A 3-year-old miniature horse in Pine City was confirmed on July 27 to have West Nile Virus. This marks the first equine case in Minnesota in 2018.
The attending veterinarian reported to the Minnesota Board of Animal Health that the stallion presented with acute neurologic signs, exhibiting profound weakness in his front limbs, tripping and falling and requiring assistance to stand. The horse has no documented history of vaccination against West Nile Virus and is currently receiving supportive care. A mare and a foal also live on the property and are healthy at this time.
“This case is an unfortunate reminder of why it is so important that owners vaccinate their horses against this disease,” said Equine Program Manager Courtney Wheeler.
The last confirmed case of West Nile Virus in a Minnesota horse was November 2017. Last year, 39 states reported 307 equine cases of West Nile Virus. The Minnesota Department of Health has documented two human cases in 2018 to date.
West Nile Virus is a zoonotic disease spread by mosquitoes and thought to cycle between mosquitoes and birds. Mosquitoes contract the virus from birds and then spread it to mammals (and reptiles), most commonly humans and horses. Infected horses can become anorexic, depressed and show neurologic signs or behavior changes. The incubation period in horses is three to 15 days. Many infected horses are asymptomatic. Clinical signs can be similar to those seen with other neurologic diseases, including rabies.
Horse vaccines are available and have been used extensively, contributing to the decline in the number of affected horses. Additionally, disease risk can be reduced by limiting exposure to mosquitoes. This can be accomplished by changing horses’ drinking water regularly, mowing tall grass, draining stagnant water, maintaining screens, installing fans at horse stables and using insect repellants on both horses and people. Also, mosquitoes primarily feed at dawn and dusk, and keeping horses indoors during these times can reduce risk.