The Oregon Department of Agriculture (ODA) has put temporary rules in place to address the risk of Equine Herpes Virus (EHV) and Equine Herpes Myeloencephalopathy (EHM). These measures, filed on November 19, 2025, are designed to prevent the introduction and spread of EHV/EHM by requiring new precautions for horses entering Oregon or participating in events considered high-risk.
The ODA responded after learning about an outbreak connected to barrel racing and rodeo-type events. Multiple cases have been confirmed in Texas and Oklahoma among horses involved in these activities. There are additional reports under investigation, including equine deaths related to the virus.
At this time, there are no confirmed EHV/EHM cases in Oregon. The ODA is working with officials from Texas and Oklahoma to ensure that any horses returning to Oregon after attending those events are quarantined.
Under the new rules, all exhibitions where equines will be present must register with the ODA at least 20 days before the event. Organizers must collect specific records when animals arrive, involve a designated veterinarian in planning who can provide care during the event, and set up a designated isolation area for potentially affected animals.
According to information provided by the ODA: “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.”
The ODA continues coordinating efforts with other states while providing guidance on preventive actions for horse owners.
