A six-year-old saddle horse with cardinal clinical signs, such as edema of the lower part of the limbs, languishment, and occasional diarrhea, was studied pathologically. A diagnosis of equine miliary tuberculosis, which had rarely been reported in Japan, was made in it. There were notably distinct gross changes on the serous membranes of the thoracic and abdominal cavities. The changes consisted of the multiple to scattered occurrence of both miliary nodules 1 to 3 mm in diameter and fibrous villi of varying shape. The multiple occurrence of miliary nodules of the same kind was also seen in the lung. Lymph nodes were swollen almost all over the body, especially the anterior mesenteric lymph node. Histopathological examination revealed that the nodules were composed of obvious productive granulomatous tuberculous lesions (tubercle formation). The fibrous villi sometimes included specific tuberculous lesions. The lymph nodes were affected with pronounced granulomatous tuberculosis. Acid-fast bacilli, supposedly tubercle bacilli, were only occasionally stained out within tuberculous lesions in the lung, liver, and anterior mesenteric lymph nodes. The site of primary infection was obscure in the present case. In terms of the generalization of the tuberculous lesions, it was speculated that dissemination through the body of the causal organism might possibly have occurred by means of lymphogenous spread.
