California EHV-1 Quarantines Released

The quarantines placed on two California farms after horses residing there tested positive for equine herpesvirus-1 (EHV-1) have been lifted, according to a statement from the California Department of Food and Agriculture (CDFA).

On Sept. 12 a Tuolumne County mare tested positive for the neurologic strain of EHV-1. The mare was treated at a referral hospital and a quarantine was implemented at her home facility.

On Sept. 15 seven additional horses from the mare's home premises were confirmed positive for EHV-1. Also on Sept. 15 the CDFA indicated that a second facility in San Joaquin County had been quarantined in relation to the Tuolumne County outbreak.

"Two horses displaying compatible clinical signs were confirmed positive for the neuropathogenic strain of EHV-1," a statement from the CDFA read. "These two horses were exposed to the virus on Sept. 4-10, while visiting the Tuolumne County premises."

On Oct. 5 the CDFA announced that the quarantines at both the Tuolumne County and the San Joaquin County properties had been lifted after no additional horses tested positive for the virus for 21 days.

Although it's not transmissible to humans, EHV-1 is highly contagious among horses and camelids, and it is generally passed from horse to horse via aerosol transmission (when affected animals sneeze/cough) and contact with nasal secretions. The disease can cause a variety of ailments in equines, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy (EHM, the neurologic form).

Myeloencephalopathy is characterized by fever, ataxia (incoordination), weakness or paralysis of the hind limbs, and incontinence. Should a horse with potential EHV-1 exposure display any of the aforementioned clinical signs, a veterinarian should be called to obtain samples and test for the disease.

About the Author

Erica Larson, News Editor

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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