West Nile Virus Update

Once again West Nile Virus has been in the news, and people are becoming much more concerned about it. There have been several hundred dead birds found in San Diego County that have been confirmed to have died from West Nile Virus. There have been three confirmed human cases, and one confirmed equine case. The cases of West Nile Virus have also shown up much earlier this year than any other year since the virus arrived in San Diego County.

West Nile Virus is an encephalitis virus which causes swelling of the brain. The clinical signs of West Nile range from mild neurological signs such as muscle tremors, to more severe signs such as poor coordination and decreased mental awareness, or death. West Nile is only spread by mosquitoes and is NOT contagious from horse to horse.


So what does this mean for you and your horse?

1. West Nile virus is here and it is not going away any time soon 2. The best protection for your horse is to get it vaccinated. The good news is that we do have very effective equine vaccines to prevent West Nile Virus. The efficacy of the vaccine is close to 99%. The recommendation from the AAEP (American Association of Equine Practitioners) is as follows.

• Foals born to well vaccinated mares should get their first vaccination at 6 months of age and then a booster 2-4 weeks later, and then be boostered again at 1 year of age.

• Foals born to mares with no vaccine history should get their first vaccination at 2 months of age, booster 2-4 weeks later, and boostered again at 1 year of age

• Pregnant mares should receive a booster 1 month before foaling.

• All other horses should be vaccinated once a year following the initial series.

August through October is the peak season for West Nile Virus in our area, but because of our mild and temperate climate the disease and the risk for infection are present all year long. If your horse has not been vaccinated for West Nile Virus within the last 12 months we would strongly recommend having this done. The cost of getting your horse vaccinated is significantly less than having your horse treated for the disease.


Be safe, but don’t be afraid of West Nile Virus. As long as your horse is vaccinated according to these guidelines it should be protected. If you have any questions about the vaccination status of your horse feel free to contact one of the veterinarians at Creekside at (760) 728-2319.