Three Michigan Horses Test Positive for WNV

Three Michigan Horses Test Positive for WNV

West Nile is transmitted to horses via bites from infected mosquitoes.

Photo: Thinkstock

The Michigan Department of Agriculture and Rural Development (MDARD) reported July 28 that three horses in that state have tested positive for West Nile virus (WNV).

In a statement on its Facebook page, the department said the positive horses included:

  • A 31-year-old Arabian mare from Jackson County;
  • An 8-year-old Arabian gelding from Livingston County; and
  • A 15-year-old Standardbred gelding from Missaukee County.

“All three horses developed severe neurologic signs and were euthanized,” the MDARD statement said.

The Equine Disease Communication Center reported July 29 that the horses’ vaccination statuses were unknown.

Health Alert: West Nile Virus

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 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. Equine mortality rate can be as high as 30-40%.

Horse owners should also consult their private practicing veterinarian to determine an appropriate disease prevention plan for their horses. Vaccines have proven to be a very effective prevention tool. Horses that have been vaccinated in past years will need an annual booster shot. 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 using mosquito repellents.

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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