Outbreaks | Equine Disease Communication Center

Updates on current disease outbreaks are listed here as they occur and will include the date listed, disease name, location and current status. Specific premises will not be named but the general location by town, county and state will be listed. When locations, events or horses are at risk they will be listed. Updates will be posted as they are received.

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West Nile Virus

Sacramento County, CA

Outbreak Identifier: 7106

Alert ID: 4626

September 30, 2025

Confirmed Case(s) - No Quarantine

Source: California Department of Food and Agriculture

Number Confirmed: 1;

Horse 1:
Age: 1; Gender: Colt; Breed: Friesian; Onset of Clinical Signs: 9/22/2025; Clinical Signs: ataxia (worse in hind end), hyperreactive, muscle fasciculations, hypermetric front end; Confirmation Date: 9/29/2025; Vaccination Status: Unvaccinated;

Comments: The fifth (5th) case of West Nile Virus in California in 2025 was confirmed in Sacramento County. On September 29, 2025, an unvaccinated 1-year-old Friesian stallion in Yolo County displaying neurologic signs was confirmed positive for West Nile Virus. The last known status of the stallion is that it is alive and recovering.;

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