1. McPhail Equine Performance Center, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
2. Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
3. Department of Anatomy, Physiology and Biochemistry (AFB), Faculty of Veterinary Medicine and Animal Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
4. Equine Science Center, Department of Animal Science, Rutgers, the State University of New Jersey, 84 Lipman Drive, New Brunswick, NJ 08901, USA