Histopathology
This is a low power magnification photomicrograph of an ileal tissue taken from a cow with Johne's disease (H&E stain). The ileum is thickened by infiltration with macrophages and lymphocytes. This diffuse transmural granulomatous type inflammation is characteristic of Johne's disease in cattle. The degree of inflammatory response is usually much less pronounced in sheep and goats with Johne's disease. With the H&E stain, M. paratuberculosis bacteria can not be seen. (See the "acid-fast stained tissue" photograph for an example of bacteria in ileal tissue.)