Pathology of Gastrointestinal Tuberculosis in Cattle.

We describe the pathology of gastrointestinal tuberculosis in three cows. Gross lesions were found in the jejunum and ileum in all cases, and were characterized by button-shaped ulcers in the mucosa overlying Peyer's patches and adjacent mucosa. One case had similar changes in the pyloric region of the abomasum. In the affected intestinal segments, marked granulomatous inflammation effaced the lymphoid follicles of Peyer's patches and often extended transmurally. Transmural granulomatous inflammation was also found in the abomasum of one cow. Acid-fast bacilli were identified by the Ziehl-Neelsen method and the lesions were immunolabelled by an anti-Mycobacterium tuberculosis complex antibody. M. tuberculosis var. bovis was isolated in one case. Disseminated tuberculosis and marked lung lesions in all cows suggested that the gastrointestinal lesions were most likely secondary to pulmonary infection.