1. From the Department of Large Animal Clinical Sciences (Harding, Baker, Parker),
2. Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; the Prairie Diagnostic Services, Saskatoon, Saskatchewan, Canada (Tumber);
3. the Department of Veterinary Microbiology (McIntosh, Hill, Ellis),
4. the Department of Veterinary Pathology (Middleton),
5. the Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH (Krakowka).