1. Laboratory of Veterinary Surgery, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan
2. Department of Clinical Studies, Samora Machel School of Veterinary Medicine, University of Zambia, Lusaka 10101, Zambia
3. Veterinary Medical Teaching Hospital, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido 060-0818, Japan