A serious threat has emerged for horses across multiple states, and it's all due to a highly contagious virus. This virus, known as Equine Herpesvirus (EHV-1), has been linked to a recent rodeo event, causing concern among horse owners and veterinary professionals alike.
EHV-1 is a formidable opponent, capable of manifesting in various forms, including neurological, respiratory, and reproductive issues. While it may not always be deadly, severe cases of the neurological form, Equine Herpesvirus Myeloencephalopathy (EHM), can be fatal for the infected horse. Additionally, EHV-1 can lead to abortions in pregnant mares, making it a double-edged sword.
The virus spreads rapidly through contact with infected nasal discharge and aerosol droplets between horses. Surfaces like stalls, feed, tack, and vehicles can also become contaminated, further aiding its transmission. Even humans can inadvertently contribute to the spread by carrying the infection on their hands, clothing, or equipment.
The recent outbreak has been traced back to the Women's Professional Rodeo Association World Finals (WPRA) and Elite Barrel Race, held in Waco, Texas, in November 2025. Diagnostics revealed that at least five horses, two from Oklahoma and three from Texas, tested positive for EHV-1 after attending this event. These horses are now under quarantine at the Louisiana State University School of Veterinary Medicine (LSU Vet Med) Teaching Hospital in Baton Rouge.
Jared Janke, DVM, a clinical associate professor of equine internal medicine at the Texas A&M College of Veterinary Medicine and Biological Sciences, emphasized the importance of quarantine and reducing exposure. "The virus spreads easily and can transmit from horse to horse before any clinical signs appear," he said. "Preventing the movement of exposed horses is crucial to cutting off the main transmission routes."
The full extent of the outbreak remains unknown, but it has already led to the cancellation of the Barrel Futurities of America World Championship, scheduled for November 17-22, 2025, in Guthrie, Oklahoma. A local news report also revealed that a horse with EHV-1 was stabled on the Lazy E Arena grounds after testing positive for the virus.
Clinical signs of EHV-1 infection include fever, nasal discharge, enlarged lymph nodes, lethargy, and late-term abortions that can occur up to two months after infection. Signs of EHM include an inability to stand, incoordination, urine dribbling, high fever, and decreased sensation in the tail and perineal area.
Rose Baker, BVMS, DACVIM (LAIM), an associate professor of equine medicine at LSU Vet Med, advised horse owners to take immediate action if they suspect exposure. "Contact your veterinarian and quarantine the horse and any horses that have been exposed to that horse," she said. "Your veterinarian can submit samples to LSU Diagnostics to determine if a horse is shedding EHV-1."
During the 2- to 10-day incubation period, horses can shed the virus before showing any clinical signs. In cases of EHM, the incubation period may be even longer. "If you notice any signs of fever, hindlimb loss of coordination, urine dribbling, or weak tail tone, isolate the horse, stop the movement of any animals in contact, and contact your veterinarian immediately," Janke added. "Your veterinarian will guide you through the necessary diagnostic tests and notify the state's animal health official."
Treatment options for horses with EHV-1 include anti-inflammatory medications, supportive care, and antiviral therapies in certain cases. Vaccines are available to protect horses against the respiratory and reproductive forms of the virus, but unfortunately, there is no vaccine to prevent the neurological form, according to LSU Vet Med.
This outbreak serves as a stark reminder of the importance of vigilance and proactive measures in the equine community. As we navigate this challenging situation, it's crucial to stay informed, follow veterinary guidance, and prioritize the health and well-being of our equine companions.
