Cocklebur poisoning in cattle.

Cocklebur poisoning occurred in a herd of cattle in Oklahoma during the month of July. The poisonous dicotyledonary stage of cocklebur plant growth usually occurs during the early spring in Oklahoma. In this instance, dicotyledonary sprouts were in a lowland pasture adjacent to a river. Sprouting and growth occurred after receding water and hot dry weather had created favorable conditions for germination. The diagnosis was made on the basis of the finding of the dicotyledonary stage of plant growth and evidence of the plants having been grazed, as well as the clinical signs, gross necropsy findings, and histopathologic findings in the affected cattle.