Proceedings of the Vertebrate Pest Conference

A laboratory study was conducted in which tissues from zinc phosphide-killed black-tailed prairie dogs (Cynomys ludovicianus) were fed to domestic ferrets (Mustela putorius). Prairie dogs were fed a 2.03% zinc phosphide bait and upon death, two tissue complexes were prepared: stomach, liver, and intestines, and the remaining carcass. Five male and five female ferrets were each fed one of the two treated tissue complexes. A similar number of ferrets were each fed one of the two control tissue complexes. No poisoning symptoms or emesis were observed and no ferret mortality occurred. Zinc phosphide residue was determined in 10 prairie dog carcasses; 99.9% was found in the stomachs and small intestines. Residues were also detected in the large intestine, caeca, kidneys, and gall bladder/liver, none were found in the lungs, heart, or muscle. The low amounts of zinc phosphide remaining in the carcasses, the absence of ferret mortality, poisoning symptoms or emesis, despite the emetic properties of zinc phosphide, confirm that the risk of secondary poisoning from zinc phosphide is unlikely.