Fatal Amanita muscaria poisoning in a dog confirmed by PCR identification of mushrooms

Diagnosing mushroom poisoning in dogs can be difficult and often includes identification of suspect mushrooms. Visual identification may be hindered by mastication, oral medications, or poor quality of environmental mushroom samples. Other analytical techniques may thus be necessary to aid in mushroom identification. A 5-y-old neutered male Labrador Retriever dog developed acute onset of vomiting, diarrhea, tremors, seizures, and somnolence. The dog was treated at a veterinary clinic and was briefly stabilized, but died during transport to an emergency clinic. On postmortem examination at the University of Kentucky Veterinary Diagnostic Laboratory, the dog’s stomach was full of mushrooms covered with activated charcoal. Mushrooms were damaged, fragmented, and discolored, precluding accurate visual identification. Mushroom pieces were sent to the Department of Plant Pathology at the University of California–Davis for PCR identification; the neurotoxic mushroom Amanita muscaria was identified. A qualitative liquid chromatography–mass spectrometry (LC-MS) method was developed to detect ibotenic acid and muscimol, the toxic compounds present in A. muscaria. Mushrooms, stomach contents, and urine were analyzed by LC-MS; ibotenic acid and muscimol were detected in all samples. Because identification of ingested mushrooms is sometimes necessary to confirm mushroom poisoning, PCR can identify ingested mushrooms when visual identification is unreliable.