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Last year, almost 1,000 horses tested positive for West Nile Virus in Minnesota. Thirty percent of those animals died from the disease, which is why the Minnesota Board of Animal Health is urging horse owners to contact their local veterinarian to have their horses vaccinated against the virus.

State veterinarian Bill Hartmann said horse owners should consult their veterinarian to verify their animals are properly vaccinated.

"It's important to start vaccinating horses now so that they have full immunity when the first mosquitoes appear," Hartmann said. "This is especially important if the horse is receiving the vaccine for the first time, because the first vaccination must be given in two doses, three to six weeks apart."

West Nile virus can cause encephalitis in horses, an inflammation of the brain and spinal cord. Birds serve as the host for the virus, which is spread by mosquitoes to other birds and susceptible animals such as horses and humans.

Neither humans nor horses can spread the disease.

Horse owners should contact their veterinarian if they notice any signs of the disease, which include loss of appetite, lethargy, hindquarter weakness, involuntary muscle contractions, loss of coordination, head tilt, convulsions, paralysis, and coma. Whenever signs of a central nervous system disease are seen in a horse, rabies should also be considered. If a horse dies of a central nervous system disease, the brain should be submitted for rabies testing, even if West Nile Virus infection is suspected.

"Horse owners can act now to reduce the risk during peak mosquito season, which usually spans from mid-July through mid-September," said Hartmann. "Based on what we saw last year, very few horses that were correctly vaccinated developed the disease."

Horse owners can also try to reduce the mosquito population around their horses by taking the following steps: eliminate "mosquito zones" by mowing long grass, draining stagnant water puddles, and removing items such as old tires and tin cans that can serve as breeding grounds for mosquitoes; change water in drinking troughs weekly to prevent mosquito breeding; andminimize horses' exposure by using repellents and screens in stables.

State animal health officials will be tracking all West Nile Virus cases in horses in the state. Any case of West Nile Virus in horses, along with all central nervous system diseases, must be reported to the Minnesota Board of Animal Health at 651-296-2942.

Additional West Nile Virus information is available by contacting your local veterinarian or by logging on to the Board of Animal Health's website at www.bah.state. mn.us/diseases/wnv/wnv.htm.