1. Department of Veterinary Internal Medicine, College of Veterinary Medicine, Seoul National University, Gwanak-ro 599, Gwanakgu, Seoul 151-742, Korea
2. Department of Veterinary Internal Medicine and Geriatrics, and Institute of Veterinary Science College of Veterinary Medicine, Kangwon National University, Gangwondo, 200-701, Korea
3. Department of Veterinary Surgery, College of Veterinary Medicine, Kangwon National University, Gangwondo, 200-701, Korea
4. Department of Anatomy, College of Veterinary Medicine, Kangwon National University, Ganwondo, 200-701, Korea