EHV-1/EHM Update
Outbreak Linked to Barrel Racing Events in Texas and Oklahoma
The Montana Department of Livestock (MDOL) is closely monitoring a multi-state outbreak of Equine Herpesvirus-1 (EHV-1), specifically the neurologic form known as Equine Herpes Myeloencephalopathy (EHM). This outbreak is linked to recent barrel racing events in Texas and Oklahoma.
Key Facts About the Outbreak:
The first reported case involved a horse that competed at the 2025 WPRA World Finals and Elite Barrel Race in Waco, Texas, from November 5–9, 2025.
Additional cases have been reported in horses that attended events in Stephenville, TX, and Guthrie, OK.
At least seven confirmed cases have been identified across Texas, Oklahoma, and Louisiana, with roughly two dozen more suspected cases in multiple states.
Large events like these bring together hundreds of horses from multiple states and Canadian provinces, increasing the potential for disease spread.
Current Situation in Montana:
There are currently no confirmed EHM cases in Montana.
MDOL is taking precautionary measures, including emergency rules requiring equine health certificates (CVI) issued within 72 hours of entry into Montana.
Risk and Precautions:
EHV-1 is common in the general horse population, but it can cause serious illness, including:
Respiratory disease (mainly in young horses)
Abortion
Neurologic disease (EHM), which can present with fever, nasal discharge, lack of coordination, hindquarter weakness, lethargy, and other signs
Transmission occurs through aerosolized secretions or contaminated equipment, tack, hands, and trailers. Horse owners and event organizers are urged to follow strict biosecurity measures:
Monitor horses’ temperatures twice daily
Isolate horses showing fever or neurological signs
Consider postponing or canceling events that bring in out-of-state horses
Follow all state-specific movement and import restrictions
Resources for Horse Owners and Veterinarians:
USDA EHM Incidence Guidance
This outbreak highlights the importance of timely disease reporting, careful monitoring, and strict biosecurity, particularly at large equine events. Horse owners are encouraged to remain vigilant and consult their veterinarians if they suspect illness in their animals.
This information is from the Montana Department of Livestock.
If you have concerns about your own horses, please reach out to CMVS.
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