1. Division of Pathology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa 210-9501, Japan
2. Pathogenetic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu 501-1193, Japan
3. Department of Animal Nursing, Yamazaki Gakuen University, 4-7-2 Minamiosawa, Hachioji-shi, Tokyo 192-0364, Japan