Ot.i.tIS (INFLAMMATION OF THE INTERNAL EAR).

Inflammation of the deep part of the ear is often difficult to recognize in cattle. It may be caused by disease of bone in that region, from blows inflicted by drivers, or from injury by other cattle. Occasionally the ear becomes involved in actinomycosis (lumpy jaw), or the inflammation may be the result of a tuberculous affection.

_Symptoms._--The animal will hold its head to one side, or shake it, while the ear itself is held immovable. The movement of the jaws in eating usually gives rise to a manifestation of pain; the base of the ear may be feverish and swollen, and very sensitive to the touch. If the inflammation has advanced to a suppurative stage, offensive matter will flow from the ear.

_Treatment._--At first, hot fomentations to reduce pain and fever, followed by a sharp blister below the ear. Laudanum, 1 part to 10 of sweet oil, may be injected into the ear to relieve pain and to soften the secretions. If there is a discharge from the ear, it should be thoroughly washed out by injecting warm soapsuds until all the matter has been washed away; then inject the following mixture twice a day: Sulphate of morphia, 20 grains; water, 1 pint; glycerin, 4 ounces.

ABSCESS.

Abscesses, caused by contusions, sometimes form about the base of the ear, either inside or outside. A serous cyst is found occasionally between the cartilage and the skin on the base of the ear, which may be from a similar cause.

_Treatment._--With the knife make a free incision into the most prominent part of the abscess or cyst, then, with a syringe, wash out the sac with carbolized water. If the abscess recurs, open it again, wash it out, and inject tincture of iodin, or fill it with iodoform.

FUNGOID GROWTHS.

As a result of laceration or wound of any kind, fungous growths, characterized by a raw, bleeding, granulating surface, with a tendency to become pendulous, may develop on the ear.

_Treatment._--The whole tumor or diseased structure should be cut away, and the wound treated daily with a dressing of carbolized cosmoline or turpentine and sweet oil, 1 part of the former to 4 of the latter.

FOREIGN BODIES IN THE EAR.

Bugs have been known to gain entrance into the ears of animals. I once removed an acorn from the ear of a cow that had been roaming in the woods; also pieces of wood from a stanchion may be lodged accidentally in the ear.

_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 sc.r.a.ped 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, h.o.r.n.y 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 const.i.tute 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 tr.i.m.m.i.n.g 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 pa.s.sage 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 trichinae, 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 cla.s.ses 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 teta.n.u.s (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 cla.s.ses 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).