AUSTIN (KXAN) — After the Travis County Medical Examiner announced he had detected Xylazine — a horse tranquilizer — for the first time in people who died of overdoses, an Austin emergency room doctor is talking about his experience treating some of those patients.

Dr. Daniel Walk, an emergency physician in Austin and member of the Texas Medical Association committee on emergency services and trauma, said he’s already seeing Xylazine patients in his emergency room with symptoms ranging from extreme drowsiness, in the most mild cases, to cardiac arrest.

“I have seen multiple deaths so far, one from a mass casualty, within the past year. Unfortunately many lives have been cut short by this new drug,” Walk said.

Xylazine is a sedative approved for use in large animals. Though it is not approved for human use, it’s being mixed into other illicit drugs. Walk said it creates a concoction that’s very difficult to treat.

“This can lead to people being crippled or killed. People who are otherwise often young and healthy, who unfortunately choose to use drugs but may not understand the implications, the reactions will then stop breathing and sometimes end up with permanent brain damage so that they are crippled for the rest of their lives,” he explained.

The tranquillizer presents an additional challenge in that it doesn’t respond to naloxone, or Narcan, which reverses only opioid overdoses. Drugs like heroin, fentanyl and morphine do. Health officials are still recommending giving naloxone to people during an overdose because they’re so often mixed.

Walk hopes people take the time to educate themselves on the emerging issue, and talk to those around them who might have an addiction to drugs.

“If you have someone in your family, or friend, who does drugs and may or may not understand this risk, I would encourage them to seek treatment and seek help for their addiction,” Walk said.