Neurotoxicity of triorthotolyl phosphate in chickens of different genotypes in the presence and absence of deoxycorticosterone.

Indices of acute and delayed toxicity following administration of triorthotolyl phosphate (TOTP) were measured in roosters from lines of chickens originating from the Cornell randombred population. Matings were designed to produce individuals that had presence or absence of allele 21 of the B blood system. Non-B21 individuals had allele 13 or 31. Acute inhibition of esterases (neurotoxic esterase, liver cholinesterase, plasma cholinesterases, and plasma carboxylesterases) occurred in all birds within 24 hr of a single oral dose of 360 mg/kg TOTP. Clinical signs of delayed neuropathy were evident within 12 days of TOTP administration, with no significant difference between genotypes. Dietary deoxycorticosterone (40 to 200 ppm) appeared incapable of statistically significant modification of the strong effects of TOTP. Activities of blood esterases were different between roosters having B21/B21 and those with B13 and/or B31.