According to the Maryland Department of Agriculture, a horse that was at the same breeding facility as a Montgomery County horse that was recently diagnosed with the mutant neurotropic form of Equine Herpes Virus (EHV-1) has tested positive for EHV-1. This second horse, which is still at the breeding facility, had no symptoms and was diagnosed as the result of lab tests. Both EHV-1 positive horses are under care by private veterinarians and are in strict isolation, according to protocol.
The Montgomery County horse had been at the breeding facility for more than two weeks before returning home on Monday. While at the breeding facility and during her first day home, she exhibited no signs of illness. On Tuesday, the horse began showing mild respiratory and neurological signs and was seen by a private veterinarian, who reported the suspected neurological illness to the Maryland Department of Agriculture (MDA), as is required by law. Laboratory tests conducted by MDA confirmed the diagnosis. Following a Disease Investigation Protocol, MDA tested horses that were in close contact with the sick horse at the breeding facility. That investigation discovered the second positive horse.
All horses that were exposed to the two positive horses are currently free of symptoms and are being monitored daily. All appear healthy. Both farms will remain under quarantine to ensure the virus is contained. As of today, MDA believes the virus is contained to these two farms and is not aware of any other EHV-1 cases in the state.
MDA’s Animal Health Program continues to monitor the situation closely. Owners should contact their private veterinarians to arrange for EVH testing if a horse exhibits significant temperature elevations or neurologic signs. Veterinarians are required to report equine neurologic syndrome to MDA.