Puppies are born with very few antibodies against disease. The mother will first produce colostrum. Colostrum is the first milk and is nature's way of providing newborn puppies with their first doses of antibodies to produce against disease. Puppies' bodies will not produce their own antibodies to disease until they are about six weeks old. Puppies must have at least one feeding of colostrum in their first 24 hours of life. By keeping the mother updated on vaccinations, she has a good chance of passing on her immunity to newborn puppies that helps to guard them against disease.

Access to colostrum is only good for the puppies in the first 24 hours of life. Access to the mother's colostrum in the first 24 hours of life is crucial.

The immunity to disease passed through the mother's colostrum called "maternal immunity" usually lasts for several weeks in the puppy's system. It gradually fades as the puppy's own immune system begins developing and becomes capable of producing its own antibodies at around 14 to 16 weeks of age. The exact time of maternal immunity's fading is very variable, but it generally occurs between 6 and 16 weeks. The goal of vaccination programs is to cover any gap in immunity by starting vaccines immediately after the maternal protection fades and when the puppy's body is capable of producing its own antibodies.

Vaccines are given to puppies several times to cover this gap. When the maternal immunoglobulins fade and leave the puppy without protection from disease, vaccines given at this time will prompt the puppy's maturing immune system to produce its own protective antibodies against disease. To be sure the series of vaccines given your puppy provides the immunity it needs, you can ask your vet for a Titer Test.

Do not vaccinate a pregnant shih tzu. You must do so before she is pregnant on a yearly basis.