Whole blood cholinesterase activity in calves after topical treatment with famphur.

Holstein-Friesian calves (n = 12) were treated with famphur at three dosage levels 20.25 mg/kg, 40.5 mg/kg and 60.75 mg/kg. The only changes observed in the calves were pupillary constriction in two calves receiving the high dosage and marked depression of whole blood acetylcholinestrase activity. The length of time the blood acetylcholinesterase activity was reduced was longer than previously reported in Hereford cattle.