Hemorrhagic diathesis, mesenteric hematoma, and colic associated with ingestion of sweet vernal grass in a cow.

A 4-year-old Holstein cow from a farm where 2 cows had recently died suddenly was referred for evaluation of acute severe colic. Right flank laparotomy revealed a large mesenteric hematoma. Within 14 layer chromatographic analyses of the moldy hay and blood from the necropsied cow and the hospitalized cow were positive for dicumarol. A diagnosis of sweet vernal poisoning was confirmed on the basis of clinical and toxicologic findings. The cow was treated with supportive therapy, blood transfusions, and vitamin K1 and recovered without complications. Because sweet vernal grass is becoming common in certain areas and the use of round bales is commonplace, practitioners should be aware of the potential for this toxicosis.