Scientists probe cannabis’ potential as anti-vomiting therapy for pets

A research team headed by Dr. Al Chicoine, a board-certified veterinary pharmacologist and assistant professor at the Western College of Veterinary Medicine (WCVM), aims to find out whether cannabis can be used to prevent a trying health issue in some dogs and cats: chronic vomiting.

If cannabis products can safely be used in pets to treat vomiting, they could be a useful tool for animal practitioners. While vomiting is associated with many chronic diseases of companion animals, there are no drugs approved for long-term treatment of vomiting in dogs or cats — veterinarians are limited to only a couple of options.

Using cannabis to treat vomiting isn’t new. Medical researchers have been interested in tetrahydrocannabinol (THC), the major psychoactive compound in marijuana that provides its “high,” for many years.

Many human and animal studies have focused on the ability of THC and analogous compounds to help prevent vomiting, and when other treatments fail, some physicians recommend that their human cancer patients take whole marijuana or synthetic THC to help treat vomiting and nausea caused by chemotherapy drugs.

Based on recent research in rodents and some preliminary trials in human patients, scientists are hopeful that a non-psychoactive chemical in cannabis, cannabidiol (CBD), could exert similar effects.

“Cannabis is a very complex plant with many different phytochemicals (biologically active compounds) associated with it, and we’re not really sure which specific component is exerting these effects or if they’re kind of working together as a team,” says Chicoine. “We still have to tease all of that apart.”

The studies planned by Chicoine’s group will use a medical grade cannabis oil — similar to formulations used by consumers interested in a CBD-THC oil with very low risk of a “high.” In this experimental model, the researchers plan to administer several doses of CBD oil or a placebo to healthy cats with no medical history of chronic vomiting. Afterwards, they will give the cats dexmedetomidine — the same drug that veterinarians use to induce vomiting in cats after toxin exposure – then measure if and how much they vomit.

“Then we wait a couple of weeks, give the cats a break and let them get any of the CBD out of their system, and then we switch them up and allocate them to another group,” says Chicoine. He adds that this process allows team members to evaluate how individual cats react to the CBD treatment versus the placebo therapy.

The team will also test how cats absorb CBD and THC in their blood and process the drugs in their bodies. Researchers plan to use a similar testing protocol for dogs participating in the study.

“In terms of medical use of cannabis in [pets], we have very, very limited published information,” says Chicoine.

This study aims to start filling in some of those gaps. These investigations will also provide basic information about the safety of using CBD oil in pets, like “any side effects owners [who use CBD] maybe aren’t reporting, things like sedation … or any neurological changes,” he says.

Dr. Kevin Cosford, a specialist in small animal internal medicine at the WCVM, is leading the same basic study in dogs.

These preliminary studies could provide part of the justification that researchers would need to perform a more complicated study with client volunteers interested in using CBD oil to treat vomiting in their own pets. Clinical trials like these are one step required before Health Canada will approve CBD oil for veterinary use.  

“We need to show that the drug is safe, and the drug is effective. But this requires very well-designed, controlled clinical trials,” says Chicoine, adding that he doesn’t expect any significant health risks to the animals participating in this study.

So far, Canadian veterinarians can’t legally recommend or prescribe any cannabis products for pets, although they can discuss current research and how to reduce the risk of adverse effects with owners. If the results of this study are positive, does that mean pet owners will soon be able to pick up a prescription for CBD oil from their local veterinary clinic?

Not quite, says Chicoine.

“[If the results are positive,] we’d still need further studies to really fine tune the dose regimen and the types of anti-vomiting uses for CBD oil in [pets],” he says. “This study alone is not going to provide all the answers, but it’s a good starting point.”

Kate Illing of Rocky View County, Alta., is a second-year veterinary student at the WCVM. Her story is part of a series of articles written by WCVM summer research students.

This article was recently featured in Vet Topics, the official publication of the WCVM's Companion Animal Health Fund. Find the Fall 2019 issue at cahfpets.ca.