1. Department of Veterinary Medicine, Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-0834, Japan
2. Department of Veterinary Pathology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
3. Japan Animal Referral Medical Center Kawasaki, Kanagawa 213-0032, Japan