1. Department of Clinical Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido 080-8555, Japan
2. Department of Veterinary Medicine, Azabu University, Kanagawa 252-5201, Japan
3. NOSAI Hidaka, Hokkaido 059-3105, Japan
4. Hidaka Monbetsu Horse Clinic, Hokkaido 055-0003, Japan