West Nile virus has been identified in 2006 in humans and birds, but no horses have tested positive on the Prairies this year.
As of Aug. 23, six human cases have been identified in Alberta, two in Saskatchewan and 17 in Manitoba.
West Nile is a mosquito-borne virus that can cause swelling in the brain and spinal cord in horses, birds and humans.
It is carried by the culex tarsalis mosquito, which is most active in late summer. Mosquitoes spread the virus after feeding on infected birds.
Read Also
The Western Producer Livestock Report: July 17, 2025
U.S. hogs averaged $106.69 on a carcass basis July 11, down from $110.21 July 4.
“The virus in the mosquitoes that carries it is here,” said Curt Hagele, a veterinarian with the Saskatchewan Veterinary Medical Association.
The association recently issued a public service announcement warning horse owners to be aware of the virus that can appear through a variety of symptoms.
Common signs in horses include fever, staggering, twitching of the muscles of the face and neck, depression, excitability, difficulty eating and various degrees of paralysis.
Only a small percentage of horses exposed to the virus develop clinical signs of the disease.
“In the worst case scenario it can kill the animal,” said Hagele.
Vaccinations against West Nile virus are available, but Hagele recommends horse owners talk to their veterinarians about virus risks in their area.
“They’re more aware of the moisture levels and mosquito populations and whether the horse has been vaccinated or if it’s in a stable,” he said.
“It’s more of a local thing.”
In Alberta, 170 horses tested positive in 2003. In 2004, only four horses tested positive and three did last year.
