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Cannabis Poisoning Cases in Pets Have Risen Since Legalization, Study Finds

By Alexander Beadle

Published: May 04, 2022   
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The number of cannabis poisoning cases reported in pets has increased significantly since 2018, according to a new study from researchers at the University of Guelph, Ontario.

Published in the journal PLOS One, the study surveyed more than 200 practicing veterinarians in Canada and the United States and examined the frequency of cannabis-related poisoning events in pets, as well as the treatment outcomes of these cases since the legalization of cannabis in Canada in October 2018.

Although the researchers did see a significant increase in cannabis toxicosis cases, the majority of these events were not serious and could be treated as outpatient cases with the pet making a full recovery.

The study also highlighted the need for better diagnostic equipment, as many veterinarians reported using human urine drug test kits to confirm their cannabis toxicosis diagnosis.

Edibles are the most common cause of cannabis-induced toxicosis

Although around 60 percent of vets reported no change in the number of cannabis toxicosis cases they had seen at the individual level, almost all of those vets who did see a change reported significant increases in the number of cannabis toxicosis cases they observed.

These cases were primarily in dogs, but there were also a number of cases reported involving cats, iguanas, ferrets, horses, and cockatoos testing positive in drug tests or matching the clinical signs for cannabis toxicosis.

“Those symptoms basically ranged from urinary incontinence, with the pet peeing everywhere, to ataxia, which is movement-related issues, to hyperesthesia where they’re showing increased sensitivity to all of the senses and any stimulation of those senses,” lead researcher Dr Jibran Khokhar, a professor at the Ontario Veterinary College, told Global News.

The vast majority of the veterinarians surveyed practiced in Canada and there did appear to be a significant overall increase in cannabis-induced toxicosis events following Canada’s legalization of cannabis in October 2018. However, it should be noted that edibles were frequently cited as the most common source of exposure, and edible cannabis products were not legalized until October 2019.

The study authors also noted that the nature of the study meant that it was impossible to tell if the observed increase was purely down to more cannabis toxicosis events taking place, or whether there was an uptick in reporting following the change in legal status. Additionally, cannabis is not approved for veterinary use in Canada, so there is a chance that people might be intentionally giving their pets the drug and simply pretending to their vet that their dog ate an edible.

​​“After seeing an adverse effect, intentional exposure may be reported as accidental,” Khokhar said in a statement. “That’s where the challenge in all of this lies.”

Most cases are non-serious

The majority of these cannabis poisonings were relatively benign, resulting in moderate lethargy, disorientation, and urinary incontinence. Outpatient monitoring was the most common course of treatment given, though some pets were admitted for less than 48 hours to receive intravenous fluids (to prevent dehydration). Activated charcoal was also occasionally administered to halt further absorption of cannabis that was still in the stomach.

Out of the 278 total cases of cannabis toxicosis reported by veterinarians, nearly all made a full recovery within 72 hours. However, there were 16 pet deaths thought to be associated with these cannabis poisonings.

“It’s interesting,” Khokhar said in a statement. “You don’t see cannabis overdose deaths in humans.”

Due to the nature of the survey, the circumstances surrounding each of these deaths is not clear. This means that the researchers cannot rule out underlying medical conditions or other non-cannabis ingredients as contributing factors to these deaths.

Speaking to Global News, Khokhar elaborated, “[pet deaths are] a relatively small proportion and it could be related to other additives like chocolate or xylitol that might have been in the cannabis edible,” Khokhar said. “But if the pets are consuming an edible, you have to be concerned about both the cannabis in it, but then also those other ingredients.”

The University of Guelph scientists believe that more research still needs to be done to clarify the effects of accidental cannabis exposure in pets. More research into creating effective diagnostic kits may also be of use, they explain, as many of the vets surveyed reported using human urine drug test kits to confirm their diagnoses. These test kits may be unreliable for animals such as dogs, as these animals metabolize THC in a different way to humans, and so can return false-negative results.

Currently, there are no established treatment methods for accidental cannabis poisonings. While the majority of cases reported by the vets were not serious, more could be done to develop treatments for those few cases that are of greater concern, say the researchers.

“Our goal is, if we can begin to model it in animals, maybe we can intervene with a drug or an agent that either reverses or blocks the effects of the cannabinoids,” Khokhar said in a statement.

That kind of research could help not just pets with accidental ingestions but also children, he added.


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