ANNAPOLIS, MD—The Maryland Department of Agriculture’s Animal Health Program confirmed this week that a horse in Baltimore County had tested positive for equine herpesvirus (EHV-1).

Samples from the symptomatic horse were sent to the Frederick Animal Health Laboratory, where the non-neurotropic strain of EHV-1 was confirmed.

The horse was euthanized on Thursday due to complications.

The Baltimore County farm, which has not been identified, has been placed on a hold order by the department, prohibiting movement on or off the farm until any exposed horses have been cleared for release.

The horse was previously housed in an isolated barn with three other horses. The farm stables a total of 25 horses, none of which are showing clinical signs of EHV-1 or fever at this time.

The veterinary practitioner and stable are providing follow-up care to the asymptomatic horses on the farm. Possible links to the positive EHV-1 equine are actively being investigated.

Equine herpesviruses are viruses that are found in most horses all over the world. Almost all horses have been infected with the virus and have no serious side effects. It is currently unknown what causes some infected horses to develop the serious neurological forms that may be fatal.

To date, nine EHVs have been identified, worldwide. Equine herpesvirus myeloencephalopathy (EHM) is another name for the neurologic disease associated with equine herpesvirus (EHV) infections.

Owners are cautioned to monitor horses at their premises carefully, and should contact their private veterinarians to arrange for equine herpesvirus testing if a horse exhibits significant temperature elevations or neurologic signs.

Veterinarians are required to report equine neurologic syndrome to the department by calling the Animal Health Program at 410-841-5810.