Human babies get a lot of shots, when they belong to parents who are OK with them getting shots. It’s a controversial issue for both humans and pets. You have to do what feels right to you based on the information you have at hand. For the record, my kids are vaccinated.
I know the topic of vaccination is rife with peril, so I’m going to just stick to the facts as I see them (or as I was taught in vet school). You will find piles and piles of opinions out there on whether or not to vaccinate your pet. I’m just going to give you my opinion and the protocol followed by my hospital for the puppy shots (since this is a puppy blog :-)
In a nutshell: I recommend shots at 8, 12, and 16 weeks. The reason puppies receive a "series" of vaccinations has to do with the immunity they get from their moms through the placenta and via the milk. This maternal immunity is called "passive" immunity and it protects the puppy from disease early in life. It wears off though, leaving the puppy susceptible to evil bugs like Parvo and Distemper.
The problem is that nobody really knows when maternal immunity wears off. The other problem is those disease fighting antibodies that the puppy gets from his mom also fight against the antigens (virus particles) in the vaccines given by the vet.
In order for a vaccine to work, you have to give it to the patient twice. The first time you give a vaccine, (assuming there is no maternal antibody to get rid of it), the puppy’s immune system goes into full emergency mode: "RED ALERT: BRAND NEW FOREIGN ANTIGEN PRESENT!" His white cells then get busy clearing all of that vaccine antigen. This takes about three to four weeks; the immune response peaks at two weeks.
The most important part of this process is the "booster vaccination," given at that three to four week point. When this vaccination is given, the body’s white cells go: "RED ALERT: WE’VE SEEN THIS FOREIGN ANTIGEN BEFORE! WE MUST REMEMBER THIS ONE!"
"Memory cells" are created after the second vaccination, giving the dog long term immunity. Subsequent boosters are basically just to "refresh" the memory of the memory cells.
If you revaccinate the puppy too soon, the immune system is still in peak antigen destruction mode. It just chews up the antigen without bothering to remember it. During this immunological feeding frenzy, vaccines given during this time don’t do anything to create any long term immunity.
Vaccinate too late and the immune system just forgets it was exposed the first time and treats it like an "initial" vaccination again. No memory cells. No long term immunity.
The reason we do shots at 8, 12, and 16 weeks is that we have to hedge our bets. Two out of the three shots have to be given after mom’s immunity wears off. Since we’re not exactly sure when that is, just that it’s somewhere between 8 and 12 weeks, we, as a profession, have chosen to give shots during both of these ages to "catch" that moment when the puppy’s mom-given immunity lags and his own immunity needs to get going.
With regard to which vaccines your puppy gets, that is a factor of where you live, who your vet is, and what your dog may be exposed to.
In my clinic, which is in north-central Texas, we generally give a DHP at the 8 week visit (Distemper, Hepatitis, Parvo); a DHLP (same thing, add Leptosporosis) and a Bordetella (not "bordello,"), AKA "Kennel Cough" at 12 weeks; and DHLP and Rabies at 16 weeks. We booster everything at the 1-year-old visit and individually tailor vaccines from there on out, depending on the dog, his lifestyle, etc.
I’ll cover the individual diseases in subsequent blogs.
Dr. Vivian Cardoso-Carroll