1. Dairy Hygiene Unit, Division of Pathology and Pathophysiology, Hokkaido Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, 4 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-0045, Japan
2. NOSAI Minami, 401-4 Shinotsu, Ebetsu, Hokkaido 067-0055, Japan
3. Hokubu Veterinary Clinic, Chiba P.F.A.M.A.A, 99-1 Nira, Katori, Chiba 389-0407, Japan
4. Healthcare R&D Center, Asahi Kasei Corporation, 2-1 Samejima, Fuji, Shizuoka 416-8501, Japan