Wisconsin Reports first Equine WNV Case of 2014

Wisconsin Reports first Equine WNV Case of 2014

A viral disease, WNV is transmitted to horses by infected mosquitoes.

Photo: Photos.com

An unvaccinated St. Croix County mare is the first in Wisconsin to contract West Nile virus (WNV) in that state this year, prompting officials to reminder to horse owners to vaccinate their animals against the virus and Eastern equine encephalitis (EEE). The affected 4 ½-year-old Quarter Horse is recovering after being treated by a veterinarian.

"The cooler, wetter spring delayed a mosquito outbreak in parts of the state, but now that things are heating up it creates the perfect breeding environment for mosquitoes,” said state veterinarian Paul McGraw, DVM of the Wisconsin Department of Agriculture, Trade and Consumer Protection. “Cases of EEE have now emerged in southern states and now WNV has been detected in a horse in Wisconsin."

West Nile and EEE have stricken hundreds of horses in Wisconsin since 2001.

Horses require two doses of the vaccination initially, and then boosters at least annually. "We recommend working with your veterinarian, so you get the best plan for your horse and advice about additional boosters later in the season," McGraw said.

Health Alert: West Nile Virus

A viral disease, WNV is transmitted to horses by infected mosquitoes. 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 drowsiness; propulsive walking (driving or pushing forward, often without control); and "spinal" signs, including asymmetrical weakness. Some horses show asymmetrical or symmetrical ataxia (incoordination). Equine mortality rate can be as high as 30-40%.

Like WNV, EEE is a viral disease that affects the central nervous system and is transmitted to horses by infected mosquitoes. Clinical signs of EEE include moderate to high fever, depression, lack of appetite, cranial nerve deficits (facial paralysis, tongue weakness, difficulty swallowing), behavioral changes (aggression, self-mutilation, or drowsiness), gait abnormalities, or severe central nervous system signs, such as head-pressing, circling, blindness, and seizures. The course of EEE can be swift, with death occurring two to three days after onset of clinical signs despite intensive care; fatality rates reach 75-80% among horses. Horses that survive might have long-lasting impairments and neurologic problems.

While humans can become infected by both WNV and EEE, it does not pass between people and horses. Mosquitoes biting warm-blooded animals is the only method of transmission.

Besides vaccination, McGraw recommends taking other steps to limit horse exposure to mosquitoes. For example, reduce or eliminate sources of stagnant or standing water, remove muck from areas near the horses, stable horses during peak mosquito periods (i.e., dawn and dusk), use equine-approved mosquito repellants, place fans inside barns or stalls to maintain air movement, keep weeds and grass trimmed, and avoid using incandescent bulbs inside stables at night. Instead, place incandescent bulbs away from the stables to attract mosquitoes to areas away from horses.

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