1. Haemaru Referral Animal Hospital, Seongnam 463-050, Korea.
2. Department of Veterinary Internal Medicine, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea.
3. Department of Veterinary Medical Imaging, College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, Korea.
4. Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea.