Thickened intestinal mucosa due to Johne's disease
The last portion of the small intestine, or ileum, shown in the upper part of the photo is thickened due to the inflammatory response caused by an M. paratuberculosis infection. Normally the intestine is thin and pliable as seen in the lower half of the photo. Such intestinal thickening is less pronounced in species other than cattle. This photo was kindly provided to me by the late B.J. Jørgensen who worked at the State Veterinary Serum Laboratory in Copenhagen, Denmark.