Toxicologic evaluation of O-ethyl O- (p-nitrophenyl) phenylphosphonothioate in cattle and sheep
Palmer, J.S.
Journal of the American Veterinary Medical Association 164(9): 936-938
1974
ISSN/ISBN: 0003-1488 PMID: 4824781 Document Number: 71875
Minimal oral toxic dosages of the pesticide EPN were 2.5 mg/kg body weight in calves and 25 mg/kg for sheep and yearling cattle. Maximal safe dosages were 1 mg/kg in calves and 10 mg/kg for sheep and yearling cattle. At all toxic dosages, cholinesterase (ChE) activities was depressed. At maximal safe dosages, all animals were free of clinical signs, but ChE activities in individual calves and sheep were depressed. For calves and yearling cattle, but less so for sheep, there was great variation within groups as to degree of intoxication induced. Signs were seen in affected sheep between 4 and 7 h, in calves approximately 24 h, and in yearling cattle between 1 and 23 h.