another, and between different countries, cause a wide distribution of the infectious diseases once restricted to a definite locality. Not only the animals themselves, but the cars, vessels, or other conveyances in which they are carried may become agents for the dissemination of disease. The growing tendency of specialization in agriculture, which leads to the maintenance of large herds of cattle, sheep, and hogs, makes infectious diseases more common and more dangerous. Fresh animals are being continually introduced which may be the carriers of disease from other herds, and when disease is once brought into a large herd the losses become very high, because it is difficult, if not impossible, to check it after it has once obtained a foothold. These considerations make it plain that only by the most careful supervision by intelligent men who understand the nature of infectious diseases and their causes in a general way can these be kept away. We must likewise consider how incomplete our knowledge concerning many diseases is, and probably will be for some time to come. The suggestions and recommendations offered by investigators, therefore, may not always be correct, and may require frequent modification as our information grows more comprehensive and exact. An infectious disease may be defined as any malady caused by the introduction, into the body, of minute organisms of a vegetable or animal nature which have the power of indefinite multiplication and of setting free certain peculiar poisons which are chiefly responsible for the morbid changes. This definition might include diseases caused by certain animal parasites, such as trichinÊ, for example, which multiply in the digestive tract, but whose progeny is limited to a single generation. By common consent the term "infectious" is restricted to those diseases caused by the invasion and multiplication of certain very minute unicellular organisms included under the general classes of bacteria and protozoa. Nearly all the diseases of cattle for which a definite cause has been traced are from bacteria. Among these are tuberculosis, anthrax, blackleg, and tetanus (or lockjaw). Some diseases, such as Texas fever and nagana, are traceable to protozoa, while others, like actinomycosis and aspergillosis, are caused by fungi. Those diseases of which the cause is unknown or imperfectly worked out are pleuropneumonia, rinderpest, foot-and-mouth disease, rabies, cowpox, malignant catarrh, and dysentery. Bacteria may be defined as very minute, unicellular organisms of a plantlike character. Their form is very simple, as may be seen from an inspection of the various species depicted on Plate XXVIII. The description of these figures will be found on page 360. The magnification there given will furnish the reader some idea of their very minute size. They multiply in two ways. The bacterium elongates and then divides in the middle to form 2 daughter cells. These go through the same process at once, and thus 4 cells are produced. The division of these leads to 8, the division of 8 to 16, and so on indefinitely. The rapidity with which this multiplication takes place depends upon the nature of the bacterium. The bacillus of tuberculosis multiplies very slowly, while that of anthrax does so with great rapidity, provided both are in the most favorable condition. Another mode of reproduction, limited to certain classes of bacteria, consists in the formation of a spore within the body of the bacterium. Spore formation usually takes place when the conditions pertaining to the growth of the bacteria become unfavorable. The spores are much more resistant to destructive agents than the bacteria which produced them. The anthrax spore may live several years in a dried state, but the anthrax bacillus perishes in a few days under like conditions. This matter will be referred to again when we come to discuss the subject of disinfection. Of the protozoa which cause disease very little is at present known. One which produces Texas fever is pictured on Plate XLV, in figs. 4 and 5. These parasites have a more complex life history than bacteria; and as they can not be grown in artificial media, their thorough investigation is at present hampered with great difficulties. The differences in the symptoms and lesions of the various infectious diseases are due to differences in the respective organisms causing them. Similarly the great differences observed in the sources from which animals become infected and the manner in which infection takes place are due to differences in the life history of these minute organisms. Much discussion has taken place of late years concerning the precise meaning of the words "infection" and "contagion." * * * * * VARIOUS BACTERIA WHICH PRODUCE DISEASE IN CATTLE. DESCRIPTION OF PLATE XXVIII. The bacteria on this plate are partly from tissues, partly from cultures, and stained artificially with aniline colors (fuchsin or methylene blue). Figs 6 and 7 are copied from Fr‰nkel and Pfeiffer's atlas. All but fig. 7 are magnified 1,000 times; fig. 7, 500 times. Fig. 1. Bacteria from pneumonia in cattle. These are also the cause of hemorrhagic septicemia and are closely related to swine-plague bacteria. These bacteria were drawn from a piece of spleen pulp (rabbit). Fig. 2. Micrococci (streptococcus) which produce inflammation of the lining membranes of the abdomen, thorax, heart, brain, and joints. Frequently associated with the preceding bacteria in abscesses. Fig. 3. Micrococci (staphylococcus) which produce inflammation and suppuration; also pyemia. Fig. 4. Bacilli of blackleg. The pale oval bodies as well as the light spots in one end of the bacilli represent spores. Fig. 5. Bacilli which produce tetanus or lockjaw. The light spot in the enlarged end of each rod represents a spore. Fig. 6. Bacilli of tuberculosis. Microscopic sections of a pearly nodule from the lining membrane of the chest cavity. The bacilli are stained red and appear as small straight rods within the cells of the nodule or tubercle. Fig. 7. Bacilli of anthrax. Bacilli from the spleen of a mouse inoculated with a culture. The bacilli were obtained from the blood of a cow which died of anthrax in Mississippi. The bacilli appear as rods stained blue. The round bodies are blood corpuscles, also stained artificially. [Illustration: PLATE XXVIII. Haines del. ZEESE-WILKINSON CO., INC., N.Y. VARIOUS BACTERIA WHICH PRODUCE DISEASE IN CATTLE.] * * * * * These words, however, are now wholly inadequate to express the complex processes of infection, and it may be said that each species of bacterium or protozoon has its own peculiar way of invading the animal body, differing more or less from all the rest. There are, however, a few broad distinctions which may be expressed with the help of these old terms. Infection, as laid down above, refers at present in a comprehensive way to all microorganisms capable of setting up disease in the body. Some microorganisms are transmitted directly from one animal to another, and the diseases produced may be called contagious. Among these are included pleuropneumonia, rinderpest, foot-and-mouth disease, rabies, cowpox, and tuberculosis. Again, certain organisms are perhaps never transmitted from one animal to another, but may come from the soil. Among these are tetanus, blackleg, anthrax to a large extent, and perhaps actinomycosis in part. These diseases, according to some authorities, may be called miasmatic. There is a third class of infectious diseases, the specific bacteria of which are transmitted from one animal to another, as with the contagious diseases, but the bacteria may, under certain favorable conditions, find food enough in the soil and in the surroundings of animals to multiply to some extent after they have left the sick animal and before they gain entrance into a healthy one. This general classification is subject to change if we take other characteristics into consideration. Thus tuberculosis, because of its insidious beginning and slow course, would not by many be considered contagious in the sense that foot-and-mouth disease is; yet, in either case, the bacillus must come from preexisting disease. The disease of rabies, or hydrophobia, is not contagious in the sense that rinderpest is, because the virus of rabies must be inoculated into a wound before it can take effect; yet, in both cases, the virus passes without modification from one animal to another, though in different ways. Again, all the diseases under the second group, which seem to come from the soil and from pastures, are in one sense contagious in that the virus may be taken from a sick animal and inoculated directly, with positive results, into a healthy animal. Other illustrations may be cited which show that these old terms are not in themselves satisfactory. There are so many conditions which enter into the process of infection that no single classification will give a sufficiently correct or comprehensive idea of it. These statements will be easily understood if the different infectious diseases in the following pages are studied with reference to the way or ways in which each disease may be contracted. Enough has been said, therefore, to show that if we wish to make ourselves acquainted with the dangers of any given disease, we must study it and not rely upon any single work to tell the whole story. Infectious diseases have, as a general rule, a period of incubation, which comprises the time elapsing between the exposure to the infection and the actual appearance of the disease. This period varies with the malady. The most common symptom of this class of diseases is fever. The severity of the fever is measured by the temperature of the animal; this is readily and accurately ascertainable by the clinical thermometer. (See Pl. III, fig. 1.) The other symptoms are variable and depend upon the particular organ or organs most implicated. Loss of appetite, cessation of rumination and milk secretion, and general dullness are symptoms quite invariably present in most infectious diseases. During the course of infectious diseases secondary diseases or complications may arise which are largely caused by bacteria other than those producing the original malady. These complications are often so severe as to become fatal. In general it may be stated that they are due to filthy surroundings, and hence cleanliness may become an important aid to recovery. The treatment of infectious diseases is given under each malady so far as this is allowable or advisable. These diseases are not, as a rule, amenable to treatment. When the symptoms have once appeared the disease is liable to run its course in spite of treatment, and if it is one from which animals usually recover, all that can be done is to put them into the most favorable surroundings. Many infectious diseases lead sooner or later to death, treatment is useless so far as the sick are concerned, and it may be worse than useless for those not yet infected. All animals suffering with infectious diseases are more or less directly a menace to all others. They represent for the time being manufactories of disease germs, and they are giving them off more or less abundantly during the period of disease. They may infect others directly or they may scatter the virus about, and the surroundings may become a future source of infection for healthy animals. This leads us to the subject of prevention as the most important of all which claim our attention. In this place only a few general remarks will suffice to bring the subject before the reader. The most important thing is to keep disease away from a herd or farm. To do this all sick or suspicious animals should be avoided. A grave form of disease may be introduced by apparently mild or trivial cases brought in from without. It is generally conceded that continual change and movement of animals are the most potent means by which infectious diseases are disseminated. With some cattle diseases, such as anthrax, rinderpest, and pleuropneumonia, preventive inoculation is resorted to in some countries. This may be desirable when certain diseases have become established in any locality so that eradication is impossible. It should not be practiced in territories where a given disease may still be extirpated by ordinary precautions. Preventive inoculation is applicable to only a few maladies, and therefore its aid in the control of diseases is limited. When an infectious disease has gained foothold in a herd the course to be pursued will depend upon the nature of the malady. A good rule is to kill diseased animals, especially when the disease is liable to run a chronic course, as in tuberculosis. The next important step is to separate the well from the sick by placing the former on fresh ground. This is rarely possible; hence the destruction or removal of the sick, with thorough disinfection of the infected locality, is the next thing to be done. As to the disinfectants to be used, special directions are given under the various diseases, to which the reader is referred. Here we will simply call attention briefly to the general subject. DISINFECTION AND DISINFECTANTS. Disinfection consists in the use of certain substances which possess the power to destroy bacteria or their spores, or both. Those which are cheapest and most available for animal diseases are ordinary freshly slaked lime or unslaked in powder, chlorid of lime, crude carbolic acid, corrosive sublimate, formaldehyde gas, formalin, and compound cresol solution. (1) Slaked lime is perhaps the most easily procured, but its disinfecting power is limited. While it is capable of destroying all bacteria in their vegetative state, it is unable to destroy such spores as those of anthrax and blackleg. It is probable, however, that in incrusting spores it may destroy their vitality sooner or later. It is regarded as safe practice to use only spore-destroying substances for the virus of those diseases of which we have no definite knowledge. Nevertheless, in the absence of other disinfectants, lime is very useful. It may be employed as a whitewash on wood and stone and sprinkled as a dilute wash or in powder over yards, manure heaps, and over carcasses before they are buried, and over the ground on which they have lain to prevent other animals from carrying the infection away. (2) Chlorid of lime is more efficient than simple slaked or unslaked lime, as it destroys spores. It is the ordinary bleaching powder of commerce and is quite unstable, hence old preparations, unless sealed, are of little value. A 5 per cent solution is sufficiently strong for all spore-bearing bacteria (3 ounces in 2 quarts of water). It may be efficiently applied to