West Nile Virus: To Vaccinate or Not, That Is the Question

Let’s begin with the history of West Nile Virus vaccine. While its safety and effectiveness were at one time questioned, it is now an accepted part of preventative maintenance programs. And although once available only from a veterinarian, the vaccine is now sold through retail outlets.

The good news is that healthy horses are not susceptible to West Nile Virus. In fact, your horse may have been infected and you didn’t even notice. Perhaps you detected some lethargy around the barn or the horse was a little off on the trail, and then returned to its usual self in a few days. In otherwise healthy horses, a light fever is likely the most common course of the disease.

Before automatically reaching for the needle, take time to understand the virus. For starters, do your part to control mosquitoes. And secondly, only vaccinate those at risk for West Nile Virus – young, old and debilitated horses are most susceptible. Since vaccines work by insulting the immune system, do not inject sick animals. Their defenses are already lagging and any vaccine will only depress their immune systems further.

Although the vaccines promise year-long immunity, booster your horse six weeks prior to the onset of mosquito season in your area. Since mosquito strikes peak in late summer and early fall, the West Nile Virus vaccine isn’t likely as effective when administered in spring. Now is the time to administer the vaccine.

As with any vaccine, there are potential side effects. I’ve seen adverse reactions with all of the West Nile Virus products ranging from the relatively minor (pain and swelling at the injection site) to significantly more serious side effects like anaphylaxis, as well as a mare with personality changes. The most common complaints are fever and swollen lymph nodes. Just last year, one manufacturer did a voluntary recall after reports of systemic reactions and death in horses after using their vaccine. If your horse has a reaction of any kind, it’s important to discontinue the vaccination.

If West Nile Virus vaccination is not for you, consider spending about the same amount of money on immune stimulants. Ask your veterinarian about an intravenous immune stimulant or invest in nutraceuticals like MSM and Ester C. Therapeutic grade essential oils – not those used for aromatic purposes – can also stimulate and protect the immune system. Lavender, orange and pine oils can be applied topically, while citronella, peppermint and eucalyptus oils can be incorporated into a homemade insect repellent.

Ultimately, I believe West Nile Virus vaccines serve a useful purpose – they just aren’t appropriate for every horse. Even though I don’t vaccinate my own, I encourage owners to weigh the pros and cons and make informed decisions. Do not allow a sense of guilt imposed upon you by the pharmaceutical industry replace your own good judgement.

When used correctly, vaccines decrease the severity and duration of disease. However, vaccines do not guarantee protection and may actually give horse owners a false sense of security. That’s because manufacturers often manipulate data to influence veterinarians and use clever advertising to create demand for their products. Lost in the marketing buzz is the fact that healthy horses are capable of fighting disease, and that excessive vaccination is eliminating that ability from the gene pool.

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