Foot-and-mouth disease is an acute contact infectious disease of cloven-hoofed animals such as cattle, sheep, pigs and camels. The pathogen of this disease is foot-and-mouth disease virus. The average incubation period of foot-and-mouth disease in cattle is 2 ~ 4 days, the shortest is 1 day, and the longest is about 1 week. The main feature of sick cattle is oral mucosal blisters. When the initial body temperature reaches 40 ~ 4 1℃, the patient is listless and drooling. 1 ~ 2 days later, blisters (the size of broad bean walnut) appeared on the inner surface of lips. At this time, the oral spat was all white foam, which often hung all over the mouth. At the same time or later, blisters appeared on the soft skin between the toes and the hoof crown.

When dairy cows are sick, the symptoms of blisters are not obvious, and they often show symptoms of acute gastroenteritis and myocarditis and suddenly die. The disease generally takes a benign course, and the general oral disease can heal itself within one week. If the hoof is sick, the disease period can be extended to 2 ~ 3 weeks or longer, and the mortality rate is very low, generally not exceeding 1% ~ 2%. At the time of autopsy, the myocardial slices were gray-white or yellowish needle-like spots with stripes like tiger spots, so they were called "tiger spot heart".