Minnesota first 2026 horse West Nile case

The United States — Minnesota Board of Animal Health confirmed the state's first equine case of West Nile virus (WNV) in 2026. The affected animal is an unvaccinated three-year-old standardbred gelding in United States — Polk County, Minnesota. The horse exhibited moderate weakness, loss of muscle coordination, and fell during a neurological exam. Its veterinarian initiated steroid treatment, and the horse began improving within days. Officials, including Dr. Heather Damico, senior veterinarian leading the Board's equine program, noted that late summer is the typical peak of WNV season in Minnesota and that most cases affect unvaccinated or under-vaccinated horses. WNV is transmitted by mosquitoes that acquire the virus from infected birds; infected horses cannot transmit the virus to people or other horses. The virus can cause inflammation of the brain and spinal cord, with severe cases potentially leading to lifelong effects or euthanasia. The Board recommends annual vaccination and environmental management to reduce mosquito breeding sites, such as changing water troughs weekly, mowing grass, draining stagnant water, and removing breeding items. State regulations require reporting of non-negative WNV test results in animals. The United States — Minnesota Department of Health provides guidance for human cases.