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EHV-1 Outbreak Spreads Through U.S. Horse Community
An outbreak of Equine Herpesvirus Myeloencephalopathy (EHM), caused by EHV-1, is currently affecting horses in multiple states across the U.S. The outbreak traces back to a major equine event in Waco, Texas in early November 2025, and has since spread to at least eight states, including Texas, Oklahoma, Louisiana, Arizona, Colorado, New Mexico, South Dakota, and Washington.
What Is EHV-1 / EHM
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EHV-1 is a virus that typically affects the respiratory system but can also cause more serious neurologic disease (EHM), abortions in pregnant mares, or stillbirths.
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Transmission is rapid and can happen through direct horse-to-horse contact, aerosolized respiratory droplets (from coughing or nasal discharge), or indirectly through contaminated equipment, tack, water/food buckets, stalls, trailers, and even clothing or human handlers — meaning humans can inadvertently spread the virus between barns.
Symptoms to Watch For
Horses infected with EHV-1 may show a range of signs. Common indicators:
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Fever (watch for temperatures over 101.5 °F)
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Nasal discharge or runny nose, coughing, and lethargy
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Swollen lymph nodes, lack of appetite, and unusual tiredness
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In more severe neurologic cases (EHM): incoordination, stumbling, hind-limb weakness or inability to stand, urine dribbling, and paralysis — sometimes with little to no respiratory signs first.
Because some horses may not show obvious signs immediately, monitoring temperature twice daily is strongly recommended for at least two weeks after possible exposure.
Scale & Impact of the 2025 Outbreak
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As of December 1, 2025, at least 37 confirmed EHV-1/EHM cases are directly linked to the Waco, Texas event — with some horses requiring euthanasia.
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Multiple states have reported cases and issued advisories, prompting cancellations or postponements of rodeos and horse events to reduce spread.
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The outbreak has heightened concern among veterinarians and horse owners, especially those whose horses traveled recently to events or have mingled with exposed animals.
What Horse Owners Should Do: Biosecurity & Prevention
To protect your barn and horses, consider these guidelines:
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Isolate and monitor: Any horse that attended a recent show or rodeo event — especially those linked to known EHV-1 outbreaks — should be isolated for a minimum 14 days, and preferably longer if symptoms appear.
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Temperature checks: Take rectal temperatures twice daily for exposed or new horses; fever may be the first or only early sign.
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Strict hygiene: Disinfect tack, buckets, stalls, trailers; avoid sharing equipment; wear clean clothing and boots; thoroughly wash hands before interacting with other horses.
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Limit travel and mixing: Postpone unnecessary hauling, competitions or social barn events until the outbreak is under control.
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Work with your veterinarian: If symptoms appear — even mild — contact your vet immediately. They can recommend quarantine, testing (PCR/swab), and appropriate care or referral to isolation facilities if needed.
Final Thoughts
The 2025 EHV-1 / EHM outbreak is a serious reminder of how quickly equine diseases can spread through events and travel — and how important vigilance and biosecurity are for every horse owner, farm, and barn. Even if you haven’t attended a major event, keeping a clean barn environment, limiting unnecessary contacts, and monitoring your horses carefully can make a big difference.
If you own or care for horses right now, use this time to review your biosecurity routine, stay alert for signs, and consult with your veterinarian about vaccination status and precautions. Let’s keep our horses healthy, barns safe, and communities strong.