Vaccines prevent serious, life-threatening viral diseases and a proper vaccination program is important for any wellness plan for dogs. For puppies that means vaccinations every 4 weeks from 8 to 16 weeks of age against parvovirus and distemper virus. But, why give so many shots? Wouldn’t one shot with a booster be enough? The answer is no because the immunity mom gives to puppies inactivates vaccines.

What are vaccines?

Vaccines contain small amounts of virus from diseases they are designed to prevent. The virus is modified or in such small amounts that it cannot cause disease. But it is enough to stimulate antibodies against the virus that will protect the dog if exposed to that virus later in life. In my last blog (see below) I discussed how long that immunity to the virus will last. For puppies it is more complicated.

Maternal antibodies

Unlike humans, puppies do not receive any antibodies against disease while they are in the womb. Instead they only receive antibodies from the colostrum in mom’s milk their first 3 days of life. After 3 days the puppies’ intestines no longer allow mom’s antibodies to be absorbed into the blood stream.

Mom’s antibodies are very powerful but temporary. The antibodies disappear slowly until disappearing completely from the puppies’ bloodstream at 16 weeks of age. Until these antibodies reach low enough levels or disappear completely, they inactivate any vaccines given to the puppy. This graph will help.

The rate of disappearance varies from puppy to puppy and it is impossible to know which vaccine will “take” and which will be inactivated. Because we know that the antibodies will definitely be gone at 16 weeks of age, we know for sure our last vaccine will take. This last vaccine may booster any vaccines that may have taken before or be the only effective one. Either way the puppy is now protected from the virus.

By starting the vaccine series at 8 weeks, we protect puppies that may have not received adequate antibodies from mom’s colostrum. If we waited until 16 weeks to vaccinate these pups, they could become ill from the virus prior to that 16 week vaccination.

The monthly vaccination program for puppies has been developed to protect as many puppies from a litter as possible no matter what their maternal antibody status