1. Department of Veterinary Associated Science, Faculty of Veterinary Medicine, Okayama University of Science, Ikoinooka 1-3, Imabari, Ehime 794-8555, Japan
2. Animal Health Unit, Department of Health and Environmental Sciences, School of Veterinary Medicine, Rakuno Gakuen University, Bunkyodai-Midori 582, Ebetsu, Hokkaido 069-8501, Japan