1. Veterinary Teaching Hospital, Faculty of Veterinary Medicine, Hokkaido University, Hokkaido 060-0818, Japan
2. Laboratory of Veterinary Internal Medicine, Department of Clinical Sciences, Faculty of Veterinary Medicine, Hokkaido University, Hokkaido 060-0818, Japan
3. Laboratory of Veterinary Surgery, Department of Clinical Sciences, Faculty of Veterinary Medicine, Hokkaido University, Hokkaido 060-0818, Japan