1. School of Veterinary Medicine, University of Pennsylvania, New Bolton Center Campus, 382 West Street Road, Kennett Square, Pennsylvania 19348, United States, Pennsylvania Equine Toxicology and Research Center, West Chester University, West Chester, Pennsylvania 19382, United States, and Equine Drug Testing and Research Program, College of Veterinary Medicine, Cornell University, 925 Warren Drive, Ithaca, New York 14850, United States