1. Laboratories of Veterinary Surgery and Comparative Pathology, Department of Veterinary Clinical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Nishi 9‐chome, Kita 18‐jo, Kita‐ku, Sapporo 060‐0818, Japan
2. Sapporo General Pathology Laboratory, Nishi 18‐chome, Minami 12‐jo, Chuo‐ku, Sapporo 064‐0912, Japan