Tuberculosis in farmed rheas (Rhea americana).

Avian tuberculosis was diagnosed in two mature rheas on different ratite farms over a 2-year period. Both birds had died after progressively losing body condition. Caseonecrotic granulomas were scattered throughout the liver and spleen in both birds. Similar granulomas were in the lung of one bird and bilaterally in the subcutis cranial to the shoulder in the other bird. Smears of several granulomas from both rheas revealed large numbers of acid-fast bacilli. Histologically, the granulomas had caseonecrotic, non-mineralized centers surrounded by giant cells. Large numbers of acid-fast bacilli were seen free in the necrotic material and within inflammatory cells. Amyloidosis of the liver and spleen occurred in one rhea. Mycobacterium avium complex was isolated at a reference laboratory from hepatic granulomas submitted from one rhea.