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.

Disease

Outbreak States

Start Date

End Date

Equine Herpesvirus- Neurologic

Alameda County, CA

Outbreak Identifier: 6793

Alert ID: 4289

April 02, 2025

Confirmed Case(s) - Official Quarantine

Source: California Department of Food and Agriculture

Number Confirmed: 1;
Number Exposed: 75;

Horse 1:
Age: 22; Gender: Mare; Breed: Trakhener; Clinical Signs: ataxia, limb edema, trouble urinating;

Comments: A 22-year-old Trakehner mare from Alameda County displaying neurologic signs was confirmed positive for Equine Herpesvirus Myeloencephalopathy (EHM) secondary to Equine Herpesvirus-1 (EHV-1). The mare is currently under veterinary care at an off-site veterinary hospital and is showing daily improvement clinically. Seventy-five (75) potentially exposed horses at the home premise in Alameda County were quarantined on April 1st with enhanced biosecurity measures implemented. CDFA has been onsite and will continue to actively monitor the situation.;

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