1. Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA,
2. Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, University of Utrecht, 3584 CM Urecht, the Netherlands,
3. Department of Companion Animal and Special Species Medicine, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA