Disseminated Mycobacterium paratuberculosis infection in a cow.

A cow with chronic diarrhea and weight loss caused by localization of Mycobacterium paratuberculosis in the intestinal tract (Johne's disease) had gross and microscopic changes indicative of a disseminated infection. A direct association between the remote lesions and the intestinal infection was shown by isolation of M paratuberculosis from renal tissue, detection of intracellular M paratuberculosis antigen(s), using an indirect immunoperoxidase method, and by the characteristic granulomatous nature of the lesions. This case illustrates the potential for extra-intestinal lesions in M paratuberculosis infection of cattle and should cause veterinarians to consider mycobacterial disease when confronted with multinodular lesions of the bovine kidney. The immunoperoxidase method was useful in determining the cause of the inflammatory lesion in which intact organisms were not evident.