California Horse Confirmed EHV-1 Positive

The California Department of Food and Agriculture (CDFA) released a statement Sept. 13 indicating that on Sept. 12, a mare from Tuolumne County tested positive for the neurologic strain of equine herpesvirus-1 (EHV-1). Three additional California horses have tested positive for the virus in the past several weeks.

"The mare is isolated, quarantined, and undergoing treatment at a veterinary referral hospital," the release said, adding that an epidemiologic investigation is under way at the horse's home facility.

"The premises of origin have been quarantined and the potentially exposed animals on the premises are being monitored," the release added.

Meanwhile, the CDFA released another statement indicating that the quarantine of the home premises of the other three horses has been lifted.

"Epidemiologic investigation conducted by CDFA reveals minimal disease risk based on lack of animal movement on and off the affected premises," the statement read. "The affected premises were quarantined and the 13 other horses on the property were temperature monitored twice daily and observed for clinical signs for 21 days. No additional horses have demonstrated a fever or any other compatible clinical signs. On September 13, the quarantine was released."

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.

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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