Ok...started a new thread...so the other one wouldn't be thread jacked LOLNatalie: This is a subject for another thread if you want to persue it but booster shots don't really boost anything. You give a series of vaccinations for reasons that have to do with mother's immunity still being in the puppy's body for an undertermined period of time. If you knew the exact moment the mother's immunity was no longer in the puppy's body, one vaccination is all that's needed.
If the mother's immunity is up (vaccinated as an adult), the puppies get her immunity through her milk. When they are weaned from her milk they don't have enough antibodies to stay safe from parvovirus, parainfluenza, hepatitis, and distemper until the age of 16 weeks, or 4 months. So they have to be boostered at 8 weeks (which is usually when puppies are completely off their mother's milk...at least by the choice of the mother LOL) to make sure they have immunity. Then boostered again and 12 weeks, because their immune systems are still not mature and able to produce enough antibodies to sustain immunity. Finally at 4 months their immune systems are mature enough to sustain immunity through adulthood.
That is why it is completely unneccesary for breeders to vaccinate before 8 weeks of age....but still so many do.
Boosters should be given once a month til 4 months of age...so one shot at 8 weeks, one at 12 weeks and the last at 16 weeks.
Puppies not boostered between the ages of 8 weeks to 16 weeks have a great risk to getting things like parvo...I have seen it countless times working at vet clinics. Its a devastating disease that most likely means death for the puppy. If puppies didn't get parvo, etc between these ages it would be worthless to give boosters. And since the parvovirus is a very hardy and is sustained in the environment...found in pretty much any ground soil...even if puppies are kept within their home environment, they are still at risk.
Like I stated in the other thread, this is what I have researched to be the most successful, and have little biased opinion pushed on me by others.