In many horses, the only sign of infection with EHV-1 is fever, which may go unnoticed.
On March 5, 2018, the Director of the Arizona Department of Agriculture (AZDA) Mark Killian ordered the quarantine of a cutting horse facility in northern Maricopa County after a nasal swab on a gelding tested positive for equine herpesvirus 1 (EHV-1) "wild strain".
On Friday, March 2, 2018, Peter Mundschenk, DVM, the Arizona state veterinarian, received a notification confirming the diagnosis of equine herpes myeloencephalopathy (EHM) in a Quarter Horse gelding with a positive nasal swab from EHV- 1. This horse had been at the South Point Arena in Las Vegas earlier this month for a cutter horse event and also attended the Arizona Cutting Horse Association (ACHA) show in Queen Creek over the weekend before developing neurological signs.
The ACHA also approached all contestants to advise them to observe all the horses that attended the events in search of signs of disease and to contact their veterinarians to perform the tests, as they could have been exposed. The event center in Queen Creek is in the process of performing a second disinfection of the facility.
Equine herpesvirus-1 is highly contagious among horses, but does not pose a threat to humans. Symptoms in horses may include fever, runny nose, swelling in the leg (fluid swelling), unsteady gait, weakness in the extremities, dribbling of the urine, and decreased tone of the tail. The virus spreads easily by airborne transmission, horse-to-horse contact and contact with nasal secretions in the equipment, stickiness, nourishment and other surfaces. Caregivers can transmit the virus to horses if their hands, clothing, shoes or vehicles are contaminated.
Mundschenk encouraged Arizona horse owners who could have been at these events to take their horses' temperature twice a day. If a horse reaches a temperature greater than 101.5 or shows any of the listed signs, the owner must isolate it from other horses at the facility and contact a veterinarian to draw blood and obtain nasal swabs. Contact the State Veterinary Office at 602 / 542-4293 if you have questions about this quarantine. Arizona veterinarians must report any horse that shows neurological signs to the state veterinarian immediately.