Subacute and chronic toxic hepatopathy in cattle grazing pasture with <i>Crotalaria spectabilis</i>

This report describes subacute and chronic toxic hepatopathy in cattle due to <i>Crotalaria spectabilis</i> poisoning. A total of 200 male Nellore cattle were introduced into a paddock contaminated with <i>C. spectabilis</i>. After spending 20 days grazing in this area, 6 cattle became ill and died. The remaining 194 cattle were moved to non-contaminated pasture in a nearby farm and, 45 days after arrival, 15 cattle became ill and died. Three affected cattle were necropsied. The main clinical changes consisted of anorexia, isolation from the herd, weight loss, jaundice, recumbency, and death. The primary lesions were observed in the liver. Subacutely poisoned cattle had slightly firm livers with an accentuated lobular pattern. Histologically, hepatocyte loss with dilated sinusoids, hepatomegalocytosis, and fibrosis was observed. Cattle with chronic disease had small, pale, firm livers with an irregular hepatic capsular surface. Microscopic changes included hepatocyte loss, hepatomegalocytosis, bile duct proliferation, and fibrosis.