While data shows the number of overdose deaths is falling in Canada, there’s a growing concern over the detection of an animal tranquilizer being found in the unregulated drug supply.
It’s called medetomidine and is a potent sedative used primarily by veterinarians.
A recent alert by the B.C. Centre for Disease Control says opioids like fentanyl are now being often mixed with the sedative.
But it’s not only showing up in British Columbia.
“Medetomidine itself is used by veterinarians and we don’t have approval to be using that in humans and we’ve started to see that it is showing up in the unregulated drug supply,” said Dr. Emily Austin, the medical director of the Ontario Poison Centre.
According to Toronto’s Drug Check Services, the number of illicit drugs that medetomidine is showing up in could be at about 80 per cent, even higher than the 50 per cent B.C. public health officials say they’re seeing.
The side effects associated with the drug vary.
“Medetomidine has been associated with hallucinations and dropping blood pressure, and very low or slow pulses,” said Dr. Karen McDonald with Toronto’s Drug Check Services. “We first detected it in the fentanyl samples that we were checking here in Toronto in December of 2023.”
The service saw a recent spike in veterinary tranquilizers in fentanyl samples in recent months. Where numbers previously sat mostly before 20 per cent prior to October 2023, it jumped to almost 40 per cent by April 2024 and sat at 86 per cent of expected fentanyl samples last month.
Before medetomidine, another animal tranquilizer known as xylanizine was being cut into fentanyl. The drug, which was also known as “Tranq” or “Zombie Drug,” was known for causing large open sores in users.
Dr. Mark Lysyshyn, deputy public health officer at Vancouver Coastal Health, said the numbers between the two drugs are a stark comparison.
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“Xylazine never, we never got to contaminating more than maybe five per cent of opioids in B.C. at the most,” he said. “But you know, medetomidine right now is contaminating 30, 40, 50 per cent of opioids.”
He told Global News the adding of sedatives and tranqulizers to opioids is part of a growing trend that has dated back to about 2019, when benzodiazepines were being added.
“I assume it’s being added because it sort of increases the effect of the opioids,” Lysyshyn suggested.
That’s led to what he called a “surge” of overdose events, including 911 calls and visits to the emergency room.
At the same time, Lysyshyn noted despite the increase in ER visits, the rate of overdose deaths in B.C. continues to decline.
“Although it’s causing major problems for people who use drugs and major problems for the health-care system right now, it’s not increasing the risk of death,” he added.
According to the federal government’s Health Infobase, the rate of apparent opioid toxicity deaths from January to June 2025 was 13.5 deaths for every 100,000 Canadians. That’s compared to the peak of 20 for every 100,000 at the opioid crisis’ peak in 2023.
Even though the rate of deaths may not be increasing, non-fatal overdoses are.
In Toronto, Paramedic Services attended 350 non-fatal and 12 fatal calls for suspected opioid overdoses. The number was higher compared to the monthly average of 229 non-fatal calls attended in 2025, and the 238 in January of that year. In terms of fatal overdoses, there were also 12 in 2025 but 18 in 2024.
The data by the Toronto Overdose Information System does not note how many suspected overdose cases involved veterinary tranquilizers, but McDonald said those drugs create a higher danger.
“Certainly the combination of drugs like medetomidine and xylazine in combination with fentanyl do increase risks for people who are using those drugs,” she said. “The problem is these veterinary tranquilizers don’t respond to naloxone because they aren’t an opioid.
“They’re certainly making the situation worse.”
In its recent alert, the BCCDC urged people to call 911 immediately if they witness a suspected overdose, stressing that drug poisonings are medical emergencies.
Though officials say the tranquilizers are making it a difficult situation, they advise naloxone should still be used during an overdose even when non-opioid substances are involved.
“The effect that naloxone will have when somebody has used something that includes fentanyl and medetomidine and xylazine is a bit more complicated, but it will restore that person’s ability to breathe if you give the right dose,” said Austin.
—with files from Global News’ Touria Izri
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