1. Department of Veterinary Diagnostic Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108
2. The Department of Veterinary Science, South Dakota State University, Brookings, SD 57007
3. Department of Clinical and Population Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108
4. Boehringer Ingelheim Animal Health, Inc., St. Joseph, MO 64502
5. Veterinary Research Laboratories, Stormont, Belfast, Northern Ireland, UK BT4 3SD