The hottest debate over current immunization protocols is "Are we vaccinating too much?" This question addresses two issues: first, do we vaccinate too often, and second, do we give too many types of vaccines? Whether to continue vaccinating annually may be the greatest controversy concerning canine vaccine protocols. Annual vaccine boosters have been a tradition that seemed logical to continue. Scientifically validated studies of current vaccines, however, have not demonstrated the need for annual boosters.

To the contrary, current studies reveal that in most dogs annual vaccine boosters do not significantly increase immunity. Research shows that instead of boosters do not significantly increase immunity. Research shows that instead of boosting immunity, the vaccine viruses can be neutralized by the very immune system they are supposed to stimulate.

Until recently, many vets believed that even if annual vaccinations weren't necessary, they at least weren't harmful. This belief is rapidly falling from favor. Instead, more veterinarians now realize that vaccination should not be considered an innocuous procedure because of the potential for adverse reactions and long-term negative effects.

Adverse reactions are generally uncommon and thought to be more prevalent in certain breeds and specific families, suggesting a genetic predisposition. But, for many reasons, the true number of adverse reactions in dogs is unavailable. The number that is reported to the USDA, the vaccine companies and the U.S. pharmacopeia reporting system is not very high, despite the fact that in 1996 an estimated 65 million does of vaccine were administered to dogs.

Reports reveal that anaphylactic shock, an immediate life-threatening reaction, occurs in approximately one case per 15,000 doses of vaccine given. What has not been clearly identified are the more insidious long-term adverse effects of annual vaccination and what percentage of dogs experience these effects.

Vaccine-induced protection from potentially fatal diseases has always out-weighed what was perceived as a small risk of adverse reaction. But since most dogs attain persistent protective immunity after completing their first year of vaccines, and that annual revaccinations doesn't increase immunity in the majority of dogs, owners and vets much re-evaluate whether the risks outweigh potential benefits.

Despite mounting evidence to decrease the frequency of vaccination protocols remain common practice. One reason is that the vaccine visit provides the opportunity for vets to perform annual physical exams. Many vets believe that unless vaccines are due, owners are less likely to bring their dogs for an annual exam. They argue that the benefits of an annual exam outweigh the potential risks of the vaccines.

Determining how often to vaccinate should be simple; that is, revaccinate whenever the vaccine wears off. If there were an accurate way to measure protective immunity, dogs could be tested annually for their level of protection and be boosted if their levels fell too low. However, no simple tests accurately measure levels of protection. In the debate, the use of antibody titers to assess immunity is frequently suggested. Results of titers only reveal whether body responded to the vaccine and do not reflect immunity.

Vaccine protocols could evolve to an "as needed" basis, if data were available on the duration of immunity induced by vaccination in the majority of the dog population. Unfortunately, the minimum and maximum durations of protection for most canine vaccines are not known. Long-term, vaccine-induced immunity is also being demonstrated in dogs and cats. For example, several studies have demonstrated protection from canine distemper ranging from five to ten years in dogs that were vaccinated only during puppyhood. As in some people, experts expect some dogs not to develop lifelong protection because of inherent defects in the individual's immune system. Keep in mind there is not and never will be any standard answers or consensus on vaccine issues. Each person must learn what they can and seek out the most current information.