Differential sensitivity to the delayed neurotoxin tri‐o‐tolyl phosphate in several avian species

Publisher Website
Google Scholar
Abstract
Adult White Leghorn chickens, ring-necked pheasants, mallards, bobwhites and Japanese quail were administered single oral doses of tri-o-tolyl phosphate (TOTP) at 125, 250, 500 and 1000 mg/kg body wt. Corn oil served as the vehicle control. At 24 h after dosing, half the birds from each group were killed for determination of whole-brain neurotoxic esterase (NTE) activity. The remaining birds were maintained for 21 days. Daily observations for the development of clinical signs typical of delayed neurotoxicity were begun 7 days after dosing and continued for the subsequent 14 days. In the Japanese quail and bobwhite, all doses of TOTP resulted in NTE inhibition > 70%, yet no birds of either species developed ataxia or paralysis. In the mallard, of TOTP caused inhibition of NTE activity > 61% or resulted in the development of clinical signs. In the pheasant, all doses of TOTP caused at least a 70% inhibition of whole-brain NTE activity, yet only birds receiving 500 and 1000 mg/kg developed clinical signs. In the chicken, all TOTP doses caused inhibition of NTE > 80%, and all doses resulted in clinical signs typical of delayed neurotoxicity.