1. Department of Veterinary Pathology; School of Veterinary Medicine; Rakuno Gakuen University; 582 Bunkyodai-Midorimachi Ebetsu Hokkaido 069-8501 Japan
2. Shadai Corporation; Hayakita Hokkaido 053-1432 Japan
3. Department of Epizootiology; School of Veterinary Medicine; Rakuno Gakuen University; 582 Bunkyodai-Midorimachi Ebetsu Hokkaido 069-8501 Japan