A tranquiliser used by vets is infiltrating street drugs and deepening addiction across cities in the US. The drug called xylazine is causing wounds so severe that without treatment results in amputation. The problem is particularly bad in Philadelphia – which has long been ground zero for the opioid crisis. On this edition of the Sky News Daily Niall Paterson talks to US Correspondent, Mark Stone who has been to the city and to Professor Paul Cristo from John Hopkins University about the on going opioid crisis in the US. Podcast producers: Rosie Gillott and Emma-Rae Woodhouse Interviews Producer: Alex Edden Junior podcast producer: Charlie Bell Editor Philly Beaumont