11/20/2025
Over the past couple of days, we and many other large animal clinics have been contacted by numerous horse owners regarding the EHV outbreak at the Texas and Oklahoma rodeo/barrel events. As a result, we have copied and pasted the following information straight from the notification we received from the Mississippi Board of Animal Health:
11-19-25
The Mississippi Board of Animal Health is monitoring an outbreak of Equine Herpes Virus (EHV)/ Equine Herpes Myeloencephalopathy (EHM) in horses that were at or associated with barrel racing and rodeo-type events in Texas and Oklahoma. Several cases of EHM have been confirmed in Texas and Oklahoma with numerous reports of additional cases and equine deaths pending investigation.
We do not have any confirmed cases of EHV/EHM in Mississippi at this time. Our office is coordinating with the affected states, and we are currently awaiting to receive trace information from Texas and Oklahoma. If we receive traces from the other states, we will contact those owners directly to determine the health status of the horse and steps to mitigate further spread of the disease.
This outbreak serves as a reminder of the potential disease risks associated with large equine events where animals comingle and underscores the importance of timely reporting of diseases and ensuring that movement requirements are followed, including veterinary inspection and health certificates prior to travel.
Horse Owners: If your horses traveled to Texas, Oklahoma, or other equine events where EHV exposure may have occurred, please contact our office directly at (601) 359-1170. We will provide guidance regarding isolation and monitoring.
General guidance includes:
● Exposed horses should be isolated for 21 days after last known exposure.
● Appropriate isolation includes restricted access to other horses, avoiding the sharing of equipment or personnel, and utilization of protective barrier precautions.
● Exposed horses should be monitored twice daily for elevated temperature (above 101.5*), respiratory signs (nasal discharge, coughing), and for clinical signs consistent with equine herpes myeloenceophalopathy (neurologic symptoms including inability to stand, difficulty walking, lethargy, and urine dribbling).
● If elevated temperature, respiratory signs, or EHM-compatible clinical signs are noticed, contact your veterinarian.
Upcoming equine events: Equine herpes virus can be shed for prolonged periods of time, including in clinically healthy horses, which increases the risk for continued disease spread during an EHV/EHM outbreak.
● Event Organizers: We recommend you consult with your veterinarian and understand the risks associated with hosting equine events during a multi-state outbreak of EHV/EHM. Cancellation or postponement of events may be important to stop the spread of disease. If events do take place, we recommend health certificates issued within 72 hours of the event and increased biosecurity practices on site.
● Horse Owners: We recommend that you consult with your veterinarian about the risks associated with travel to upcoming equine events. EHV is a common virus and is often present in the environment, so biosecurity measures are extremely important for preventing disease transmission.
Interstate Movement: Due to the multi state outbreak of EHV associated with multiple equine events, the use of EECVI (Extended Equine Certificate of Veterinary Inspection) is currently disabled. Please note that many states may be implementing movement restrictions or new import requirements for equines during this outbreak. Please always check with the state of destination to ensure that you are following current import requirements.
Equine Herpes Virus Information:
EHV‐1 is spread from horse to horse through contact with nasal discharge or spread as aerosol droplets. Infected horses may not show clinical signs of the virus but may still act as carriers. Horses can also contract the virus by coming into contact with contaminated surfaces such as stalls, water, feed, tack, and transport vehicles. People can spread the virus from horse to horse by contaminated hands and clothing. It is important for owners to watch for signs and symptoms and practice strict biosecurity measures. Good biosecurity practices include extensive cleaning and disinfection of surfaces and equipment that come in contact with affected horses, and individuals who treat or come into contact with infected horses need to follow appropriate disinfection protocols when handling multiple horses.
Visit the MBAH website to see the Reportable Disease List. The Mississippi Board of Animal Health State Veterinarian’s Office may be reached any time at (601) 359-1170 or (888) 722-3106.
