Suspected dimethoate toxicity in cattle

Dimethoate, an organophosphorus insecticide, was the suspected cause of toxicosis in a group of young cattle grazing on pasture that had been sprayed 6 weeks before the onset of clinical signs. Affected animals had primarily nicotinic signs, such as muscle twitching, stiffness, weakness and paralysis, though muscarinic signs, such as diarrhea, salivation and pollakiuria, were also observed. Whole blood acetylcholinesterase activity was depressed in 3 animals. The atypical clinical syndrome and poor response to treatment with atropine and other anticholinergics may have been due to coexistent hypomagnesemia.