Causes for Vaccine Failure

Lack of Consistent Protocol
When we examine all of the information about maternal derived antibodies, windows of susceptibility, breed susceptibilities, the possibility of unidentified strains, and the effectiveness of different vaccines, we begin to see why there are so many different vaccination protocols and why some vaccinated animals still develop the disease.

Vaccination protocols have been developed that will help protect the widest range of dogs. In using these protocols, we understand we will be vaccinating some dogs that are not capable of responding and we will be revaccinating some dogs that have already responded and developed a high titer. But without doing an individual test on each puppy, it is impossible to determine where the puppy is in its immune status.

Recommended Protocol

We also realize due to the window of susceptibility, some litters will contract Parvovirus despite being vaccinated. By using quality vaccines and an aggressive vaccination protocol, we can make this window of susceptibility as small as possible. The generally recommended protocol is to vaccinate puppies against Parvovirus beginning at 6-8 weeks of age, and revaccinating every 3 weeks until the puppy is 16-20 weeks of age. A booster is given at 1 year of age and every 1 - 3 years thereafter.

Maternal Antibodies
The primary cause of failure of CPV vaccines is an interfering level of maternal antibody against the CPV. Maternal antibodies are the antibodies present in the mother's milk during the first 24 hours after the puppy's birth. The age at which puppies can effectively be immunized is proportional to the titer of the mother and the effectiveness of transfer of maternal antibody within those first 24 hours. High levels of maternal antibodies present in the puppies' bloodstream will block the effectiveness of a vaccine. When the maternal antibodies drop to a low enough level in the puppy, immunization by a commercial vaccine will work.

Window of Susceptibility
The complicating factor is that there is a period of time from several days to several weeks in which the maternal antibodies are too low to provide protection against the disease, but too high to allow the vaccine to work. This period is called the window of susceptibility. This is the time when despite being vaccinated, a puppy can still contract Parvovirus. The length and timing of the window of susceptibility is different in every puppy in every litter.

Seek Professional Help

Undertaking the treatment of affected dogs and puppies without professional veterinary care is very difficult. Even with the best available care, the mortality of severely infected animals is high. Without the correct amount of properly balanced intravenous fluids, the chance of recovery in a severely stricken animal is very small.