Diagnosis of Johne's disease in cattle using mesenteric lymph node biopsy: accuracy in clinical suspects.

Histopathological examination of biopsies of mesenteric lymph node obtained from the region of the terminal ileum proved to be a very accurate method of diagnosing Johne's disease in the living animal. Identical conclusions were reached in 100 clinical suspects following examination of either mesenteric lymph nodes alone, or a wider range of routine specimens including ileum, caecum, colon and ileocaecal lymph nodes. A method of obtaining biopsy specimens from mesenteric lymph nodes is described and is recommended when an early definitive diagnosis is required.