Morphological diagnosis of Johne’s disease: a case report in cattle

The present case report deals with the morphological (gross and histopathological) and histochemical characterization of Johne?s disease in a cow. The carcass was presented in a hidebound condition with sunken eyes and with a history of persistent and nonresponsive diarrhea. Necropsy revealed generalized gelatinization of the visceral and peripheral fat. Thorough gross examination unveiled major pathological changes in the digestive tract. The gallbladder was distended, with severely thickened walls and blood mixed with bile. The small intestine was severely congested and the mesenteric lymph nodes were enlarged. The opening of the small intestine showed marked thickening of the intestinal walls, with a corrugated appearance. Diffuse granulomatous lesions were observed in the mesenteric lymph nodes. Histopathological examination revealed severe infiltration of intestinal layers and mesenteric lymph nodes by macrophages, lymphocytes, and epithelioid cells with multiple Langhans giant cells. Ziehl=Neelsen staining demonstrated multiple acid-fast bacilli in the cytoplasm of macrophages from impression smears.