Kan cannabis kanker bij honden behandelen?november 5, 2019
Marion Chorney knew something was wrong with her 11-year-old coonhound Red when she spotted drops of his blood in the snow after he relieved himself last year.
The Burlington woman took him to the vet, but test after test wasn’t revealing the issue. Then, the diagnosis came: bladder cancer.
Vets started Red, who has yet to lose his energy or any weight, on radiation, but plenty of Chorney’s friends with elderly dogs had a treatment of their own to suggest — cannabis.
“They keep asking me why he is not on it,” Chorney said. “I know that it is still in the research stage for dogs. I am so careful with anything I give him and I don’t want to give him anything if it is not really proven.”
That uncertainty around the efficacy of cannabis in treating dogs with bladder cancer is why Samuel Hocker, an assistant professor of veterinary medical oncology at the University of Guelph, has embarked on a three-year study examining the efficacy of the substance for treating urothelial carcinoma tumours in dogs.
Such tumours account for about 2 per cent of the tumours seen in dogs and are often treated with radiation or chemotherapy because they are “extremely difficult” to remove surgically, said Hocker.
His study — partly funded by specialty pet health company Grey Wolf Animal Health and believed to be among the first in Canada to use cannabis to explore animal cancers — is part of a recent boom in interest around what the substance can do for dogs. The interest, experts say, was likely triggered by the legalization of recreational cannabis in Canada last year.
“There’s quite a bit of craze and I don’t know if it will die down,” said Hocker. “Owners are seeing it in human medicine where it has been better researched and seeing it as a way to treat animals holistically without some other side effects.”
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Already researchers in Israel, Australia and the U.S. have looked at whether cannabidiol (CBD) — the non-intoxicating compound found in cannabis and hemp — is effective in treating osteoarthritis in pets and a small study from Colorado State University found that 89 per cent of dogs who received CBD in a clinical trial had a reduction in the frequency of epilepsy-related seizures.
Hocker’s study focuses on three different cell lines from canine bladder tumours. The cell lines will have CBD applied to them to look at whether CBD will kill the cells alone and whether it works better or worse with chemotherapy and/or radiation.
“The goal of my particular studies is to just evaluate whether cannabis kills cancer cells and if so, by what mechanisms is it doing that,” Hocker said. “So can we treat these dogs with bladder cancer with traditional chemotherapy or radiation therapy in conjunction with CBD and will it change the overall survival or will it extend that survival for this type of cancer dogs have?”
This kind of research is important, said Hocker, because vets are anecdotally hearing about more cases of animal cancer, but it’s hard to know if there’s been an uptick in the disease or just an increase in the reporting and diagnosing of it.
Treating bladder cancer can be tricky too because current Canadian laws prevent vets from prescribing the substance to animals. Veterinarians have been lobbying the federal government to allow medical cannabis to be used on animals.
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Their push comes as licensed cannabis producers — still consumed with supplying the substance to retail stores and wading into the newly-legal edibles market — want to cater to pets, too. Smiths Falls, Ont.-based licensed producer Canopy Growth, for example, has teamed up with lifestyle maven Martha Stewart to create a line of CBD products, some of which will be geared toward pets.
“Certainly the single, largest driving force is the demand from pet families,” Dr. Sarah Silcox, the president of the Canadian Association of Veterinary Cannabinoid Medicine, told the Star in an email.
Statistics Canada found in 2017 that about 7.5 million Canadian households had a pet. About 5.9 million Canadians owned dogs and 7.9 million had cats, the government agency found.
That year, Statistics Canada said, Canadian households spent $8.23 billion in total on pets, their food, related services and veterinary care, up from the $6 billion spent on the same items in 2013.
Silcox, a veterinarian who focuses on palliative and hospice care, sees a “tremendous” number of inquiries about the use of cannabis for treating pets diagnosed with cancer and said there is proof of how cannabis and its various components work in animals from thousands of studies.
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“What we don’t have however, is a substantial amount of published studies showing the effects of cannabis on treating common conditions in the animal species that we have as companion animals — namely dogs, cats and horses,” she said.
Cannabis’ legal history, its varying quality and expenses have made research tough, but Silcox believes analyzing the substance further is necessary.
“We are only beginning to scratch the surface into understanding how cannabis works, which products work best for which conditions, how individual or species differences play a role in responses, and which doses are most effective for a given medical condition,” she said.
“There are years, if not decades, of research ahead of us.”