All the vaccinations do the same thing. The reason you get a series is because the first shot given at 8 weeks usually does nothing because the antibodies received from the mother are still pretty high at this time and kill the vaccine before your dog can "fight it" and gain immunity. Only about 5 percent will receive immunity from this vaccine.
The next at 12 weeks, the maternal antibodies will be lower so the vaccine is effective in a higher majority of puppies (like 25% more or so).
The maternal antibodies are usually gone by 16 weeks so this shot is sometimes the last given, but there is research to suggest that a small percentage (like 5% or so) still do not achieve immunity so some vets give another at 20 weeks. At any point you could have a titer test performed which would show if the puppy's body has made immunities against a disease rather than revaccinating.
After giving an "effective" vaccine. It takes about 2 to 3 weeks to produce the antibodies and be protected from the disease so this would be about 20 weeks (after the 16 week shot) for most puppies and although a few might be immune as early as 12 weeks, there will be a few that won't have immunity until 23 weeks (3 weeks after the 20 week vaccine) . I would not give the rabies until the pup is at least 6 months old. I would listen to the vet in this case, better safe than sorry. |