Marijuana toxicosis in 2 donkeys — Sage Perspectives Blog

By Dr. Alyson Fitzgerald

The prevalence of the marijuana use has increased over the past decade with the changing state-wide legislative landscape in the United States. There are now stores in various states that sell this product for recreational use in humans. This in turn has resulted in more veterinary visits for our canine companions who were exposed to their owner’s marijuana and were negatively affected. This article highlights a new species that is also susceptible to adverse effects from THC exposure and demonstrates important clinical signs for veterinarians to look out for. Two donkeys (an 8-year-old jenny and a 20-year-old jack) from the same farm were hand fed roughly 3-5 grams of mature cannabis buds that were grown for human consumption. The caretakers first noticed adverse effects 24-36 hours after consumption in the jenny and 72 hours after consumption in the jack. Canine marijuana toxicosis, in comparison, usually has an onset of clinical signs within a few hours.

Dogs affected by marijuana toxicosis exhibit clinical signs such as nausea, depressed mentation, urine dribbling, decreased heart rate, dilated pupils and incoordination. The donkeys in this paper experienced depressed mentation, incoordination, head pressing, abdominal discomfort (colic), increased heart rate, increased respiratory rate, decreased rectal temperature, decreased tongue tone and delayed mastication of food. On rectal palpation in the field prior to referral the jenny had a large colon displacement on rectal palpation. Routine bloodwork, abdominal ultrasound, abdominocentesis, fecal flotation and skull radiographs were performed on the jenny and did not reveal any abnormalities. Both donkeys made a full recovery within 48 hours after close monitoring and receiving supportive therapies. Treatment included mineral oil and fluids via a nasogastric tube, anti-spasmodics to help with abdominal discomfort and non-steroidal anti-inflammatories for pain control. There is one report of cannabinoid exposure to both horses and mules in 1951 which resulted in rapid onset of death after ingesting a large amount of Cannabis indica.

We were able to confirm the presence of marijuana by detecting THC and other secondary metabolites (11-OH-THC and THC-acid) in the donkey’s plasma utilizing High Performance Liquid Chromatography (HPLC). This was a collaborative effort using validated analytical methods by both the Cornell University Animal Health Diagnostic Center and the Kansas State Veterinary Diagnostic Lab. Cannabidiol (CBD), which is a non-psychoactive component of marijuana, was not detected in the plasma of either donkey. The jenny had a higher plasma concentration of THC (53.3ng/mL) compared to the jack (35ng/mL). It is challenging to draw conclusions to this discrepancy since the exact amount of cannabis that was ingested was not accurately quantified, the time frame of ingestion to blood draw was different, and the metabolite concentrations were generated by two different analytical methods.

The treatment of marijuana toxicosis in dogs includes decontamination strategies such as intravenous fluids, activated charcoal, inducing emesis if neurologically appropriate and a history of recent exposure, lipid emulsion therapy, and gastric lavage in severe cases. There have not been reports of efficacious decontamination therapies in donkeys with marijuana toxicosis, but we postulated that laxatives, gastric lavage and oral activated charcoal may be helpful to decrease length of hospitalization and speed up recovery time. Given the depressive effects of marijuana, a lower dose of sedative agents should be considered if needing to facilitate additional diagnostic or therapeutic procedures. The jenny in this paper was sedated with intravenous detomidine (8mcg/kg) and butorphanol (8mcg/kg) which resulted in profound ataxia. It may be helpful to send samples to a veterinary diagnostic lab if a clinician is suspicious of exposure and there is not a confirmed history of marijuana exposure.