THE SYMPTOMS OF TIIE DISEASE in cat tle are often very difficult to recognize in the early stages. The first noticeable symptom of a chronic case is a dry cough. The condition of the animal slowly deteriorates and there is a loss of flesh, accompanied with an unhealthy appearance of the coat. The disease affects nearly all of the organs and tis sues of the body, but in individual cases may be confined to one organ or a set of neighboring organs. In the internal This substance contains the toxin or poisonous principle of the tubercle ba cillus but none of the living bacilli. It cannot, therefore, cause the disease in living animals. When inoculated into healthy cattle it produces no reaction of any note. In tuberculous cattle, how ever, it causes an elevation of tempera ture of one to three degrees, together with swelling at the point of inocula tion. In making the tuberculin test the temperature of the animal should be taken at intervals of about two hours, for four or five times in order to de termine the average normal temperature of each animal. After inoculation with tuberculin, the temperature is again taken at intervals of two hours or less and if an elevation of two degrees is noted, it may be taken for granted that the animal is tuberculous. The great value of tuberculin, therefore, lies in the fact that it enables us to recognize tuberculosis in animals before any ex ternal symptoms appear.
One of the surprising facts in con nection with tuberculosis is that an ani mal may be affected for a year or two without losing weight and without showing any visible signs of the disease. During this time, however, it may spread tuberculosis throughout the herd.