West Nile virus confirmed in Kandiyohi County horse

Routine vaccination recommended for all horses

Postmortem test results confirmed Minnesota’s first reported West Nile virus case of 2022 this week. In late July, an unvaccinated 4-year-old Quarter Horse mare from Kandiyohi County was euthanized due to deteriorating neurologic conditions. Tests were ordered to confirm a cause of death and results were positive for West Nile virus. More than 30 other horses are boarded at the same facility and the owner reports they’re all current on their West Nile virus vaccinations and appear healthy at this time. Infected horses cannot spread the virus to people or other horses.

“This is an unfortunate, preventable, outcome from a disease we see pop up pretty much every year around this time,” said Dr. Brian Hoefs, Senior Veterinarian of the Equine Program. “Horse owners and their veterinarians should keep a routine vaccination program, including West Nile virus, to reduce the risk of 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. Infected horses cannot spread the virus to people or other horses. The virus can cause 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.

In addition to vaccinations horse owners can reduce environmental risks of West Nile virus 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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