The New Mexico Department of Agriculture (NMDA) and the New Mexico Livestock Board (NMLB) have confirmed the first case of equine herpes myeloencephalopathy (EHM) in the state. The neurologic disease, which is associated with Equine Herpesvirus-1 (EHV-1), was detected in a horse located in Doña Ana County.
The affected animal had recently attended the 2025 Women’s Professional Rodeo Association World Finals and Elite Barrel Race held in Waco, Texas, from November 5 to 9. Officials report that the horse is now isolated from other animals and is recovering with veterinary care.
This confirmation follows similar reports from the Texas Animal Health Commission and the Oklahoma Department of Agriculture, Food, and Forestry, who announced EHM cases after equine events involving participants from multiple states, including New Mexico.
EHV-1 is a highly contagious virus impacting horses, donkeys, and mules. It spreads through respiratory secretions as well as shared equipment, trailers, or contaminated environments. While it poses no risk to humans, it can cause respiratory illness, abortions in pregnant mares, foal death, and severe neurological symptoms such as fever, nasal discharge, cough, lethargy, hindlimb weakness, difficulty rising, loss of tail tone or urinary retention. In serious cases horses may be unable to stand.
“Immediate isolation and veterinary evaluation are the most effective tools we have,” said state veterinarian Dr. Samantha Holeck. “Horse owners should closely monitor their animals and practice heightened biosecurity, especially if they recently attended events in Texas or Oklahoma.”
Veterinarians use PCR testing on nasal swabs and blood samples for accurate diagnosis. State officials stress that early detection and strict isolation of symptomatic horses are crucial for preventing further spread.
There is currently no cure for EHV-1; however most respiratory cases recover fully with supportive care. Horses affected by reproductive issues also typically improve. Neurologic cases have variable outcomes; severe paralysis often results in a poorer prognosis.
State officials advise horse owners to follow veterinary vaccination guidance; isolate new arrivals for two to three weeks before mixing them with other animals; avoid sharing equipment like halters or grooming tools; disinfect barns regularly; monitor temperatures daily during periods of increased risk; and limit movement during regional outbreaks.
