1. Department of Surgical and Radiological Sciences, School of Veterinary Medicine; University of California-Davis; Davis California
2. Department of Small Animal Clinical Sciences; University of Florida; Gainesville Florida
3. Department of Clinical Studies; Ontario Veterinary College, University of Guelph; Guelph Ontario Canada
4. Department of Medicine and Epidemiology, School of Veterinary Medicine; University of California-Davis; Davis California