1. Medicinal Safety Research Laboratories, Daiichi Sankyo Co., Ltd., Kitakasai, Edogawa, Tokyo 134–8630, Japan
2. Cooperative Department of Veterinary Medicine, Iwate University, Morioka, Iwate 020–8550, Japan
3. United Graduate School of Veterinary Science, Gifu University, Gifu 501–1193, Japan