A drug testing service in Toronto says it has detected a new, highly potent animal tranquilizer circulating in the city’s unregulated drug supply.

Toronto’s Drug Checking Service (TDCS), a free and anonymous public health service offered at five harm reduction agencies, said in a Jan. 29 alert that it first identified a substance that is either medetomidine or dexmedetomidine late last month.

“Both are used to put either animals or people into deep states of sedation and we are finding this drug or drugs in the unregulated fentanyl supply,” said TDCS manager Hayley Thompson.