1. Laboratory of Pathology, School of Life and Environmental Science, Azabu University, Kanagawa, Japan
2. Laboratory of Veteinary Pathology, School of Veterinary Medicine, Azabu University, Kanagawa, Japan
3. Laboratory of Environmental Analysis, School of Life and Environmental Science, Azabu University, Kanagawa, Japan
4. Hokkaido Research Station, National Institute of Animal Health, Hokkaido, Japan