Vaccination has been called "medicine's greatest triumph," responsible for nearly eradicating childhood killers such as polio and smallpox. Vaccinating your horse protects him against equally frightening diseases, including tetanus and sleeping sickness, both of which are almost always fatal. In the past decade, however, vaccine opponents have raised concerns about vaccinations—and even begun to question whether they're necessary at all.
Should you continue to vaccinate your horse? If so, which vaccines should you give? It's hard to know what's right.
In this article, I'm going to investigate the top five arguments I've heard made against vaccination—in both human and veterinary medicine. While some of the concerns are legitimate, many more are not—and consequences of under-vaccination can be even more frightening than the fears of vaccine opponents.
Once you've heard all sides, I'll give you a set of rational questions to ask to make educated decisions about your own horse's vaccination plan.
Point #1: Vaccines are dangerous. Overheard: "They lead to a hyperstimulated immune system and all kinds of health problems. I've read on the Internet that vac- cination causes headshaking and allergies in horses, too."
Counterpoint: When it comes to horses, there are no legitimate studies that link vaccination to diseases related to an over-stimulated immune system such as allergies or skin disease. The stories you hear are just that—stories. While there may be other reasons to question whether or not to administer a certain vaccine to your horse, this simply isn't one of them.
Point #2: The side effects are awful. Overheard: "OK, so maybe there's no scientific proof that vaccina- tion causes other diseases, but the side effects from vaccines are horrible. Every time my horse gets vaccinated he can't lift up his head for days. Death is even possible."
Counterpoint: Yes, vaccinations can cause side effects—some more than others. And this is clearly a legitimate reason to consider your horse's vaccination program carefully. Some horses are more sensitive to vaccines than others, and if yours is one that seems to have a problem every time he's vaccinated, you may choose to take the minimal-vaccination route. In this situation, the concept of "herd immunity" comes into play: If 80 percent of the population in a herd is vaccinated, the remaining 20 percent have some protection against a serious outbreak.
If your horse is a reactor, you should look at individual vaccines carefully. Vaccines for some diseases are more problematic than others, and different forms of vaccines for the same diseases have different reactivity. Ask your vet to help you decide which vaccines are most important due to exposure risk and severity of disease.
Once you've decided which diseases are most important to target, look at the different forms of each vaccine available. For example, killed-virus vaccines may not be quite as effective as modified-live-virus vaccines, yet they typically cause much less significant reactions. And intranasal vaccines for respiratory diseases are often much less reactive than their intramuscular counterparts.
If you're considering strangles vaccination (a vaccine with high risk for side effects), you can measure antibody levels in the blood prior to vaccinating; if antibody levels are high, your horse is at greater risk for serious side effects (and could be protected anyway), so don't vaccinate.
Finally, if your horse is exceptionally sensitive, ask your vet whether it would be advisable to administer a dose of a non-steroidal anti-inflammatory medication such as flunixin meglumine (Banamine®) prior to vaccination to minimize side effects.
As an example, we have a horse in our practice that's highly reactive to vaccines. He spikes a fever, his legs swell, and he can even act a little colicky afterwards. He lives in a big, busy competition barn, where his exposure risk is high. His vaccination program consists of tetanus—because it's such a safe vaccine against an extremely dangerous disease—and influenza given intranasally, where side effects are extremely rare. He's lucky to live in a barn where the other horses are on a solid vaccination program so herd immunity is high. And he receives a dose of Banamine prior to every tetanus vaccine to minimize his risk of side effects.