Saint Paul, Minn - A 3-year-old Quarter Horse filly in Wadena County tested positive for West Nile virus (WNV) last week. A veterinarian was called to examine the horse on August 19^th because it was unable to stand on its rear legs. The filly did not have an elevated temperature and was eating and drinking while down. The veterinarian decided to collect samples for WNV testing and provided supportive care to the horse. Test results were returned on August 26^th confirming a WNV diagnosis. The affected horse was not current on WNV vaccinations. An additional 15 horses reside on site and those not current on WNV vaccinations are being given boosters.

“The affected horse appears to be recovering from the disease at this time, which is good to see since it was not current on its vaccination boosters,” said Dr. Brian Hoefs, Senior Veterinarian of the Equine Program. “Horse owners should work with their veterinarian on a routine vaccination program to reduce the risk of these preventable diseases and increase the animal’s chances of recovering fully if they’re infected.”

West Nile virus is regularly found in the U.S. and birds serve as the primary host of the disease. The virus circulates between infected birds and mosquitoes. Once infected, the mosquitoes can transmit the virus to horses or people. The virus can cause encephalitis, an inflammation of the brain and spinal cord. Infected horses may or may not show neurological symptoms and may recover completely, especially those who have a history of annual vaccination.

Vaccines for horses are widely available and have been proven to be effective in preventing infection. Steps can also be taken to reduce disease risk by reducing mosquitoes:

• Change water in drinking troughs every week.
• Mow long grass.
• Drain stagnant water puddles.
• Remove items mosquitoes use for breeding grounds, like old tires and tin cans.
• Place and maintain screens over windows and stable doors.
• Use mosquito repellents to protect horses and people from mosquito bites.

This is a high-risk time of year for West Nile virus transmission. Non-negative test results for West Nile virus disease must be reported to the Board of Animal Health.

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