1. Laboratory of Veterinary Physiology, School of Veterinary Medicine, Kitasato University , Towada 034-8628 , Japan
2. Clinic for Small Domestic Animals and Radiology, Faculty of Veterinary Medicine, Mahanakorn University of Technology , Bangkok 10530 , Thailand
3. Department of Veterinary Clinical Pathobiology, Graduate School of Agricultural and Life Sciences, University of Tokyo , Tokyo 113-0032 , Japan
4. Laboratory of Veterinary Physiology, College of Veterinary Medicine, Okayama University of Science , Imabari 794-8885 , Japan