JOhne's Disease.—A chronic specific enteritis of cattle, caused by the growth in the intestinal mucous membrane and mesenteric glands of a bacillus discovered by Jane. It produces thickening of the bowel and interferes with food absorption ; there is diarrhoea and extreme wasting. The course is long, sometimes years, and in such cases the animals are "carriers." Infection is by food contaminated with infected excreta. Early diagnosis is difficult. Suspected animals should be slaughtered ; no treatment is effectual in severe cases. Some animals improve, put on weight, and again relapse. Isolation is important.
Cowpox (variola vaccinia), is a mild, contagious, eruptive dis ease of the udder and teats ; the eruption at its height, when not altered by attempts at milking, shows a depressed centre, a raised silvery edge, containing lymph, and outside this a pink areola. It is transmissible to man, and affords protection against small pox. (See VACCINATION.) In cows it requires little treatment.
Sheep-pox (variola ovine) is the most serious of all the variola of animals. It is highly infectious, and benign and malignant forms are met with. It occurs in France and southern and eastern European countries, but not in America or Australia. It is unlikely to appear in Great Britain. The virus is ultra visible, and very resistant.
Foot-rot, a specific infectious disease of the feet in sheep, is said to be caused by the bacillus of necrosis, but this is probably a secondary invader. It is a soil disease, rare in hilly or light lands, but common on deep soils. Lameness may be severe, tissue changes marked, and the hoofs deformed. Arsenical footbaths are useful for mass treatment. Infected animals should not be introduced to sound flocks.
Tuberculosis.—An inoculable and infectious disease caused by the bacillus of Koch, of which there are three types, human, bovine and avian. No domestic animal is completely immune, but cattle, pigs and poultry are chiefly affected. In cattle, grape-like masses form in the chest and abdominal cavity, the lymphatic glands become enlarged and caseous, and diseased centres appear in the substance of the organs. The symptoms vary greatly ac cording to the organs attacked. Cattle in apparent health may on post-mortem show extensive invasion. The tuberculin test is efficient in proving the existence of infection, but not its degree, and emaciated, heavily-affected animals may fail to react. Con
genital tuberculosis is rare, post-natal infection being the rule. This 'fact induced Bang to advocate isolation of reactors, with pasteurization of milk, for eliminating tuberculosis from herds. Calmette has introduced a live vaccine (B.C.G.) so modified that although it confers immunity from natural infection it is not pathogenic for animals or men. "Open tuberculosis" is a term applied to advanced cases of the disease affecting the lungs, bowels, womb, and udder, or otherwise discharging bacilli and therefore dangerous, and by the Tuberculosis Order all such cases must be notified. In pigs the glands of the throat and the bones are often diseased, and in the latter case the meat is condemned. The bovine bacillus, found in meat and particularly in milk, is the cause of considerable disease, especially in children.
Bacillary White Diarrhoea is the most important disease of fowls in this country, and responsible for more losses than all other diseases combined. It runs an acute course in chicks and a chronic course in adults. Chicks which survive an outbreak may become "carriers," and on reaching maturity produce eggs containing the causal agent, B. pullorum. The disease is mainly introduced by infected eggs, day-old chicks, or adult "carrier" fowls. "Carriers" can be detected by the agglutination test.
Coccidiosis, next in importance, is caused by the protozoan Eimeria avium, and attacks chicks from two to eight weeks old. The mortality varies from 20 to 90%, depending on their age.
Fowl Pox, a contagious disease due to a filter-passing virus, is characterized by eruptive lesions on the skin or its appendages, by diphtheritic membranes in the mouth, or by an oculo-nasal dis charge. There may be present only one of these lesions, or a combination of them, in the same bird.
Fowl Typhoid, enzootic in Wales and the bordering counties, and the cause of heavy annual losses, is a contagious septicaemia, the symptoms being pallidity of comb and a characteristic green ish yellow diarrhoea. The incubation period is about six days and death may occur within 16 days.