The New Mexico Department of Agriculture and the New Mexico Livestock Board have confirmed the state’s first case of equine herpes myeloencephalopathy (EHM), a serious neurological disease linked to Equine Herpesvirus-1 (EHV-1). In response, authorities are urging horse owners to implement immediate preventive measures to curb the spread of this highly contagious virus.
The affected horse, located in Doña Ana County, had recently participated in the 2025 Women’s Professional Rodeo Association World Finals and Elite Barrel Race in Waco, Texas, from November 5 to 9. Following the announcement, the village of Corrales cancelled its annual Christmas de los Caballos All Equine Parade and Food and Toy Drive, originally scheduled for November 23. The horse is currently isolated and receiving supportive veterinary care, showing signs of improvement.
In the wake of this case, both the Texas Animal Health Commission and the Oklahoma Department of Agriculture, Food, and Forestry have reported confirmed cases of EHM in their states as of November 18. These findings come after multiple equine events attended by horses from various states, including New Mexico.
EHV-1 is a common and highly contagious virus that can affect horses, donkeys, and mules. It spreads through respiratory secretions, shared equipment, trailers, and contaminated environments. While it poses no threat to humans, it can lead to severe health issues in horses, including respiratory illness, abortions, and neurologic conditions such as EHM. Symptoms of EHM may include fever, nasal discharge, cough, lethargy, hindlimb weakness, difficulty rising, loss of tail tone, urinary retention, and in severe cases, an inability to stand.
Dr. Samantha Holeck, the state veterinarian, emphasized the importance of immediate isolation and veterinary evaluation as the most effective measures against the spread of the disease. She stated, “Horse owners should closely monitor their animals and practice heightened biosecurity, especially if they recently attended events in Texas or Oklahoma.”
Diagnosis of EHV-1 involves PCR testing of nasal swabs and whole blood, which provides the most accurate results. State officials stress that early testing and strict isolation of any horse displaying signs of illness are crucial to preventing further outbreaks. Although there is no cure for the virus, most respiratory cases recover fully with supportive care, while neurologic cases vary widely in prognosis.
To minimize the risk of EHM, state officials recommend that horse owners adhere to several key practices. Resources for additional information are available from the New Mexico Livestock Board, the New Mexico Department of Agriculture, the American Association of Equine Practitioners, and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.
For specific inquiries regarding EHV-1 testing, horse owners can contact NMDA’s Veterinary Diagnostic Services at 505-383-9299. For any regulatory or livestock health concerns, the New Mexico Livestock Board can be reached at 505-841-6161. It is advised that horse owners consult their veterinarians for guidance on diagnosis, treatment, and vaccination options.
