The legalization of cannabis has led to an increase in toxicosis in pets, a link University of Guelph researchers determined in new research published today in PLOS ONE.

Canada had one of the highest rates of cannabis use in the world before legalization in 2018, said lead researcher Dr. Jibran Khokhar, professor in the Department of Biomedical Sciences at the Ontario Veterinary College.

Since legalization, he said, the uptick is not necessarily the result of humans increasing their use of cannabis but could reflect more reporting to veterinarians when animals are exposed.

Researchers surveyed more than 200 North American veterinarians (191 of them Canadian) who self-reported over a span of three months in 2021.

They found dogs were the animal most often ingesting cannabis.

Most pet owners did not know where their animals encountered it, according to the data, although some vets reported exposure from discarded joints, human feces, cannabis-infused butter or oil, and compost.

The research was featured in several publications, including the Wall Street Journal, CNN, NBC News and Popular Science .

Edibles most common culprit for cannabis-induced toxicosis

Cats, iguanas, ferrets, horses and cockatoos were all reported to have experienced cannabis toxicosis, based on clinical signs, history of cannabis exposure and urine tests.

Effects included urinary incontinence, disorientation, ataxia (abnormal or uncoordinated movements), lethargy, hyperesthesia (increased sensitivity of the senses) and bradycardia (slowed heart rate).

How often the animals exhibited any of those conditions was measured on a scale from “very often” to “rare,” with most effects occurring “very often.”

Edibles were found to be the most common cause of toxicosis, with animals ingesting cannabis while unattended. Edibles take effect with a slow onset followed by “a long tail afterward,” Khokhar said, adding different breeds and sizes of dogs will have different experiences.

“Even in humans, there’s all sorts of factors that impact how long the drug acts,” he said, including how cannabis is ingested.

While most of the animals had a complete recovery, suggesting no long-term effects, Khokhar noted there were some deaths reported. “It’s interesting,” he said. “You don’t see cannabis overdose deaths in humans.”

He said edibles contain other ingredients such as chocolate, which is poisonous for dogs given their inability to metabolize it, so the deaths could be attributed to various factors.

Research to help find treatment to reverse, block effects of accidental cannabis ingestion

Another problem is that even though cannabis is not legally approved for veterinary use in Canada, people do give it to their dogs, Khokhar said. “After seeing an adverse effect, intentional exposure may be reported as accidental. That’s where the challenge in all of this lies.”

Currently, no treatment exists for cannabis-induced toxicosis in animals; the study reported the animals were monitored and, in a few cases, hospitalized for 24 hours at most.

“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.

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

This research was funded by a Natural Sciences and Engineering Research Council Alliance grant and a Mitacs Accelerate Fellowship in partnership with Avicanna Inc.

Contact:

Dr. Jibran Khokhar
jkhokhar@uoguelph.ca