The DHLPP vaccine protects pups and older dogs from distemper, hepatitis, leptospirosis, parainfluenza and parvovirus. But the shots don’t make dogs safe right away. All dogs need a series of two to four injections to provide them with the necessary immunity to these serious and sometimes fatal diseases. It’s essential that owners protect their dogs from possible exposure until the vaccine has had time to take full effect.
Mammal mamas produce a special first milk called colostrum that contains antibodies to protect newborns from disease. In short time, the immunity the colostrum provides weakens; leaving the babies vulnerable to illness. The rate at which the colostrum wears off varies, and a vet can't know exactly when. So vets administer the vaccine multiple times to ensure it "takes." Since the colostrum counteracts the vaccine when the colostrum's in effect, vaccinations won’t do any good until the colostrum wears. Additional boosters strengthen their immune systems against disease.
DHLPP immunity cannot take over until the puppy’s original immunity is gone. Once it is, he’ll still need some time to make sure he’s got all the protection he needs. According to the Santa Barbara Humane Society, your pup should be fully protected about seven days after his final shot. If you’ve adopted an older dog and aren’t sure of his vaccination history, allow a week after his booster shot to give the vaccine time to take effect.