Author's Organization:Department of Veterinary Microbiology,Obihiro Zootechnical University Department of Veterinary Microbiology,Obihiro Zootechnical University Department of Veterinary Microbiology,Obihiro Zootechnical University Department of Veterinary Microbiology,Obihiro Zootechnical University Department of Veterinary Pathology,Obihiro Zootechnical University