Just a few years ago, West Nile swept across the United States.  The disease was one of the most dramatic epidemics that U.S. veterinarians had to face.  The disease was responsible for the deaths of thousands of horses and a few humans as well.  There are several myths that spread about the disease due to people misinterpreting the news and online chat conversations.  When Fort Dodge came out with a vaccine, there was even talk of the vaccine being dangerous and being responsible for the deaths of horses as well.  Well, here is some information that dispels a few of those myths:

Myth #1: The vaccine is not safe, so why would I chance it on my horses?

This was the first rumor about the West Nile Vaccine.  There were reports of abortions and deformed foals from vaccinated mares.  There were also reports of horses dieing from the disease after they had received the vaccine. The fact is that the drugs were tested by several universities and were deemed to be incredibly safe.  Both the Fort Dodge vaccine and the Merial vaccine are both safe for use on horses and any deaths of horses by West Nile corresponding with the vaccine simply means that the horses were already infected.  If the horse was infected prior to the vaccine, there is nothing the vaccine can do for your infected horse.  The incubation period of West Nile in horses is three to fifteen days.

Myth #2: West Nile is no longer prevalent, so I no longer need to vaccinate my horse.

The number of cases has decreased dramatically, but that is no reason to stop vaccinating your horses.  The fact is that there are horses who are now carriers of the disease, but they do not show symptoms.  They may begin to show symptoms or they may never show symptoms.  The American Association of Equine Practitioners recommends that horses are vaccinated yearly and especially those with higher risks in areas with long mosquito seasons.

Myth #3: My horse was vaccinated last year, so he is protected

There is evidence that horses that were vaccinated a year ago may be more likely to survive West Nile Virus now, but the horse is not protected from the virus without annual vaccinations.  They may be able to contract a diminished version of the disease and since the disease is a virus, there is not cure for the disease.  You can only treat the symptoms and if the horse develops the neurological symptoms, it is likely that they won’t survive.

Myth #4: The vaccination for equine encephalitis is also carried by mosquitoes, so my horse is protected from West Nile Virus also.

Although mosquitoes carry both diseases, the diseases are very different.  The vaccines for encephalitis do not protect your horse from West Nile and your West Nile vaccine does not protect your horse from encephalitis.

To prevent you or your horses from contracting West Nile Virus, you should take measures to protect you both.  Remove all sources of stagnant water, as this is where mosquitoes lay their larva.  Dump out any buckets of water, tires, troughs that have water and are not being used.  Clean water troughs and buckets at least once a month during the summer mosquito season.  Keep your horses indoors during dusk and dawn and screen your stalls or install fans to deter mosquitoes.  Avoid turning lights on in your barn after dark.  Use insect repellents on you and your horses.  Remove any birds and chickens that are around your horses.