Puppy Vaccinations: How they work and why your pup needs so many.

Jelly and her puppies. Thanks to Judy at Victory Retrievers for use of this photo.

As regular readers of this blog know, I am a big fan of The Whole Dog Journal. It has long been my go-to reference for all things canine, but I am, regrettably, not always on top of my reading. Today I found an article in my “must read” list called Puppy Vaccines: Why your puppy needs so many shots, by Nancy Kerns, and my biggest regret is that I didn’t read and blog on it sooner!

One of the things I liked the most about the article was the clear explanation of why your puppy needs so many repetitions of the core vaccines. Like many people, I thought it was because multiple shots were necessary to achieve full immunity. Not so!

As she puts it: 

Few new dog owners understand why puppies need multiple “shots.” Most veterinarians recommend that puppies are vaccinated for distemper, parvovirus, and adenovirus (hepatitis) a number of times, starting when they are about four to six weeks old, and again every three or four weeks, with their last “puppy vaccination” given after they are about 16 to 20 weeks old. The most common guesses as to why puppies need all those vaccinations?

A) Because it takes at least four vaccinations for full immunity.
B) Each shot “boosts” the immunity from the first shot.

The actual answer would be C) Neither of these. Repeated puppy vaccines do not increase or “boost” the immunity in any way. Vaccines are repeated in order to make sure the puppy receives a vaccination as soon as his immune system is able to respond as we want it to…by developing antibodies to the disease antigens in the vaccines. (Emphasis mine.)

Vaccination protocols vary a lot*, but the common thread is that in order to insure that a puppy develops immunity to these devastating diseases, they need to be vaccinated frequently, because there is no way to tell when the immunity they got from their mother is going to wear off (if they got it at all).

All puppies who are nursed adequately by their mother in the first two or three days after birth receive some of her protective antibodies from drinking her “colostrum” – the yellowish substance that the mother produces before she starts actual milk production…The mother’s antibodies protect the puppies for a highly variable amount of time – anywhere from about three weeks to about 12 weeks. These antibodies gradually “fade” from the puppies’ systems as the puppies’ own immune systems develop.

As long as the mother’s antibodies are active in the puppy, he will not develop his own antibodies. If the puppy loses his mother’s antibodies at 3 weeks of age and gets vaccinated at 4 weeks of age, he will develop his own immunity, and not require any additional vaccinations. But, if he doesn’t lose his mother’s antibodies until 14 weeks of age, his body will not have developed its own immunity, despite having had several shots. Thus, he needs the 16 week booster shot. 

Perhaps more importantly: “There is no practical way to know whether the mother’s antibodies are still circulating in a puppy’s body or when they have faded. And each mother and each puppy is an individual; she will pass along a variable amount of antibodies, and these will fade at different times in each puppy. So we vaccinate several times, until we are past the point in time when any maternal antibodies can interfere with proper immunization.” (Emphasis mine.)

It is this variability in knowing when a puppy has developed full immunity that has veterinarians cautioning owners to limit their dogs’ exposure to other dogs, and places where a puppy could become ill until the dog is 16-18 weeks of age. I understand this precaution, and I certainly do not want any puppy to become sick, but there are other important reasons why your dog does need to interact with the world during this critical socialization period.

The key is to be judicious and careful about where and how your dog is exposed to the world. Do take him to a good puppy class; have friends and family over to visit, and “bring him to the homes of relatives and friends whose dogs are demonstrably healthy, vaccinated, and friendly. Do not take the puppy for walks in places that are highly trafficked by unknown dogs, such as sidewalks, parks (especially dog parks), pet supply stores, and so on.” With some forethought and planning, you can have a healthy immunized dog who is also a social superstar!**


*This variability is due to numerous factors. Puppies in shelters whose mothers vaccination record is unknown may need more frequent vaccinations to achieve immunity, whereas puppies from a reputable breeder may have better maternal interference and need fewer repetition of shots.

**On our podcast, Your Family Dog, Colleen Pelar and I have done several episodes on puppies which can be found here:

With Dr. Leanne Lily of OSU:

With Dr. Christopher Pachel on puppy socialization:

Puppy Socialization with Dr. Christopher Pachel, Episode 1: Trauma and Your Puppy

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