Seventh Equine WNV Case of 2017 Confirmed in Idaho

Seventh Equine WNV Case of 2017 Confirmed in Idaho

Photo: Gbohne/Wikimedia Commons

Idaho has reported its seventh confirmed case of West Nile virus (WNV) in horses in that state, the Equine Disease Communication Center (EDCC) announced Oct. 10.

The Idaho Department of Agriculture said the yearling Quarter Horse filly with no vaccination history began showing signs of disease on Sept. 16, the EDCC said; clinical signs included facial nerve deficits and ataxia (incoordination) in all four limbs. The EDCC said the filly is responding to treatment.

West Nile is also 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 fasciculation; 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. There are no specific treatments for WNV, however supportive care can help horses recover in some cases. Equine mortality rate can be as high as 30-40%.

Health Alert: West Nile Virus

Vaccines have proven to be a very effective prevention tool for both EEE and WNV. Horses that have been vaccinated in past years will need an annual booster shot; in areas with a prolonged mosquito season, veterinarians might recommend two boosters annually—one in the spring and another in the fall. However, if an owner did not vaccinate their animal in previous years, the horse will need the two-shot vaccination series within a three- to six-week period.

In addition to vaccinations, horse owners also need to reduce the 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 applying mosquito repellents approved for equine use.

About the Author

Erica Larson, News Editor

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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