1. Clinical Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
2. Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, 2-11, Inada, Obihiro, Hokkaido 080-8555, Japan
3. Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine, 2-11, Inada, Obihiro, Hokkaido 080-8555, Japan
4. Field Center of Animal Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, 2-11, Inada, Obihiro, Hokkaido 080-8555, Japan
5. Department of Life Science and Agriculture, Obihiro Univerisity of Agriculture and Veterinary Medicine, 2-11, Inada, Obihiro, Hokkaido 080-8555, Japan
6. Department of Population Medicine and Diagnostic Sciences, Cornell University, College of Veterinary Medicine, Ithaca, NY 14853, U.S.A.