You have probably seen at least one article or advertisement condemning vaccinations, claiming they are a severe stress to the horse’s system, more dangerous than we realize, unnecessary, or that they simply don’t work, anyway. This has turned a number of horseowners away from vaccines, while others vaccinate their horses for everything under the sun, albeit often under the direction of their veterinarian. The truth about what vaccinations your horse really needs lies somewhere in between.
There is no doubt that a vaccination has the ability to induce an immune response in the horse without causing a full-blown disease state. Vaccines have historically been the only approach to preventing epidemics of disease, particularly with highly infectious organisms.
The argument that vaccines are unnecessary if the horse is maintained in a perfect state of health can be dispensed with quickly. For one thing, it is virtually impossible to feed the horse all the nutrients he needs for maximum immune function. For another, we don’t really know what all of them are, let alone how much would be needed. Furthermore, even the healthiest horse with a perfect immune system would still be vulnerable. Potentially infectious organisms are constantly evolving and mutating to find ways around the immune system.
Vaccine critics also often state that vaccines don’t work. If we are talking about complete protection from disease, this may be true. Some vaccines only modify the severity of disease, at best, providing no obvious benefit at all if the horse is challenged at a time when other stresses have already weakened his defenses. But even if we accept vaccine protection is less than 100% in some cases, it is still worth doing, since less-severe disease is preferable to a more serious illness.
The real dilemma about vaccines has surfaced in recent debates about risk vs. benefit and how often and with what we vaccinate. Respected experts in hematology and oncology are challenging current vaccination practices.
Clinical medicine and basic research show that combination vaccines, particularly combinations of viral vaccines, may seriously overload the immune system, leaving the animal wide open to all types of other infections, including opportunistic organisms (like the protozoa that cause EPM), while recovering from the vaccine insult.
It is also believed that too-frequent vaccinations can lead to autoimmune (or at least immune-related) problems, such as allergies, skin ailments, frequent infections and possibly even problems in other organs or joints.
It is even theorized that permanent defects in the immune system may result and at least partially account for the increased incidence of immune-system-related cancers, like lymphosarcoma. If these theories are correct, the practice of throwing multiple vaccines at the horse on a yearly basis with the philosophy that “it can’t hurt” needs revision.
The dangers of unnecessary vaccination were first recognized in animals and humans with compromised immune systems, such as inbred dogs and people with AIDS. It is still safe to say that these small groups represent those at greatest risk of having serious consequences from vaccinations.
Autoimmune and immune-deficiency diseases are relatively uncommon in horses so far, at least partially because our horses are not as intensively inbred as many dog breeds. However, the warning signs are there that this is changing (see October 1999 editorial). The other problems — allergies, chronic infections (especially skin and respiratory), susceptibility to opportunistic infections, increased incidence of some forms of cancer — are definitely occurring in horses.
While other factors are operating here, too, not the least of which is the increasing burden of environmental toxins, it makes sense to take a long, hard look at traditional annual vaccination practices.
Serum/blood antibody (IgG) levels against specific diseases may be a better way to gauge frequency of vaccinations than an automatic once-a-year schedule. Immunity to many diseases lasts much longer than a year, especially if the horse had a natural infection.
Some vaccine manufacturers base their recommendations on when antibody levels begin to drop, or drop below an arbitrary level. However, this doesn’t tell the whole story, since any level of antibody in the blood means the immune system is primed and ready to mount a full-scale antibody response if challenged.
The only way to know if the horse really needs a repeat vaccination is to check. This approach won’t save you money, but it may spare your horse an unnecessary vaccination. If you’re interested, speak with your veterinarian about having the testing done. Many large, nationwide blood-testing laboratories offer these types of tests.
Wise Vaccination Guidelines
If we focus on the sensible, valid concerns about over-vaccination and vaccination safety, it’s easy to come up with a reasonable approach to decreasing complications without sacrificing the level of protection against infectious disease:
1. Vaccinate annually only for life-threatening diseases that pose a significant risk for the horse (see our chart).
2. Vaccinate against nonfatal diseases for which the horse is at high risk (see our sidebars and chart) with an initial series as recommended by the manufacturer but thereafter only as risk and blood levels of antibodies dictate (your vet can test for blood levels of antibodies).
3. Vaccinate foals according to blood levels of antibodies.
4. Avoid vaccinating against more than one disease at a time. This includes avoiding single-dose combination vaccines and injections of several different vaccines simultaneously. Schedule needed vaccines at monthly intervals.
5. Avoid vaccinating during periods of stress (weaning, transport, heavy training, change of barns, competition, recent illness or injury, estrus). Stress already places a burden on the immune system.
6. Request vaccines prepared without aluminum adjuvants or mercury-based preservatives.
7. Reduce the need for vaccinations by not exposing your horse unnecessarily to other horses.
8. Improve response to vaccines by maintaining a healthful diet with high levels of natural anti-oxidants.
Recommendations for vaccinating other animals, particularly breeds at high risk of autoimmune type diseases, have changed drastically. More and more equine veterinarians are using a conservative approach in recommending vaccinations. We believe all horses should be vaccinated for the life-threatening diseases for which they are at high risk.
Without doubt, the risk of a serious illness and the need to control outbreaks of disease by vaccination of susceptible horses outweighs any potential risks of the vaccine. However, the exact program that is right for your horse depends on your individual circumstances and is a matter you should discuss in depth with your veterinarian, weighing the risks vs. benefits of each proposed vaccine. There are enough serious questions regarding potential negative health effects of vaccines to warrant a solid look at when, with what and how often we vaccinate our horses.
Also With This Article
Click here to view ”Tetanus And Fresh Wounds.”
Click here to view ”Vaccinating Your Own Horses Can Be Risky.”
Click here to view ”New Flu Vaccine.”
Click here to view ”Horse Journal Guide To Vaccinations.”
Click here to view ”We Say No To Nosodes: Homeopathic Vaccines.”
Click here to view ”Vaccinations For Broodmares.”
Click here to view ”Vaccinations For Performance Horses.”
Click here to view ”Special-Need Vaccines.”
Click here to view ”Vaccinations For Foals.”
Click here to view ”How Vaccines Work.”