1. Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, P.O. Box 647010, Pullman, WA 99164-7010, USA
2. Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, P.O. Box 647040, Pullman, WA 99164-7040, USA
3. Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, 625 Harrison Street, West Lafayette, IN 47907-2026, USA