1. Shikoku Cytopathological Laboratory, 712 Rokujyo, Takamatsu, Kagawa 761–0303, Japan
2. Shikoku Veterinary Medical Center, 3308–5 Ikenobe, Miki, Kita-gun, Kagawa 761–0701, Japan
3. Department of Veterinary Pathology, Graduate School of Agricultural and Life Science, The University of Tokyo, 1–1–1 Yayoi, Bunkyo-ku, Tokyo 113–8657, Japan