Iowa's First Two Equine WNV Cases of 2012 Confirmed

Two Iowa horses have tested positive for West Nile virus (WNV), according to a surveillance report from the Iowa Department of Public Health.

The report issued Monday (Aug. 6) indicates both horses resided in Johnson County, located in the eastern part of the state. A report from the Kalona News indicated both affected horses were euthanized.

Clinical signs for WNV include flulike signs, where the horse seems mildly anorexic and depressed; fine and coarse muscle and skin fasciculations (twitching); 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 (incoordination on one or both sides, respectively). Equine mortality rate can be as high as 30-40%.

The USDA Animal and Plant Health Inspection Service reported 83 cases of WNV in U.S. horses in 2011, with just one of those cases being identified in Iowa.

Horse owners can take several steps to protect their charges from contracting WNV, one of which is vaccination against the disease. The American Association of Equine Practitioners (AAEP) considers the WNV inoculation a core vaccine and recommends horses be vaccinated annually. The AAEP's complete WNV vaccination guidelines are available online.

Other preventive measures include reducing horses' exposure to mosquitoes by:

  • Reducing or eliminating stagnant or standing water sources, which can serve as mosquito breeding grounds;
  • Removing manure from areas near the horses;
  • Stabling horses during peak mosquito periods (i.e., dawn and dusk);
  • Using equine-approved mosquito repellants, and if additional protection is desired, consider using fly masks, sheets, and/or leg wraps;
  • Placing fans inside the barns or stalls to maintain air movement as mosquitoes don't fly well in wind;
  • Avoiding use of incandescent blubs inside stables at night, which attract mosquitoes; and
  • Discouraging wild birds--which can harbor WNV--from roosting near or in your stables.

If a horse is suspected of having WNV, contact a veterinarian immediately to begin treatment.

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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