Intoxication of dairy cows in Uruguay by ingestion of cocklebur () seeds in sorghum silage.

The ingestion of cotyledons or seeds of cocklebur () causes poisoning as a result of acute liver failure. Here we describe a spontaneous outbreak of toxicity in dairy cows in Uruguay. The outbreak occurred in the winter when the cows were fed sorghum silage contaminated with seeds. Clinical signs of depression, anorexia, paddling, opisthotonos, muscle tremors, sternal recumbency, and death were observed 2-12 h following ingestion. Of 160 Holstein cows, 30 (19%) animals were ill, and 6 (4%) died. At autopsy, the liver had a diffuse mottled appearance with intercalated red and yellow areas. Histologically, centrilobular hemorrhagic coagulative necrosis was found. The diagnosis of this natural outbreak of intoxication was based on the clinical signs observed, finding the fruits of in the silage, and the characteristic macroscopic and histologic lesions.