1. Department of Clinical Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080–8555, Japan
2. Maetani Animal Hospital, Taihei, Kita-Ku, Sapporo, Hokkaido 002–8003, Japan
3. Department of Veterinary Medicine, Yamaguchi University, Yoshida, Yamaguchi 753–0815, Japan
4. Department of Bacteriology-I, National Institute of Infectious Diseases, Toyama, Shinjuku, Tokyo 162–8640, Japan
5. Faculty of Pharmacy, Chiba Institute of Science, Choshi, Chiba 288–0025, Japan