An outbreak of a particularly aggressive strain of equine herpesvirus-1 (EHV-1), causing equine herpesvirus myeloencephalopathy (EHM), originated at the Women’s Professional rodeo Association World Finals in Waco, Texas, in early November. Since then, 15 confirmed EHM cases have been reported across Texas, Oklahoma, Louisiana, Colorado, and New Mexico, with two horses euthanized in Texas. The virus’s incubation period and asymptomatic shedding have raised concerns about its rapid spread, prompting some event cancellations and postponements, especially in Texas and nearby states. The Texas Animal Health Commission recommends canceling or postponing horse events to curb transmission, while other venues in Florida and Colorado have also taken precautionary measures.

The U.S. Equestrian Federation (USEF) is monitoring the situation closely but supports continuing USEF-licensed events with biosecurity protocols in place, as no cases have been linked to these events so far. USEF advises event organizers to consult local veterinarians and implement strict biosecurity measures. Meanwhile, some major venues like Carolina Horse Park and Wellington International plan to proceed with scheduled competitions, relying on established health protocols and veterinary guidance. Interstate horse movement now requires current certificates of veterinary inspection due to the outbreak, reflecting heightened efforts to control the disease’s spread.