EHV Outbreak in Southwest USA

Equine Herpesvirus Myeloencephalopathy Outbreak Among Barrel Racing, Rodeo Events in Texas, Oklahoma, No Cases Reported Involving US Federation Disciplines

An outbreak of Equine Herpesvirus Myeloencephalopathy has been found to have been associated with barrel racing and rodeo-style events in Texas and Oklahoma but no cases have been reported of horses involved in dressage, jumping or other U.S. federation disciplines. No restrictions are required so far at events operated by U.S. federation groups.

The Equine Disease Communication Center reported Friday that positive EHM cases have been confirmed with seven horses in Texas, three in both Oklahoma and Louisiana and one each in Colorado and New Mexico. One positive case of Equine Herpes Virus with no neurologic signs was also reported in Oklahoma.

The outbreak caused by equine herpesvirus-1 follows the Women’s Professional Rodeo Association world finals and Elite Barrel Race event Nov. 5-9.

The U.S. federation said that while EHM “is a serious disease, the majority of cases are not fatal. In most outbreaks of EHM, 60-70% of affected horses recover with treatment and supportive care.”

As of Friday Nov. 21, current identified cases have been in the barrel racing/women’s professional rodeo subpopulation of horses.

“Currently, there have been no links or association with USEF events,” the federation said. “Thus, at this time, we support the continuation of USEF events with the implementation of biosecurity procedures in place. However, this outbreak serves as a reminder of the potential disease risks associated with large commingling equine events. It underscores the importance of biosecurity.”

It recommended that all USEF competitions comply with USEF EHV-1 and influenza vaccination requirement, twice daily temperature taking and recording, immediate reporting of a febrile horse (temperature over 101.5F/38.61C), report any clinical signs to veterinarian, avoid sharing equipment without cleaning and disinfecting between uses, limit horse to horse contact, restrict human contact with horses to essential personnel and properly clean and disinfect horse trailers between loads.

“This is an ongoing investigation with several states tracing potentially exposed horses,” it said. “There are likely to be additional cases confirmed across the United States.”