1. Departments of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616
2. Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, CA 95616
3. Department of Clinical Research and Veterinary Public Health, University of Bern, 3001 Bern, Switzerland
4. Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, Minneapolis, MN 55455