Commercially available vaccines effectively cross-protect against all the cur- rent strains of parvo, including variant strains. The MLV vaccine is much more effective than a killed vaccine in that it produces a faster and stronger immune response.
Because the age at which individual pups can respond to parvovirus vaccination varies, AAHA 2006 guidelines are to give the vaccine at 6 to 8 weeks of age, then every three to four weeks until the dog is 12 to 14 weeks of age, but many veterinarians prefer to wait until a puppy is 7 or 8 weeks of age to start parvo vaccinations and conclude them at 16 weeks.
High titer–low passage vaccines are more effective than older vaccines, even in the presence of maternal antibodies, and have narrowed the window of susceptibility that occurs between declining levels of maternal antibodies and acquired immunity produced by the vaccine. This has resulted in fewer vaccine failures.
Even after a pup has received his first series of vaccinations, he should not be exposed to dogs who may be a source of infection until after he receives his final vaccination at 16 weeks of age. Boosters are recommended every three years to maintain immunity, following an initial booster at one year. This interval may be increased with further research on vaccine efficacy.
In unvaccinated dogs older than 16 weeks, give two doses of vaccine two weeks apart. Brood bitches should be vaccinated two to four weeks before breeding to ensure high levels of antibodies in their colostrum. Some veterinarians believe this booster is unnecessary.