EHM Confirmed in Virginia Horse


~ State Veterinarian commends farm in Fauquier County for quick action that led to early detection and may have prevented spreading the disease ~

Dr. Richard Wilkes, State Veterinarian with the Virginia Department of Agriculture and Consumer Services (VDACS), says that the VDACS Office of Veterinary Services has completed the initial investigation of the Equine Herpesvirus Myeloencephalopathy (EHM) case recently reported in Northern Virginia. VDACS field veterinarians have reported that horses from the farm did not have contact with other horses in the state.  “EHM is a highly contagious disease,” Wilkes said, “but we did not find any additional horses displaying fevers or clinical signs of the disease on the farm over the weekend. The disease can appear in horses that have not been exposed to horses showing disease signs, however, so we are still monitoring the situation carefully and advise horse owners to continue to practice strict biosecurity.”

On Friday, April 11, VDACS announced that a single horse in Northern Virginia had tested positive for EHM and was euthanized. The horses on that farm in The Plains in Fauquier County will remain under quarantine for 21 to 28 days from the last exposure to the virus, the incubation period for EHM.

Wilkes commends farm management and their veterinarian at the Fauquier farm for their quick recognition of the clinical signs and for initiating the testing that led to the diagnosis of EHM. Although he still urges horse owners to prevent contact of healthy horses with any that may be exposed to EHM infected horses, he says the rapid detection of disease in the initially infected horse may have helped limit the scope of this disease event. “The farm management kept excellent records of movement on and off the farm that provided excellent information for VDACS staff to identify exposures of other horses,” he said.

Horses from the Fauquier farm did leave that farm and go to two other states. VDACS has notified the State Veterinarians in the affected states of the situation.

Wilkes advises horse owners to continue to practice strict biosecurity, especially when horses are commingled. He recommends placing horses in isolation when returning from events and monitoring their temperature upon return as important disease protection and early detection measures.


Dr. Richard Wilkes, State Veterinarian with the Virginia Department of Agriculture and Consumer Services (VDACS), announced this afternoon that a horse in Virginia has been confirmed positive for Equine Herpesvirus Myeloencephalopathy (EHM), a neurological disease of horses caused by Equine Herpesvirus-1 (EHV-1). The affected horse is from Northern Virginia and was euthanized late today. Diagnostic samples were submitted to the VDACS Regional Animal Health Laboratory System by a private practice veterinarian because the horse had experienced a fever for three days and began to have neurological signs compatible with EHM.

VDACS officials advise that strict biosecurity is the most effective way to minimize the risk of spreading the virus. Field veterinarians have started the epidemiological investigation that will be necessary to assess the risk that the disease may be present in other horses or farms. The potential for EHV-1 to cause Equine Herpesvirus Myeloencephalopathy is influenced by a number of factors and case reports vary from involving a single horse to very large numbers of cases. VDACS will monitor the situation continuously and urges all horse owners in Virginia to minimize nonessential contact with other horses and to enhance their biosecurity practices on and off of the farm to prevent the spread of this and other infectious diseases. Horse owners should consult their veterinarians about specific ways to minimize the risk of EHV-1 infection on their farms.

The symptoms of EHM in horses may include a fever, nasal discharge, wobbly gait, hind-end weakness and dribbling of urine. The disease is often fatal. The virus is easily spread by airborne transmission, horse-to-horse contact and by contact with nasal secretions on equipment, tack, feed and other surfaces. Caretakers can spread the virus to other horses if their hands, clothing, shoes or vehicles are contaminated. EHV-1 poses no threat to human health.

VDACS recommends the following biosecurity measures for all horses that will come into contact with other horses at shows, trail rides, meets and other events:

  • Minimize direct contact between assembled horses whenever possible.
  • Clean and disinfect equipment, feed, tack, stalls and other surfaces that are shared between horses.
  • Isolate and closely monitor horses that are returning from a show, trail ride or competition for a minimum of 14 days.
  • Clean and disinfect caretakers’ hands, clothing, shoes and vehicles that may be contaminated by other horses or equipment.
  • Consult with your veterinarian about a vaccination schedule for diseases of concern such as Eastern Equine Encephalitis, West Nile Virus, Equine Rhinopneumonitis and rabies. Your equine veterinarian can also provide you with biosecurity recommendations that are specifically tailored to your horses and your facility.

Horse exhibitors and event goers can monitor their horses for early signs of infection by taking their temperature twice a day while at shows and reporting an elevated temperature to their veterinarian.  Veterinarians should report suspected cases of EHM to the Office of Veterinary Services in the Virginia State Veterinarian’s office at 804.786.2483.

More information on EHV-1 is available at A downloadable brochure about horse biosecurity is available on the USDA website