1. Department of Population Medicine and Diagnostic Sciences Cornell College of Veterinary MedicineCornell University Ithaca NY USA
2. Department of Veterinary Microbiology and Pathology Washington State University Pullman WA USA
3. Department of Clinical Sciences Cornell College of Veterinary MedicineCornell University Ithaca NY USA
4. Rood & Riddle Equine Hospital Lexington KY USA