A puppy’s first source of immunity comes from colostrum, derived from its mother’s milk in the first 48 hours after birth. After that time, insulin production will interfere with a puppy’s ability to absorb maternal antibodies this way. However, puppies can still derive immune protection from their dam’s milk as long as they continue to nurse or her milk supply fails. Immunoglobulin G and A in the milk provides protection against infections of the mouth, digestive system, and intestinal tract- the most common routes of infection puppies will encounter. This is a major reason why puppies should not be weaned early.

Maternal immunity begins to wane by 6-8 weeks and no longer provides effective protection when puppies are between 12 and 16 weeks old. By this age, a puppy’s immune system becomes functional to compensate. An immature puppy’s immune function is dependant on the development of major organs and hormone levels and vaccinations will not be fully effective until its immune system is fully functional

Vaccinations administered to puppies younger than eight weeks are likely to be ineffective due to a combination of the puppy’s immature immune function and the potential interference of maternal antibodies.

All puppies should be vaccinated against distemper, parvo, hepatitis and rabies. These are known as the core vaccines. Puppy vaccinations are generally given in three combined doses known as the DHLPP: distemper, hepatitis, lepto, parvo and parainfluenza.

The first shot is usually administered at eight weeks, followed up by two booster shots given at three to four week intervals. Rabies vaccine should always be administered separately, at least one month after the DHLPP series.

Vaccinations should never be administered to a puppy whose immune function is compromised by stress or illness.

Today, most vets and breeders prefer to revaccinate every three years rather than annually. Vaccines against viral diseases like distemper and parvo provide several years immunity. This duration can be much shorter for bacterial diseases like kennel cough (bordatella) and lepto. Dogs at risk for these diseases may benefit from annual or semi-annual vaccinations. Intransal vaccines for kennel cough have been shown to provide better protection with a lower risk of side effects.

Many breeders do not to give lepto vaccinations, fearing possible vaccine reactions long associated with this component. Newer versions of the lepto vaccine have been designed to minimize possible reactions. However, most combination vaccines protect against only two strains of lepto. A recent resurgence of the disease in many parts of the US and Canada has been attributed to lesser known strains normally not included in combination DHLPP vaccines. Fort Dodge is now manufacturing a four way lepto vaccine to protect against all four prevalent strains.