On August 15, the Virginia Department of Agriculture and Consumer Services (VDACS) reported that its Animal Health Laboratory in Warrenton confirmed a diagnosis of Equine Herpesvirus-1 (EHV-1) on two horses from Culpeper County. One horse is undergoing supportive therapy at the Marion duPont Scott Equine Medical Center (EMC) in Leesburg and the other was euthanized.

Equine Herpes Virus (EHV-1) infection in horses can cause respiratory disease, abortion in mares, neonatal foal death and/or neurologic disease. The neurologic disease caused by the neurologic strain of EHV-1 is called Equine Herpes Virus Myeloencephalopathy (EHM).

There have been no new cases of EHM in Culpeper or elsewhere in Virginia. The infected horses originated from a small private farm in Culpeper County. All exposed horses are under quarantine and are being monitored twice daily for fever (temperature over 101.50 F) and other clinical signs. If no new cases occur, the farm will remain quarantined with no equids allowed on or off until September 4th. There had been no movement of horses off the premises in the month preceding the first diagnosed case on the farm.

The EMC is not under quarantine. Staff there worked with VDACS earlier to develop a plan to hospitalize infectious horses, specifically EHM, following isolation and biosecurity protocols, and those protocols were followed in this case.

The vaccine history of these horses is uncertain. While there are vaccines against the EHV-1 virus, the vaccines are ineffective against the neurologic strain.

The Equine Disease Communications Center Biosecurity web pages has more information on best practices for disease prevention in horses: equinediseasecc.org/biosecurity and VDACS has more information on EHV-1 at

vdacs.virginia.gov/animals-equine-herpes-virus.shtml. Horse owners also may contact VDACS’ Office of Veterinary Services at 804.786.2483.