BISMARCK – Equine herpesvirus myeloencephalopathy (EHM) has been confirmed in two McHenry County horses.

The property has been quarantined and no other properties or horses have been identified as exposed at this time. North Dakota Department of Agriculture’s Animal Health Division is assisting the owner and local veterinarian.

EHM is caused by equine herpesvirus-1 (EHV-1) and occasionally equine herpesvirus-4 (EHV-4). EHV-1 is not uncommon and can cause respiratory disease, abortion, neonatal death and has a neurologic form of the disease that has become more common. EHM vaccines are available for the respiratory and reproductive forms of EHV-1. They do not reliably prevent the neurologic form, but may offer some level of protection. Vaccinating horses after exposure is not recommended.

“With summer coming, many horses will be moving to events around the region,” Agriculture Commissioner Doug Goehring said. “Care should be taken to reduce exposure to other horses and one should never bring a sick horse to an event.”

EHV-1 can be spread through the air, contaminated equipment, clothing and hands. Biosecurity measures that can reduce the risk of spreading the disease include avoiding shared food or water containers and preventing nose-to-nose contact.

Out-of-state horses and other equines entering North Dakota for any length of time must be accompanied by a certificate of veterinary inspection. These documents are helpful in locating and contacting an owner with potentially exposed horses when there is a disease concern.

Although highly infectious and contagious among horses, EHV-1 poses no threat to human health.