Effect of neurotoxic organophosphorus compounds in turkeys.

To determine the neurotoxic effects of organophosphorus compounds in turkeys, adult birds were given a single oral dose of 125, 250, 500 mg/kg triorthotolyl phosphate (TOTP) or a single subcutaneous dose of 0.4 mg/kg O,O'-diisopropyl phosphorofluoridate (DFP). At 24 h after dosing with TOTP, neurotoxic esterase activity was found to be inhibited in a dose-related manner, as were the activities of blood cholinesterase and liver cholinesterase. Clinical signs of neuropathy appeared within 2 wk in TOTP-treated groups of birds with neurotoxic esterase activities at 59 +/- 3% (125 mg/kg), 47 +/- 7% (250 mg/kg) and 33 +/- 3% (500 mg/kg) of control values (mean +/- SEM, n = 5) at 24 h after dosing. Signs appeared earlier in turkeys given DFP. Histological examination revealed only mild lesions of delayed neurotoxicity in birds given either TOTP or DFP.