Six stables in Delaware are under official quarantine after a horse that displayed neurologic signs was confirmed positive for equine herpesvirus-1 (EHV-1).

The affected horse was euthanatized Jan. 17. While polymerase chain reaction (PCR) tests on nasal swab samples confirmed the horse to be positive for EHV-1, additional tests to determine whether it’s the neurogenic strain are still pending, according to State Veterinarian Sara Busch, DVM.

Delaware officials performed a trace-back and initially identified 11 animals exposed to the affected horse, which lived in the Felton/Frederica area. Stables with exposed horses are now under a 21-day quarantine. Horses’ temperatures are to be monitored twice daily, and no animals allowed to enter or exit the premises. More information is available on the Delaware Department of Agriculture Web site.

Two Maryland horses were originally included in the implicated group. Investigators with the Maryland Department of Agriculture have since concluded that these horses were not exposed.

“This confusion is common in all such investigations, as preliminary information is scarce, incomplete, and often contradicts other available information,” said Maryland State Veterinarian Guy Hohenhaus, DVM. “Investigators take great care to be inclusive in their initial fact finding and then systematically eliminate from consideration animals or premises where there is little or no risk. This case illustrates that concept well.”

There are no restrictions on any Maryland farms or animals at this time. A statement released by the Department encouraged horse owners to be vigilant in their biosecurity efforts.

Equine herpesvirus-1 is a form of herpesvirus that can cause fevers and neurologic signs that range from incoordination and weakness in the hind limbs to paralysis. Precautions are necessary because EHV-1 is highly contagious and can spread through the air. It can also be passed on shared tack and barn equipment, as well as human hands and clothing, making tight biosecurity essential to stop it from spreading.

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