Bovine tuberculosis is a chronic infectious disease caused by bovine Mycobacterium tuberculosis, as well as human and avian Mycobacterium tuberculosis. The disease is characterized by the formation of tuberculous nodules in certain organs in the body, followed by caseous necrosis or calcium death in the center of the nodules.

The incubation period is generally 6 to 45 days, and some are longer. According to the different parts of the disease, the disease can be divided into the following three types.

(1) Tuberculosis. It is characterized by long-term and stubborn dry cough, which is most obvious early in the morning. The appetite is normal at first, but the patient becomes tired easily and gradually loses weight. In severe cases, breathing difficulty may be seen.

(2) Breast tuberculosis. Generally, the lymph nodes on the breast are swollen first, and then localized and diffuse induration occurs in both breast areas, which is heatless, painless, and uneven in surface. The amount of lactation decreases, the milk becomes thinner, and in severe cases, the mammary glands atrophy and lactation stops.

(3) Intestinal tuberculosis. It is characterized by alternating occurrence of weight loss and persistent diarrhea, or constipation and diarrhea. The feces is bloody or pus-filled and smells fishy. In addition, Mycobacterium tuberculosis can also invade other organs, so testicular tuberculosis, uterine tuberculosis, serosal tuberculosis and brain tuberculosis can occur.