Tuberculosis-like granulomas in cattle caused by Actinomycetes.

From 280 lesions from normal cattle at slaughter, 10 were found to contain thin, branching, Gram-positive organisms belonging to the Nocardia/Streptomyces group and this was confirmed by culture in 3 cases. Macroscopically the older lesions were similar in appearance to those of tuberculosis. Microscopically, all lesions contained numerous foreign body giant cells and thin, branching organisms. The older lesions also contained areas of necrosis, caseation, mineralisation and fibrosis.