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Equine Neurologic Herpesvirus in San Mateo County, CA

On one property, a horse has tested positive for EHM and another has tested positive for EHV-1.
San Mateo County California map

On one property in San Mateo County, California, a pony mare has EHM and a Tennessee Walking Horse mare has a fever and tested positive for EHV-1.

The California Department of Food and Agriculture has reported that a 15-year-old pony mare, which originated from a San Mateo County facility, began displaying neurologic signs. She has been confirmed positive for equine herpesvirus myeloencephalopathy (EHM or neurologic herpesvirus). 

A 24-year-old Tennessee Walking Horse mare from the same property had a fever and tested positive for equine herpesvirus type 1 (EHV-1). 

Both mares have been isolated, placed under quarantine and enhanced biosecurity is in effect. 

Exposed horses will be monitored for clinical signs and temperatures will be taken twice daily. Any horse displaying a fever or compatible clinical signs will be tested. 

CDFA will continue to monitor the situation and post new information as it becomes available.

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