The Equine Disease Communication Center (EDCC) has reported that Oklahoma has confirmed three additional cases of West Nile virus (WNV) in horses.

“The Oklahoma Department of Agriculture has confirmed three more WNV positive horses bringing the total up to 12 for 2016,” the EDCC report said.

The new cases include:

• A 6-year-old Quarter Horse gelding from Atoka County, which was vaccinated a couple weeks prior to showing clinical signs;
• A 7-year-old pony mare located in Atoka County, which was also vaccinated a couple weeks before developing clinical signs; and
• An 8-year-old Quarter Horse gelding located in Sequoyah County with an unknown vaccination history.

West Nile is transmitted to horses via bites from infected mosquitoes. Clinical signs for WNV include flulike signs, where the horse seems mildly anorexic and depressed; fine and coarse muscle and skin fasciculations; hyperesthesia (hypersensitivity to touch and sound); changes in mentation (mentality), when horses look like they are daydreaming or "just not with it"; occasional somnolence (drowsiness); propulsive walking (driving or pushing forward, often without control); and "spinal" signs, including asymmetrical weakness. Some horses show asymmetrical or symmetrical ataxia. Equine mortality rate can be as high as 30-40%