11/20/2025
Many of you may have heard of an EHV-1 outbreak in Texas and Oklahoma. Because the initial (index) case occurred following the World Championship Barrel Racing Finals in Waco, TX, many unknowingly exposed horses travelled back to their home states or on to other events, unfortunately potentially allowing the outbreak to become widespread. EHV-1 can have an incubation period of up to 14-21 days.
Please be aware that some states may be cancelling 6 month travel passports or may have stricter than typical import requirements; if you have planned upcoming travel with your horse, you should check with the state of destination for the latest information.
Our state veterinarian made an announcement today with the following information:
The Oregon State Veterinarian’s Office has been made aware of 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 associated with these equine events, with numerous reports of additional cases and equine deaths pending investigation.
We do not have any confirmed cases of EHV/EHM in Oregon 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 and issue quarantine orders to mitigate further spread of the disease.
This outbreak serves as a reminder of the potential disease risks associated with large commingling equine events. It underscores the importance of timely reporting of diseases and ensuring that movement requirements are followed, including veterinary inspection and health certificates prior to travel.
Recommendations for Horse Owners
If you have clients with horses that traveled to Texas, Oklahoma, or other equine events where EHV exposure may have occurred, please contact our office directly at 503-986-4711. We will provide guidance regarding isolation and monitoring:
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, owners should contact their veterinarian.
Upcoming Equine Events
Equine herpes virus can be shed for prolonged periods of time, including in clinically healthy horses, which increases risk for continued disease spread during a EHV/EHM outbreak.
Event Organizers: We recommend event organizers consult with their designated show veterinarian and understand the risks associated with hosting equine events during a multi-state outbreak. Cancellation or postponement of events may be important to stop continued spread of disease. If events do take place, we recommend short-timed health certificates within 72 hours and increasing biosecurity practices on site. Additional requirements for equine exhibitions may be implemented based on risk.
Interstate Movement
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 import restrictions.
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 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.
The Oregon Department of Agriculture State Veterinarian’s Office Disease Reporting Hotline may be reached any time at 503-986-4711.
