The New Mexico Department of Agriculture (NMDA) and the New Mexico Livestock Board (NMLB) have confirmed the state's first case of equine herpes myeloencephalopathy (EHM), a neurological disease linked to Equine Herpesvirus-1 (EHV-1). The affected horse, located in Doña Ana County, had participated in the 2025 Women’s Professional Rodeo Association World Finals and Elite Barrel Race in Waco, Texas, from November 5 to 9. The animal is now isolated and receiving supportive veterinary care.
This case follows recent announcements by the Texas Animal Health Commission and the Oklahoma Department of Agriculture, Food, and Forestry about confirmed EHM cases in their states after equine events attended by horses from several states, including New Mexico.
EHV-1 is a highly contagious virus that impacts horses, donkeys, and mules. It spreads through respiratory secretions as well as shared equipment, trailers, and contaminated environments. While humans cannot contract EHV-1, it can cause respiratory illness, abortions, foal death, and severe neurological symptoms in horses. Signs include fever, nasal discharge, cough, lethargy, hindlimb weakness or paralysis, difficulty rising or standing, loss of tail tone or urinary retention.
“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 to diagnose EHV-1 accurately. State officials stress that early detection through testing and strict isolation of symptomatic animals are key steps to control further spread.
There is no cure for EHV-1; however, most respiratory cases recover with supportive care. Mares affected by reproductive forms also tend to improve with treatment. Neurological cases may vary in outcome depending on severity.
To reduce risk of infection among herds:
- Horse owners should follow vaccination advice from veterinarians.
- Newly acquired horses should be isolated for two to three weeks before joining other animals.
- Equipment such as halters or grooming tools should not be shared between animals.
- Regular disinfection of barns and tack is recommended.
- Daily temperature checks during periods of increased risk can help identify illness early.
- Movement of horses should be limited during local outbreaks.
