1. The United Graduate School of Veterinary Science, Yamaguchi University, 1677–1 Yoshida, Yamaguchi 753–8515, Japan
2. Department of Veterinary Surgery, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677–1 Yoshida, Yamaguchi 753–8515, Japan
3. Department of Gastroenterology and Hepatology, Yamaguchi University Graduate School of Medicine, Minami-Kogushi 1–1–1 Ube, Yamaguchi 755–8505, Japan
4. Animal Medical Center, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677–1 Yoshida, Yamaguchi 753–8515, Japan
5. Department of Veterinary Nursing and Technology, Nippon Veterinary and Life Science University, 1–7–1 Kyonan-cho, Musashino, Tokyo 180–8602, Japan
6. Division of Small Animal Surgery, Department of Veterinary Science, Faculty of Agriculture, Iwate University, 3–18–8 Ueda, Morioka, Iwate 020–8550, Japan