1. Department of Pathobiology, Ontario Veterinary College, University of Guelph, 50 Stone Road E, Guelph, Ontario N1G 2W1, Canada
2. Department of Population Medicine, Ontario Veterinary College, University of Guelph, 50 Stone Road E, Ontario N1G 2W1, Canada
3. Animal Health Laboratory, University of Guelph, 419 Gordon St., Ontario N1G 2W1, Canada