Thomas E. Wilkinson2Veterinary Teaching Hospital, Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99163. 1Health Sciences Centre, Ontario Veterinary College, University of Guelph, Guelph, ON NIG 2WI, Canada. 2Veterinary Teaching Hospital, Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99163.