County Monitors Equine Herpesvirus –1 Outbreak
Published on November 26, 2025
The Los Alamos County Community Services Department (CSD) reports that there are currently no known cases of Equine Herpesvirus-1 (EHV-1) or Equine Herpes Myeloencephalopathy (EHM) in the County. CSD staff is monitoring a multistate outbreak linked to the 2025 PRA World Finals in Waco, Texas (held Nov. 5-9) and the Barrel Futurities of America event in Guthrie, Oklahoma (held Nov. 17–18) where positive cases were confirmed. As a precaution, County staff is coordinating with local veterinarians and the State of New Mexico to be prepared should the situation change.
Regional animal health officials have confirmed a positive case in Doňa Ana County and additional cases in neighboring states including Utah, Colorado, and Arizona. Because horses from across the region attended the affected events, owners are encouraged to remain vigilant and closely monitor their animals.
According to the New Mexico Department of Agriculture (NMDA) Fact Sheet, EHV-1 is a common, highly contagious virus affecting horses, donkeys and mules. It spreads through respiratory secretions, shared contaminated equipment, trailers and environments. While it cannot infect humans, the virus can cause respiratory disease, abortions, foal death and a serious neurologic condition known as Equine Herpes Myeloencephalopathy (EHM). Clinical signs may include lethargy, nasal discharge, limb swelling, lack of coordination, hind-end weakness, urine dribbling, diminished tail tone, head tilt, or abortion in pregnant mares. Horses with suspected exposure, any of the above symptoms or a fever of 102.5°F or higher should receive immediate veterinary evaluation, including early testing, and immediate isolation to prevent further spread.
Preventive Measures
NMDA and the New Mexico Livestock Board urge horse owners to take immediate preventive measures as follows:
- Follow veterinary vaccination guidance
- Isolate new horses for 2-3 weeks before introducing them to the herd
- Monitor horse temperatures daily during high-risk periods
- Avoid sharing equipment such as halters, buckets and grooming tools
- Disinfect barns, footwear, tack, buckets, grooming tools, stalls, trailers, and other equipment using a 1:10 bleach solution or approved disinfectants after removing organic material
- Wash hands and sanitize before and after handling horses
- Limit horse movement and avoid traveling between barns or facilities
While there is no cure, early detection, strict isolation, and supportive care are critical for reducing transmission.
Horse owners are urged to monitor animals closely, follow vaccination recommendations, disinfect equipment, and avoid introducing new horses to herds during high-risk periods.
For questions, contact the New Mexico Department of Agriculture’s Veterinary Diagnostic Services at 505-383-9299, the New Mexico Livestock Board at 505-841-6161 or a local veterinarian. The number of cases in New Mexico and across the country can be tracked by visiting the Equine Disease Communication Center website.