Massive liver hemorrhage in Ontario broiler chickens

A massive liver hemorrhage (MLH) recognized in Ontario broiler chickens had a characteristic clinical course and pathological lesions. Affected flocks had a higher death rate than normal, with no obvious clinical signs. Deaths from MLH began at two weeks of age; the mortality rate returned to a normal level by four weeks. The main necropsy finding was massive multiple liver hemorrhage with consequent profuse hemoperitoneum.