PrintAn outbreak of equine herpes virus myeloencephalopathy, the neurological form of equine herpes virus (EHV-1), has been reported in eight western U.S. states, prompting the cancellation of 19 U.S. Equestrian Federation competitions.
The outbreak originated at the National Cutting Horse Association Western National Championship in Ogden, Utah, April 29-May 9. As of May 19, the U.S. Department of Agriculture reported 34 confirmed cases and that all of those horses attended the cutting horse event or came into contact with horses that attended the event. Of the 34 confirmed cases, 33 are horses who attended the event. On May 23 the California Department of Food and Agriculture reported another confirmed case of EHM and on May 20 the Utah Department of Agriculture confirmed two additional cases.
Cases have been confirmed in Arizona, California, Colorado, Idaho, New Mexico, Texas, Utah and Washington. Equine Canada reported one confirmed case in Alberta and three suspected cases in British Columbia, and that all of those horses were either at the Utah show or in direct contact with those horses. The USEF has compiled a list of resources for horse owners sorted by state.
According to the May 19 report, seven horses associated with this outbreak are dead or have been humanely destroyed. The Utah Department of Agriculture reported on May 21 that one additional horse under treatment for EHM was euthanized.
The EHV-1 virus is highly contagious and can cause abortion, respiratory disease, neonatal death and neurologic disease in horses.
This outbreak has prompted the cancellation of some equestrian events in affected states, although most are continuing as planned, many with heightened veterinary security measures. In addition to the 19 cancelled competitions, six more have rescheduled as a result of the outbreak. Read about how the outbreak is affecting horsemen in one county in California.
