{"title":"The 2025 outbreak of equine influenza among draft horses at Obihiro Racecourse, Hokkaido, Japan.","authors":"Natsuko Fukumoto, Makoto Shibata, Mayu Hayashi, Kyoko Kawauchi, Yukiko Yabuuchi, Yasuhiro Oue, Ryota Matsuyama, Takehisa Yamamoto, Hiroshi Mita, Nanako Kawanishi, Hiroshi Bannai, Koji Tsujimura, Takashi Yamanaka, Manabu Nemoto","doi":"10.1292/jvms.26-0092","DOIUrl":null,"url":null,"abstract":"<p><p>In 2025, an outbreak of equine influenza occurred among draft horses at Obihiro Racecourse in Hokkaido, Japan. The number of horses showing clinical signs increased dramatically in April. The proportion affected was significantly higher in 2-year-olds than in older groups. The proportion that developed fever during the outbreak was significantly higher than that observed among Thoroughbreds during the 2007 outbreak. In non-epidemic periods, the geometric mean hemagglutination inhibition antibody titer of 2-year-old draft horses was significantly lower than that of 2-year-old Thoroughbreds. These draft horses had received fewer vaccinations than the Thoroughbreds. Less frequent vaccination likely led to a lower antibody titer and a higher final attack rate in the 2-year-olds and in the overall draft horse population.</p>","PeriodicalId":49959,"journal":{"name":"Journal of Veterinary Medical Science","volume":" ","pages":"774-777"},"PeriodicalIF":1.1000,"publicationDate":"2026-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Veterinary Medical Science","FirstCategoryId":"97","ListUrlMain":"https://doi.org/10.1292/jvms.26-0092","RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2026/3/25 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"VETERINARY SCIENCES","Score":null,"Total":0}
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Abstract
In 2025, an outbreak of equine influenza occurred among draft horses at Obihiro Racecourse in Hokkaido, Japan. The number of horses showing clinical signs increased dramatically in April. The proportion affected was significantly higher in 2-year-olds than in older groups. The proportion that developed fever during the outbreak was significantly higher than that observed among Thoroughbreds during the 2007 outbreak. In non-epidemic periods, the geometric mean hemagglutination inhibition antibody titer of 2-year-old draft horses was significantly lower than that of 2-year-old Thoroughbreds. These draft horses had received fewer vaccinations than the Thoroughbreds. Less frequent vaccination likely led to a lower antibody titer and a higher final attack rate in the 2-year-olds and in the overall draft horse population.
期刊介绍：
JVMS is a peer-reviewed journal and publishes a variety of papers on veterinary science from basic research to applied science and clinical research. JVMS is published monthly and consists of twelve issues per year. Papers are from the areas of anatomy, physiology, pharmacology, toxicology, pathology, immunology, microbiology, virology, parasitology, internal medicine, surgery, clinical pathology, theriogenology, avian disease, public health, ethology, and laboratory animal science. Although JVMS has played a role in publishing the scientific achievements of Japanese researchers and clinicians for many years, it now also accepts papers submitted from all over the world.
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