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

San Luis Obispo County, CA

Outbreak Identifier: 6705

Alert ID: 4186

January 17, 2025

Confirmed Case(s) - Official Quarantine

Source: California Department of Food and Agriculture

Number Confirmed: 1;
Number Exposed: 40;

Horse 1:
Age: 15; Gender: Mare; Breed: Thoroughbred (TB); Onset of Clinical Signs: 1/14/2025; Clinical Signs: ataxia, recumbency; Confirmation Date: 1/16/2025; Horse Status: Affected And Alive;

Comments: A 15-year-old Thoroughbred mare from San Luis Obispo County displaying neurologic signs was confirmed positive for Equine Herpesvirus Myeloencephalopathy (EHM) secondary to Equine Herpesvirus-1 (EHV-1). The mare is alive and under veterinary care at an off-site veterinary hospital. Forty (40) potentially exposed horses at the home premise in San Luis Obispo County were quarantined on January 17th with enhanced biosecurity measures implemented. There had been no recent history of travel on or off these premises by the clinical horse and no other horses on the home premises currently have any clinical symptoms. CDFA will continue to actively monitor the situation.;

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