First 2019 equine cases of West Nile virus are confirmed in Colorado


August 29, 2019
Veterinarians and Livestock Owners Contact:  Colorado State Veterinarian’s Office, 303-869-9130
Media Contact:  Mary Peck, 303-869-9005,



Broomfield, Colo. -  The Colorado Department of Agriculture has confirmed that a total of three horses residing on seperate locations in Larimer, Pueblo and Weld Counties have been diagnosed with West Nile virus (WNV). The three cases are Colorado's first confirmed cases of WNV in horses in 2019.  These index cases were diagnosed by Colorado State University’s Veterinary Diagnostic Laboratory in Fort Collins in late August, 2019.

Vaccines in horses have proven to be a very effective prevention tool for WNV, and horses that have been vaccinated in past years do need an annual booster.  If a horse has not been vaccinated in previous years, it will need the two-shot vaccination series within a three to four week period. 

In addition to vaccinations as a preventative measure, horse owners should also reduce local mosquito populations and their possible breeding areas. Recommendations include removing stagnant water sources, keeping animals inside during the bugs’ feeding times, which are typically early in the morning and evening, and using mosquito repellents.

Neurologic Horses and Reportable Diseases:

Any time a horse displays signs consistent with neurologic disease, a complete neurologic examination is warranted. Unless clinical presentation, epidemiologic links, or exposure is definitive for a non-reportable disease, always consider it to be a reportable disease and notify the Colorado State Veterinarian's Office. 
A complete chart of reportable animal diseases in Colorado can be found on the CDA website.