1. Department of Veterinary Science, University of Wyoming, 1174 Snowy Range Road, Laramie, Wyoming, 82070, USA
2. Department of Veterinary Pathology, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602, USA
3. School of Veterinary Medicine, Department of Population Health and Reproduction, University of California, Davis, California 95616, USA
4. Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin 53706-1102, USA