Think About This .....

 Kirk's Current Veterinary Therapy XI - 205 

                                          "Annual Vaccinations"

                   "A practice that was started many years ago and that lacks
                        scientific validity or verification is annual revaccination.  Almost
                        without exception there is no immunologic requirement for
                        annual revaccination.  Immunity to viruses persists for years or
                        for the life of the animal.  Successful vaccination to most
                        bacterial pathogens produces an immunological memory that
                        remains for years, allowing an animal to develop a protective
                        anamnestic (secondary) response when exposed to virulent
                        organisms.  Only the immune response to toxins requires
                        boosters (e.g. tetanus,,,[ets.]), and no toxin vaccines are]
                        currently used for dogs and cats.  Furthermore, revaccination with
                        most viral vaccines fails to stimulate an anamnestic (secondary)
                        response as a result of interference by existing antibody (similar
                        to maternal antibody interference).  The practice of annual
                        vaccination in our opinion should be considered of questionable
                        efficacy unless it is used as a mechanism to provide an annual
                        physical examination or is required by law (i.e. certain states
                        require annual revaccination for rabies).  

Text Book Used By Veterinary Schools Across the Country, 1993 edition