1. Department of Veterinary Medicine, School of Veterinary Medicine, Rakuno Gakuen University, Hokkaido, Japan
2. School of Veterinary Medicine, Kitasato University, Aomori, Japan
3. College of Human and Social Sciences, Kanazawa University, Ishikawa, Japan
4. School of Veterinary Medicine, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan