Animal tranquilizer found in drug cocktail that caused cluster of overdoses in Belleville, Ont.

A man draws an unknown illicit substance into a syringe before injecting it into his arm as people gather for a rally and march to call on the government to provide a safe supply of illicit drugs in Vancouver, on Wednesday, April 14, 2021. THE CANADIAN PRESS/Darryl Dyck

A potent cocktail of street drugs, including an opioid and two central nervous system depressants, is to blame for almost two dozen overdoses that caused the city of Belleville to declare a state of emergency late last week, says the region’s health unit.

Late Thursday afternoon, Hastings Prince Edward Public Health (HPEPH) told CP24.com that Health Canada's Drug Analysis Service and Cannabis Laboratories found that the most recent drug sample collected by police around the time of last week’s spike in drug poisonings in the community included the “presence of an opioid, a benzodiazepine and xylazine.”

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The most concerning substance in that mix is xylazine, which is also known as “tranq” or “tranq dope” and can cause those who consume it to have difficulty moving, shallow or stopping breathing, low blood pressure, and slower heart rate, especially when consumed with opioids or benzodiazepines.

“Combining xylazine with opioids or central nervous system depressants like benzodiazepines or alcohol can significantly depress these vital functions, increasing the risk of overdose and death,” HPEPH said in a statement.

The regular use of xylazine has also been linked to open skin ulcers or abscesses that can be painful and prone to infection, said the Toronto-based Centre on Drug Policy Evaluation (CDPE), which also operates a community-based drug-checking service. Death is also a real possibility.

Xylazine was first detected in Toronto’s unregulated drug supply in October 2019 and is currently only approved for use on animals. It is most commonly used by vets on horses, deer, dogs, and cats for sedation, muscle relaxation, and pain relief.

The effects of xylazine, as well as benzodiazepines, which are also known as “benzos,” cannot be reversed by using naloxone, Hastings Prince Edward Public Health noted, adding that this challenge can “impact the success of the overdose response, which reinforces the need to call 911.”

That was the case in Belleville on Feb. 8 when emergency responders in the municipality of roughly 55,000 residents became overwhelmed following a surge of calls for suspected drug overdoses in the downtown core. The city said that at one point, emergency personnel saw nine overdose patients in one call that day. In the end, no deaths were reported.

• READ MORE: Belleville, Ont., set to declare state of emergency due to spike in drug overdoses

Earlier this week, Ontario Premier Doug Ford said that he’d help Belleville by providing funding to address the impacts of the overdose crisis on that city.

Ford said he’d be sitting down with Belleville Mayor Neil Ellis to talk about longer-term solutions, including building a community health hub for addictions, mental health and homelessness that will be operated by a consortium of community groups on a larger property donated by the city.

Belleville is seeking an additional $2 million from the province to complete that project, which is known as “The Bridge,” as well as funding to open a detox centre.

Health Canada said that it is also in communication with the City of Belleville about working with the province to address this crisis.

Last November, emergency responders in Belleville were called to 90 suspected overdoses in the span of a week, one of which was fatal, prompting city officials to declare a “community crisis.”

With files from The Canadian Press.