U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version



Ecotoxicology and Environmental Safety 73 (2010) 1159–1164; doi:10.1016/j.ecoenv.2010.05.021


The anticoagulant rodenticide diphacinone was slightly toxic (acuteoralLD50 2014 mg/kg) to Northern bobwhite (Colinus virginianus) in a 14-day acute toxicity trial. Precise and sensitive assays of blood clotting (prothrombin time, Russell’s Viper venom time, and thrombin clotting time) were adapted for use in quail, and this combination of assays is recommended to measure the effects of anticoagulant rodenticides. A single oral sub lethal dose of diphacinone (434mg/kg body weight) prolonged clotting time at 48 h post-dose compared to controls. At 783 mg/kg (approximate LD02), clotting time was prolonged at both 24 and 48 h post-dose. Prolongation of in vitro clotting time reflects impaired coagulation complex activity, and was detected before overt signs of toxicity were apparent at the greatest dosages (2868 and 3666mg/kg) in the acute toxicity trial. These clotting time assays and toxicity data will assist in the development of a pharmacodynamics model to predict toxicity, and also facilitate rodenticide hazard and risk assessments in avian species.

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