Secondary pentobarbital poisoning in two dogs: a cautionary tale.

Two dogs, a 13-year-old spayed female and a 7-year-old neutered male, were diagnosed with pentobarbital poisoning. Follow-up investigation determined that the source of pentobarbital was the carcass of a horse that had been euthanized more than 2 years previously and that was also apparently responsible for the death of a least 1, and possibly 2, other dogs. The fact that the horse carcass remained lethally toxic more than 2 years after it was euthanized reemphasizes the necessity of proper disposal of euthanized animals.