Intestinal Tyzzer's disease and spirochetosis in a guinea pig

Tyzzer's disease (bacillus piliformis infection) was diagnosed in a young guinea pig killed because of diarrhea and poor condition. There was necrosis and inflammation of the colon, cecum and ileum. Typical B. piliformis were in intestinal epithelial cells. Spirochetes were in large numbers in intestinal crypts and were often adjacent to the intracellular B. piliformis. Extracellular B. piliformis occasionally were surrounded by spirochetes.