HARRISBURG, Pa. (AP) — Pennsylvania Gov. Josh Shapiro will sign legislation to criminalize the misuse of a powerful animal tranquilizer called xylazine that is showing up in supplies of illicit drugs and contributing to a growing number of human overdose deaths, his office said Wednesday.

Xylazine, which is being mixed into fentanyl and other illicit opioids, will remain legal for its intended use by veterinarians.

The bill received approval from the state House of Representatives and the Senate in the past week.

Under the bill, xylazine will be listed as a “schedule III” drug under Pennsylvania’s controlled substance law, formalizing an order that Shapiro issued last year when Pennsylvania joined a growing list of states that were moving to restrict access to xylazine.

Xylazine is a prescription sedative used by veterinarians to safely handle and treat farm animals, wildlife, zoo animals and household pets such as cats and dogs.

Officials say the pain-relieving, muscle-relaxing drug, sometimes referred to as “tranq,” is often abused by being added to fentanyl and heroin. It was detected in 3,000 U.S. drug deaths in 2021, according to the federal Drug Enforcement Administration.

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The illicit use of schedule III drugs carries a penalty of imprisonment of up to five years. The law would require that the drug be stored safely when used professionally, to prevent theft or improper access.

Federal officials last year declared xylazine-laced fentanyl an “emerging threat” and introduced a plan to scale up testing, treatment and efforts to intercept illegal shipments of xylazine.

Xylazine can cause breathing and heart rates to fall to dangerous levels when used in humans. When injected it can cause large open sores and infections, sometimes leading to amputation.