Veterinary sedative complicates overdose response, strains emergency departments

A veterinary sedative is increasingly contaminating street fentanyl, creating new challenges for overdose response in Canadian emergency rooms. The drug, called medetomidine, is a synthetic sedative approved only for animal surgery. Its presence in the illicit opioid supply, first detected in 2023, has grown significantly in British Columbia, Ontario and several other provinces. The additive is used to extend the shorter-lasting high of fentanyl, but its effects on humans are not well studied.

Dr. Monty Ghosh, an addictions physician in Calgary, said the drug causes extreme drowsiness alongside dangerously low blood pressure and heart rate. "These are the things that we kind of have to match that we didn't have to match before," Ghosh said. "It's sort of skewed our management strategies for these individuals." The reduced blood flow can lead to serious organ complications. Ghosh and other physicians also report a new, rapid-onset withdrawal syndrome linked to medetomidine that can cause severe hypertension, vomiting and agitated delirium.

This withdrawal can precipitate heart attacks or strokes, according to Ghosh. Nurses at supervised consumption sites in Montreal and B.C. have observed users with very low heart rates remaining unresponsive for hours. Because the sedative effects are delayed compared to other adulterants, continuous monitoring of vital signs is now more critical. Naloxone does not reverse medetomidine's effects, so responders must focus on supporting a patient's breathing during an overdose.

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Treating this withdrawal syndrome is placing a strain on hospital resources. Dr. Sahil Gupta, an emergency physician in Toronto, said these patients often require hospitalization or intensive care to monitor their breathing and consciousness for extended periods. "In our emergency departments, [these] patients take a longer amount of time, both from a nursing, staff physician and time within the hospitals' perspective," Gupta said. In severe cases, patients may need to be placed on a ventilator. Gupta warned that the increased demand for high-level care worsens emergency room overcrowding and wait times. "[Resource] strains like this tend to actually create a lot of disruption and cause increased wait times, overcrowding," he said. He argued that broader social issues must be addressed to see progress. "Unless the whole continuum of homelessness and socioeconomic factors are addressed, 'we're really not going to make inroads,'" Gupta said.

Some hospitals are attempting to address the root causes of repeat visits. In Edmonton, the Bridge Healing program offers immediate housing and support to homeless individuals who come to the emergency department. Dr. Louis Hugo Francescutti, who helps run the program, said staff ask patients if they are homeless and wish to get their life back on track. Those who agree are provided free accommodation and linked to medical services. "Emergency department staff are becoming morally distressed," Francescutti said. "They're burning out because they see a problem that is solvable if we had the right people intervening."

Other doctors point to the closure of supervised consumption sites as a missing part of the solution. Dr. Raghu Venugopal, an emergency physician in Toronto, said these sites allow workers to stabilize overdose patients without sending them into full withdrawal, potentially keeping them out of the ER. "This really matters because if you want safe subways, if you want safe parks, if you want a better-functioning ER, there is a place for people who need to use drugs," he said. A 2026 report found that without such sites, more people end up in emergency departments.

With files from CBC News