1. Second Department of Veterinary internal Medicine, College of Agriculture and Veterinary Medicine, Nihon University 3-34-1 Shimouma, Setagaya-ku, Tokyo 152, Japan
2. Department of Veterinary Obstetrics and Gynecology, College of Agriculture and Veterinary Medicine, Nihon University 1866, Kameino, Fujisawa, Kanagawa 252, Japan
3. Department of legal medicine, Teikyo University, School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173, Japan