Two Weld County, Colorado farms are under quarantine following identification of equine herpesvirus type 1 (EHV-1) infection. One horse was euthanized after developing equine herpesvirus myeloencephalopathy, a potentially severe neurological disease caused by EHV-1. The other horse is under observation, with no indication of whether it's actually sick.
According to Scott Weese, Large Animal Internal Medicine Specialist at Ontario Veterinary College, both horses attended the National Cutting Horse Association’s Western National Championships in Ogden, Utah.
Whether or not the show is where the horses were first infected is unclear, but any time large numbers of horses are in the same area after being stressed by shipping, competition, management changes and other factors, infectious disease exposure risks rise.
The EHV-1, virus is dormant within a large percentage of healthy horses. Most of the time, infected horses are not shedding the virus, but shedding can occur if horses are stressed or sick.
EHV outbreaks and quarantines seem to be much more commonly reported over the past couple of years. Whether that's because of a true increase in disease or an increase in publicity and response to disease is unclear.
Good general infection control practices to limit the spread of the virus when it is being shed by horses, and prompt identification and isolation of horses with EHV infection are important but often overlooked control measures.