1. Department of Veterinary Pathology; School of Veterinary Medicine; Rakuno Gakuen University; Ebetsu Hokkaido 069-8501 Japan
2. Department of Veterinary Biochemistry; School of Veterinary Medicine; Rakuno Gakuen University; Ebetsu Hokkaido 069-8501 Japan
3. Department of Epizootiology; School of Veterinary Medicine; Rakuno Gakuen University; Ebetsu Hokkaido 069-8501 Japan
4. Otaru Aquarium; 3-303 Shukutsu Otaru Hokkaido 047-0047 Japan