An Unusual Case of Relay Pentobarbital Toxicosis in a Dog

Sodium pentobarbital and phenytoin are common constituents of veterinary euthanasia solutions in the United States. Relay, or secondary, barbiturate toxicosis has been reported in carnivorous animals that have fed from the carcasses of euthanized livestock. This case report presents barbiturate toxicosis in a dog. A 2-year-old female spayed Australian shepherd presented comatose 2 h after ingesting an unknown substance on the beach. The material was retrieved from the stomach by gastric lavage and visually identified as fish or other animal tissue. The dog recovered with symptomatic and supportive therapy and was released on the third day of hospitalization. Tissue found on the beach near where the dog walked and a urine sample from the dog were analyzed by gas chromatography/mass spectrometry. Both samples were positive for pentobarbital and phenytoin. The tissue was consistent with mammalian blubber based on gross and histological examination. Three weeks previously, a juvenile humpback whale had stranded on the beach where the dog had ingested the unknown substance. The whale had been euthanized with a barbiturate solution, necropsied, and removed from the beach. It was not definitively determined that the pentobarbital-containing blubber ingested by the dog was from the euthanized whale, but that was the most likely source. Although attempts were made to remove the whale’s remains from the beach, practical considerations made complete removal challenging, if not impossible.