Officials say horse tranquilizer is showing up in increasing number among people who use illegal drugs in central Pennsylvania. The number of xylazine ulcers, which are gross infections, sores and wounds, are the result of that kind of drug use and doctors are seeing those increasing, too. Xylazine, also referred to as “tranq,” or “tranq dope” and “zombie drug,” is approved for animal use, but not in humans. Investigators say it’s being added to the supply of what used to be mostly heroin, and which now consists largely of fentanyl, which is a man-made opioid.