1. Department of Population Health and Reproduction; School of Veterinary Medicine; University of California-Davis; Davis CA 95616 USA
2. Veterinary Genetics Laboratory; School of Veterinary Medicine; University of California-Davis; Davis CA 95616 USA
3. Department of Veterinary Medicine and Epidemiology; School of Veterinary Medicine; University of California-Davis; Davis CA 95616 USA
4. Department of Large Animal Clinical Sciences; College of Veterinary Medicine; Michigan State University; East Lansing MI 48824 USA
5. Department of Veterinary Population Medicine; College of Veterinary Medicine; University of Minnesota; St. Paul MN 55108 USA