Dogs will eat anything, won’t they?
Cat Barr, PhD, DABT
Four dogs were brought to a veterinary clinic when one had been seizing for several hours and the other three had begun to tremble. All four dogs had reportedly been running loose in a rural area. Vomiting was induced in the worst of the tremblers, and all three of them responded to overnight pentobarbital/fluid therapy and were released the next day. The seizing animal did not respond well and was euthanized. Bloodwork from the worst dog showed no elevations in blood urea nitrogen or creatinine, ruling out ethylene glycol antifreeze as a potential etiology. Liver enzymes were close enough to normal to rule out a hepatotoxicity. In the absence of elevated indicators in the clinical chemistry panel, presence of neurological signs pointed to a direct neurotoxin that caused seizures.
Stomach content was submitted to the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) in College Station for testing. Because no visible evidence of strychnine (gopher bait, green milo) was observed, the sample was forwarded to another laboratory for a convulsant screen including strychnine, penitrem A and roquefortine C. The latter two compounds are tremorgenic mycotoxins – neurotoxins produced by molds, particularly Penicillium sp. Penitrem A is the more toxic of the two by about 10-fold, affecting both the central and the peripheral nervous systems to produce tremors, convulsions, ataxia and nystagmus. Onset is usually rapid (within about an hour of ingestion), but elimination tends to take longer than that of strychnine. Humans and mice are similarly affected by the toxin and the response is dose-dependent.
This particular stomach content sample was sent out for referral testing at the Pennsylvania Animal Diagnostic Laboratory System at New Bolton Center. The sample was found to contain 11.8 ppm penitrem A and 76.0 ppm roquefortine C. Neither of these compounds are normally detected in canine stomach content at currently detectable levels (method detection limit 0.010 ppm).
In Texas, we tend to see more penitrem A poisoning in cooler weather and the source has been reported on several occasions to be compost piles – as was likely the source of exposure in this case. The leader of the dog pack beat the others to the smelliest, moldiest morsels, and it was his downfall.
For more information about this case, contact Dr. Cat Barr, TVMDL toxicologist, at 1.888.646.5623. To learn more about TVMDL’s test offerings, visit tvmdl.tamu.edu or call one of our four laboratories.
References
Walter SL, 2002: Acute penitrem A and roquefortine poisoning in a dog. Can Vet J 45(5):372-374.
Young KL, Villar D, Carson TL, et al., 2003: Tremorgenic mycotoxin intoxication with penitrem A and roquefortine in two dogs. J Am Vet Med Assoc 222(1):52-53, 35.