1. Laboratory of Small Animal Surgery, Department of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan
2. Veterinary Teaching Hospital, Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku N18 W9, Sapporo, Hokkaido 060-0818, Japan
3. Ogawa Canine Feline Hospital, 1-9-14 Tsunishi, Kamakura 248-0034, Japan