Paratuberculosis in different breeds of sheep: A retrospective study of cases

Spontaneous ovine paratuberculosis in an organized farm was diagnosed based on histopathological lesions, demonstration of acid-fast bacilli in different visceral organs, and detection of antibody levels against Mycobacterium paratuberculosis by agar gel immunodiffusion test (AGID). Out of 190 morbid specimens examined histopathologically, 77% of specimens had pathological lesions, which included predominant epithelioid cell formation, infiltration of lymphocytes, monocytes and macrophages. In acid-fast staining of tissue sections, 74% of intestinal specimens and 53% of mesenteric lymph nodes were positive for the presence of acid-fast bacilli. Hematologically, the animals were showing leucopenia, macrocytic and normochromic anemia. Out of 49 animals tested, 28.5% of animals were positive for antibodies against M. paratuberculosis. Local breeds, namely Nilagiri and Sandyno sheep, were found to be more susceptible than exotic breeds, namely Dorset. Females were more susceptible than males. Mortality was noticed in the age group of 4 months to 10 years.