title: Acute oral median lethal dose of haloxon and coumaphos in sheep as influenced by plasma A esterase.
abstract: Determination of the acute oral medial lethal dose (LD50) of haloxon for lambs classified as to the presence or absence of plasma esterases (A esterase; EsA) rapidly hydrolyzing haloxon revealed markedly different values for the 2 phenotypes of sheep. The LD50 for EsA- lambs was 763 mg/kg of body weight with 95% confidence limits of 543 to 1,072 mg/kg. The acute oral LD50 for EsA+ lambs remains undetermined but was demonstrated to be in excess of 11,392 mg/kg. The acute oral LD50 for a closely related organophosphate (coumaphos) was not different in the 2 phenotypes of sheep.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage*; D003372:Coumaphos / Q000633:toxicity*; D004950:Esterases / Q000097:blood*; D007306:Insecticides / Q000633:toxicity*; D007928:Lethal Dose 50; D009943:Organophosphorus Compounds / Q000633:toxicity*; D012756:Sheep / Q000097:blood*; D012757:Sheep Diseases / Q000139:chemically induced*; D014468:Umbelliferones / Q000633:toxicity*
chemical_list: D000871:Anthelmintics; D007306:Insecticides; D009943:Organophosphorus Compounds; D014468:Umbelliferones; D004950:Esterases; D003372:Coumaphos; C007902:haloxon