A horse has tested positive for West Nile Virus (WNV) in the South West Corner of SK (near Ponteix, SK), in August 2016. West Nile Virus in horses is a notifiable disease in Saskatchewan. If your clinic diagnoses a case of WNV it must be reported within 24 hours to the Provincial Chief Veterinary Officer, Dr Betty Althouse (306)787-5547.

The following summary of the disease is from the Government of Saskatchewan website:

In horses, West Nile Virus causes an encephalomyelitis, or brain and spinal cord infection. Most horses bitten by a mosquito infected with West Nile Virus will not develop clinical disease. They develop an asymptomatic infection, eliminate the virus and are none the worse for it. For those that do become sick, clinical signs may include, but are not limited to:

  • Listlessness 
  • Weakness of limbs 
  • Inability to swallow 
  • Loss of appetite
  • Depression
  • Muscle twitching
  • Inability to stand
  • Stumbling
  • Lack of coordination
  • Fever
  • Death

These signs may be confused with other nervous system disorders in horses such as rabies, sleeping sickness, equine herpes virus and tetanus. There is no specific treatment for horses affected with West Nile Virus. Just over one third of horses showing clinical disease may die or have to be euthanized because of complications. Sometimes horses that do recover may still exhibit permanent neurological symptoms.

Since West Nile Virus is transmitted by mosquitoes, insect control is important. The species of mosquito responsible for West Nile Virus infection breeds in small, warm, still puddles of water. These puddles of water include those found in poorly drained eaves troughs, bird baths, discarded rubber tires and even hoof prints formed in mud. Removal of stagnant water and tall vegetation as well as the use of insect sprays and repellents are some preventative measures that can be taken. In addition, there are approved vaccines that can protect horses against West Nile Virus infection. Horse owners should contact their veterinarian for information about the vaccines available and to receive recommendations on a disease prevention program.