An outbreak of Johne’s disease in a herd of finishing calves in Fars province of Iran

During a 2-month period (Jan to Feb 2005), eight of 7–9-month-old male crossbred finishing calves were presented with diarrhea and emaciation. They had good appetite and normal vital signs. Ziehl–Neelsen staining smears of the feces and gut wall of these animals were positive for the presence of clumps of small acid-fast bacilli. Fecal samples were decontaminated and cultured for the isolation of Mycobacterium paratuberculosis. After fecal culture, M. paratuberculosis colonies were isolated. These cases did not respond to the initial treatments and were slaughtered. Gross postmortem findings were a thickened, corrugated ileum and enlarged edematous mesenteric lymph nodes as well as the granulomatous lesions in the liver. Histopathologically, there was an extensive lymphocytic infiltration of the ileal lamina propria. A catarrhal focal necrotic enteritis associated with a granulomatous lymphadenitis was observed.