Why Puppy Vaccinations Sometimes Fail

Puppy vaccinations are an important step to building a healthy immune system for your new dog. Canine distemper, rabies, parvovirus and hepatitis vaccines are considered core vaccinations that all dogs should have to stay healthy. It is possible, however, for a puppy to contract a virus or bacteria after vaccination. There are several factors that may cause puppy vaccinations to fail.

Maternal Antibodies

Puppies have antibodies in their systems that have been passed from the mother through her milk. These antibodies offer adequate protection against disease but only for a short amount of time. For up to 14 weeks these puppies may have too many antibodies to allow a vaccine to work efficiently. This time period is known as the window of susceptibility. It is very difficult to calculate when a vaccine will be most effective in a puppy, so a series of doses are given to ensure proper protection.

Weaker Immune Systems in Young Puppies

Puppies are more susceptible to disease because their immune systems haven't had enough time to develop. If vaccines are given to puppies under six weeks old or with suppressed immune systems they are not going to be as effective as those given to older and healthier puppies.

Modified Live Virus Vaccines

Modified live virus (MLV) vaccines use a live but weakened strain of a virus to stimulate the production of antibodies to fight disease. This produces a stronger and longer-lasting immunity with fewer doses of vaccine. Sometimes the MLV vaccine can bring out the disease they are meant to protect against, especially in a puppy's developing immune system. On the other hand, a second type of vaccine known as a killed vaccine is less effective than MLV in penetrating the maternal antibodies in a puppy.

Poor Environmental Surroundings

Stressful physical surroundings like a crowded kennel, uncomfortable travel conditions or high temperatures and humidity levels can raises a puppy's body temperature. High temperatures and fevers will prevent effective vaccinations.

Failure of Vaccine

A vaccine may fail if it is mishandled or improperly stored or administered. Modified live virus vaccines are especially susceptible to failure if they are damaged, but this is a rare occurrence. Vaccines can be given in a variety of ways, including under the skin, through the nose or into the muscle. If a vaccine is not administered correctly or the wrong dosage amount is used your puppy will not be fully protected and possibly harmed.

Proper Timing Between Vaccinations

Vaccines given too close together in a short time period can interfere with the production of antibodies. If too much time passes by the immune system's memory and response may be affected. Veterinarians should wait 2 to 4 weeks between vaccinations and give one group of different vaccines at the same time rather than a few days apart.