Cannabis legalization in Canada has not led to an increase in dogs being hospitalized for exposure to THC, according to recent study performed in Canada. A cannabis overdose for dogs can be dangerous when it includes THC, whereas CBD is often touted as having some benefits.
Published as a special report In the Canadian Veterinary Journal, the report examined data from the 12 months prior to legalization in October 2018, and compared it to the 12 months following legalization.
“There was no significant difference in the total number of dogs presenting with signs of THC toxicity in a 12-month period following cannabis legalization compared with the number in a 12-month period before the legislation,” the report stated, adding that “there was also no evidence of a correlation between the legality of cannabis and whether or not presented toxicities were classified as ‘confirmed’ or ‘suspected.’”
The study cites the November 2019 National Cannabis Survey (NCS), which found that the number of Canadians using recreational cannabis had increased from 4.5 million before legalization to 5.1 million, a total of 1.9% of the Canadian population. (The NCS study did not say if it surveyed dogs.)
The report, entitled “Comparing the Prevalence of Tetrahydrocannabinol (THC) Toxicities in Dogs Before and After Legalization of Cannabis in Canada,” examined the canine intakes at the VCA Canada Calgary Animal Referral and Emergency Centre. It found that in the 12 months pre legalization, the hospital reported 39 cases of cannabis toxicity and in the 12 months after legalization, 35.
Puppies are more susceptible
The study found that puppies — dogs under 1 year old — were disproportionately represented in the toxicities, representing one-third of all cases post legalization. The study posits that this is because puppies are “more likely than adult dogs to explore their surroundings by taste, leaving them vulnerable to accidental consumption of the leaves of the Cannabis sativa plant.”
The report cites research that holds that ingestion of cannabis edibles accounts for 66% of marijuana exposures reported to the Pet Poison Hotline in Canada. During the period of time tested, cannabis edibles were not yet legal in Canada.
The study was not able to determine any correlations between the owner’s age or the breed of dog.
The analytics of both pre-legalization and post-legalization hospitalizations included both confirmed and suspected cannabis ingestion cases. In many cases where the owner did not actually see the dog ingest cannabis, the prognosis was made by observing the symptoms of the canine.
It’s not easy to test dogs for marijuana
Testing for THC ingestion in dogs is unreliable because gas chromatography and mass spectrometry may take several days and human urine drug tests can be stifled by the large number of metabolites in canine urine.
Diagnoses are complicated by the fact that symptoms like nervous symptom depression, lethargy and vomiting, can be similar to those of dogs who have ingested ethanol-containing substances like alcohol, while ataxia and cardiac arrhythmias can occur as a result of both chocolate or THC toxicity. The report adds that one of the distinguishing features of THC toxicity is urinary incontinence.
Cannabis ingestion can be highly dangerous for dogs. It can cause depression, vomiting, and tremors, and if a dog ingests a high dose of THC they can suffer a range of reactions including nystagmus, agitation, tachypnea, tachycardia, ataxia, hyperexcitability, and seizures.
Dogs may receive benzodiazepines to calm them down in severe cases, though for the most part treatment involves supporting the dog until it passes out of their system.
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