Tyzzer's disease in Syrian hamsters.

Tyzzer's disease was diagnosed in 18 Syrian hamsters. The clinical signs included sudden onset of diarrhea, dehydration, and lethargy; all affected hamsters died within 48 hours. Gross lesions consisted of multiple white nodules in the heart; dilated cecum and colon containing semiliquid feces, sometimes bearing necrotic plaques on the mucosa; and occasionally, a few small scattered white spots in the liver. Microscopic study of those lesions revealed areas of necrosis and mixed cellular inflammation. The causative agent, Bacillus piliformis, was demonstrated within myocardial fibers, hepatocytes, and colonic epithelial cells. Inoculation of chicken embryos and a clinically normal hamster with a homogenate of cecal wall prepared from affected hamsters resulted in reproduction of the agent and transmission of the disease.