Calif., N.C. EHV-1 Quarantines Lifted

 State animal health officials in California and North Carolina have lifted quarantines on three premises where  horses had tested positive for equine herpesvirus-1 (EHV-1) last month. All three quarantines were put into place in early to mid-January.

North Carolina's first EHV-1 case was confirmed on Jan. 5 when a horse residing in Rockingham County tested positive for the neurologic form of the virus. The mare was admitted to and quarantined at North Carolina State University's College of Veterinary Medicine, and has since recovered.

On Feb. 9 the North Carolina Department of Agriculture & Consumer Services issued a statement indicating the month-long quarantine imposed on the mare's home facility had been lifted, as no additional horses showed any signs of the virus.

“It is a testament to our preparedness activities and the cooperation that we received from the College of Veterinary Medicine that we were able to respond so quickly to this virus,” said State Veterinarian David Marshall, DVM, in the statement. “This is a highly contagious virus, and cooperation from all parties was the key to ensuring that it didn’t spread any further.”

In California, two premises—one in Orange County and one in Riverside County—were quarantined after resident horses tested positive for EHV-1. Epidemiologic investigations on both outbreaks led the California Department of Food and Agriculture (CDFA) to conclude the two incidents were unrelated.

In Orange County 16 horses tested positive for EHV-1, beginning with the index case on Jan. 11. Only one horse (the index case) displayed neurologic signs and has reportedly recovered. One horse was euthanized on Jan. 18 after becoming recumbent; however, a necropsy led veterinarians to believe the recumbency was unrelated to the EHV-1.

In Riverside County a horse at a large multidiscipline facility tested positive for the neurologic form of EHV-1. The horse exhibited hind limb incoordination and urine dribbling, became recumbent, and was euthanized on Jan. 23.

On Feb. 14 the CDFA released a statement indicating no additional horses at either premises had displayed signs related to or tested positive for EHV-1, and that both facilities had been released from quarantine.

"Horse owners traveling to an equine event are reminded that there is always risk when horses of unknown health status are commingled at one location for a show or competition," the statement added. "The CDFA strongly recommends horse owners practice proper biosecurity when traveling to or stalled at an equine event. Consistent basic biosecurity practices play an important role in reducing risk of exposure to all contagious equine diseases when attending an event."

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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