Act Now to Protect Your Horses from Diseases Carried by Mosquitoes

As spring begins, Treasure Valley horse owners should take action to protect their animals from mosquitoes, and the diseases that they carry, including West Nile virus (WNv). “WNv is present annually in Southwest Idaho and it is important for residents to take steps to protect themselves and their horses from vector borne diseases,” said Jim Lunders, Director of the Canyon County Mosquito Abatement District.

Lunders explained that horses are particularly susceptible to WNv as they have no protection from mosquito bites other than what is provided by their owners. “A horse in a stall or pasture can’t go inside or put on insect repellant when bothered by mosquitoes,” said Lunders. “Horse owners have a responsibility to minimize their exposure to mosquito bites and properly vaccinate them against WNv, Western Equine Encephalitis (WEE) and other diseases.”

“WNv vaccination continues to be an essential preventive measure and should be given annually to provide an adequate level of protection from the virus,” said Idaho State Veterinarian Dr. Scott Leibsle. “Nearly 98 percent of horses that test positive for WNv are non-vaccinated or under-vaccinated. Horse owners should speak with their veterinarians about the WNv vaccination and other annual core vaccinations as well as how to follow an annual booster schedule. Horses that have been vaccinated for WNv in previous years MUST receive an annual booster; a one-time vaccination is not enough.”

It is recommended that an unvaccinated horse receive its first dose of vaccine by April 30, to be properly protected from WNv & WEE.

In addition to vaccination, it is extremely important to take steps to reduce mosquito production in the area immediately around your horse. It is common for mosquito larva to be found in water troughs or stock tanks, “It is unfortunate, but many horses are sickened by mosquitoes likely raised in their own pens” said Lunders “all stock tanks should be stocked with mosquitofish or treated with BTI or Methoprene if they cannot be drained and cleaned weekly.”

“With the onset of Spring and warmer temperatures, we encourage people to take appropriate precautions to protect themselves and their animals from mosquitoes and the diseases they carry,” said Lunders.

He offered the following suggestions to reduce you and your animals’ risk:

  • Vaccinate horses for WNv, WEE, and other diseases.
  • Use EPA registered residual insect sprays on horses, making sure to follow the directions on the container.
  • Have your livestock watering troughs stocked with mosquitofish for free by submitting a service request to CCMAD.
  • Eliminate or treat all sources of standing water that can be a breeding ground for biting mosquitoes, such as: flooded fields, birdbaths, wading & swimming pools not in use, clogged gutters and old tires.

If it holds water for 7 days, it can produce mosquitoes.

  • Wear repellents while outdoors at dusk and dawn when mosquitoes are most active.
  • Wear long-sleeved shirts and long pants when in mosquito-infested areas.
  • Use mosquito repellents containing DEET, Oil of Lemon Eucalyptus, Picaridin or 2-undecanone, making sure to follow the directions on the container.
  • Make sure all screen doors and windows are in good repair and fit tightly.

Additional information on mosquitoes and the diseases they carry can be found at:

Idaho Department of Health and Welfare —

U.S. Centers for Disease Control and Prevention —

American Mosquito Control Association —

Points of Contact: James J. Lunders, District Director Canyon County Mosquito Abatement District; 208-461-8633;

Scott R. Leibsle, DVM, DABVP, State Veterinarian, Idaho State Department of Agriculture; 208-332-8540;