1. Clinical Science & Pathobiology Division; Equine Research Institute, Japan Racing Association; Tokami-Cho 321-4 Utsunomiya Tochigi 320-0856 Japan
2. Microbiology Division; Epizootic Research Center, Equine Research Institute, Japan Racing Association; Shiba 1400-4 Shimotsuke Tochigi 329-0412 Japan
3. Racehorse Clinic, Ritto Training Center, Japan Racing Association; Misono 1028 Ritto Shiga 520-3085 Japan
4. Department of Domestic Animal Internal Medicine; Clinical Veterinary Science; Veterinary Medicine; Joint Faculty of Veterinary Medicine; Kagoshima University; Korimoto 1-21-24 Kagoshima Kagoshima 890-0065 Japan