1. Department of Veterinary Medicine, Faculty of Agriculture, Iwate University, 3–18–8, Ueda, Morioka, Iwate 020–8550, Japan
2. Department of Surgery, School of Veterinary Medicine, Azabu University, 1–17–71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252–5201, Japan
3. Veterinary Medical Center,Osaka Prefecture University, 1–1, Gakuen-cho, Nakaku, Osaka 599–8531, Japan