West Nile Virus (WNV) was confirmed on serologic samples from a yearling this week. The yearling had no recent travel or vaccination history. On the morning of 7-26-13, the owner noticed that the yearling was lame in the left hind limb. By the afternoon, the horse was down and paralyzed in the back limbs by the time the veterinarian arrived. The yearling had a temp of 103.5 but was BAR and eating and drinking. Upon initial exam, the veterinarian took samples for EHV-1 and commenced supportive treatment. On 7/27/2013, EHV-1 samples tested negative at which time arboviral testing commenced at the NYS Veterinary Diagnostic Lab. The IgM Capture ELISA for WNV was positive. Fortunately, on 7/27/2013 the owner reported improvement in the yearling. As of 8/82013, the yearling is still alive, is now standing with some residual ataxia in hind legs. There are other horses on the premises but none are showing signs of disease.
To reduce the risk for your horse, be sure to eliminate standing water where mosquitoes breed, excessive mosquito population reduction (bug zapper?) and keep your horse covered or inside at dusk and dawn when Mozzies are active. We use pyrethrin based repellants daily in a wipe on formulation, not spray on. And, lastly if your horse has not had a West Nile Vaccination, it's not too late. Horses that will be traveling outside of NYS this fall might benefit from a booster vaccination about a month prior to travel.