ODA Implements Rules to Help Prevent the Spread of Equine Herpesvirus

The Oregon Department of Agriculture (ODA) has issued temporary rules to help reduce the risk of spreading Equine Herpes Virus (EHV)/Equine Herpes Myeloencephalopathy (EMH). The rules filed on November 19, 2025, will immediately strengthen Oregon’s ability to prevent the entry and spread of EHV/EHM by requiring additional safeguards for horses entering the state or attending high-risk events.  

ODA was recently made aware of an outbreak of EHV/EHM in horses that were at or associated with barrel racing and rodeo-type events in Texas and Oklahoma. Several cases of EHV/EHM have been confirmed in Texas and Oklahoma associated with these equine events, with numerous reports of additional cases and equine deaths pending investigation.  

Oregon currently has no confirmed cases of EHV/EHM. ODA is coordinating with the affected states to quarantine any horses that have returned to Oregon after being exposed at the Texas and Oklahoma events.  

Rules Overview

• All exhibitions where equines will be present must register with ODA at least 20 days before the event.  
• Specific records must be collected at the time of entry.
• At least one designated veterinarian is involved in planning the exhibition and is available to provide care.  
• Each exhibition where equines are present must have a designated isolation area.

Exhibition requirements and registration

Filed rules: Rulemaking at ODA

About Equine Herpes Virus 

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 through contaminated hands and clothing.  Owners should watch for signs and symptoms and practice biosecurity measures. Good biosecurity practices include thorough cleaning and disinfection of surfaces and equipment that come into contact with affected horses, and individuals who treat or come into contact with infected horses must follow appropriate disinfection protocols when handling multiple horses.

FAQ

Below is a list commonly asked questions and answers regarding the implementation of the temporary rules filed on November 19, 2025 to mitigate the spread of Equine Herpesvirus (EHV). These emergency rules establish specific mitigation steps to prevent the introduction of EHV into exhibitions by horses or other equine species, as well as reduce the risk of transmission of EHV at exhibitions.

Q: We heard the ODA is cancelling all equine events until May 2026. Is that true?

A: No. The ODA is not cancelling any equine events. The intent of the emergency rules is to provide our office with a record of the event and ensure exhibitor information is being collected by the event organizers. This is being done so that in the event of an outbreak we can perform necessary tracebacks to help minimize the spread of EHV. Taking these actions early, before an outbreak occurs in Oregon will allow ODA to rapidly trace any exposure that may occur, while minimizing the impact on the equine industry as a whole.

Q: The event is less than 20 days away. Are we exempt from needing to register?

A: No. If your event is less than 20 days, submit your registration right away. As long as you can complete the registration and meet all of the regulations, the event can still be held if you choose.

Q: We host practices at our arena. Do we need to register and if so, do we need to submit a registration for every practice?

A: No. Per the mandate, an exhibition is defined as an event where livestock from two or more persons are brought together for the purpose of judging, competition, performance or display. Practices, trainings, open rides, and trail rides do not meet this definition and therefore do not need to be registered.

Q: What do you mean we need an isolation area? Can the isolation area be a horse trailer?

A: Each exhibition needs to have a designated area, away from the other horses, where a horse suspected of being ill can be moved. If there are no stalls or corals at the event, you can isolate a horse to their own trailer, but they need to be moved away from other horses, and the veterinarian of record needs to be contacted.

Q: Does the veterinarian of record need to be on site?

A: The veterinarian of record does not need to be on site during the event. The emergency rules requires that event organizers consult a veterinarian in the planning of the event, and that veterinarian (or multiple veterinarians) agree to be on call for the duration of the exhibition. In the event multiple veterinarians are used, particularly for extended events, at least one veterinarian must be available each day of the event.

Q: Will the ODA be checking our records? Do we need to follow up with owners after the event?

A: No. The exhibition is required to maintain the required documentation for 90 days after the completion of the exhibition, but they are not required to do any follow up with owners or submit those records to ODA. In the event that an animal that participated in the event may later test positive for EHV, ODA would contact the event organizers to obtain the records needed to determine exposures that may have occurred at the event.

Q: Why are the emergency rules put in place for so long? They are longer than other states.

A: In Oregon, emergency orders are filed as emergency temporary rules, which are limited to a maximum of 6 months duration. This does not necessarily mean it will last that long, but 6 months is a predetermined duration of those rules. If the need for the rules ends before the 6 month timeline, they will be repealed at that time.

Q: I have heard that there are positive EHV horses in the state of Oregon. Is that true?

A: While we recognize that information is changing fast and sometimes it can be hard to tell what is a rumor and what is fact, as of 12:00PM on November 24, 2025 there are currently no confirmed cases of EHV in the state of Oregon. If any cases of EHV are confirmed in Oregon they will be promptly announced, posted to the ODA Equine Herpesvirus (EHV) information webpage (see link below), and shared with the Equine Disease Communication Center (EDCC).

On November 22, 2025, the Oregon Department of Agriculture was notified by a private veterinarian of a horse exhibiting neurologic symptoms that was boarded at a large boarding facility in Lane County, Oregon. Due to the size and complexities of the facility Oregon State Veterinarian, Dr. Ryan Scholz, responded to the facility Saturday afternoon. The private veterinarian and Dr. Scholz agreed that based on the clinical presentation of the horse and the history of the horse, Equine Herpesvirus 1 (EHV-1) was unlikely to be the cause of the neurologic symptoms.  

Out of an abundance of caution, samples were collected from the horse and submitted to the Oregon Veterinary Diagnostic Laboratory at Oregon State University (OVDL) for EHV-1 testing, and an official quarantine was issued by Dr. Scholz for the facility where the horse was located. Based on Dr. Scholz’s on-site assessment and a review of facility records, it was determined that the exposure risk was limited to the physical portion of the property where the horse was located.  

Testing conducted November 24, 2025 by the OVDL did not detect EHV-1 virus in any sample submitted from this horse, and the quarantine was subsequently released. The Oregon Department of Agriculture would like to acknowledge and thank the private veterinarian, and the affected facility for their quick response and extensive cooperation in responding to this case.