1. Department of Pathobiology, Scott-Ritchey Research Center, College of Veterinary Medicine, Auburn University, Auburn, Alabama, USA.
2. Mid-Atlantic Equine Medical Center, Ringoes, New Jersey, USA.
3. Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA.
4. Duke Clinical Research Institute (DCRI), Durham, North Carolina, USA.