1. Department of Clinical Studies, University of Pennsylvania School of Veterinary Medicine, New Bolton Center, 382 West Street Road, Kennett Square, PA 19348, USA.
2. Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-447, USA.
3. Pennsylvania Equine Toxicology & Research Center, West Chester University, 220 E. Rosedale Ave West Chester, PA 19382, USA.