I’m afraid that sometimes I get distracted by the more esoteric aspects of veterinary medicine — the latest and greatest treatment for some rare disease that most of you (hopefully) will never encounter. I want to take some time to focus on something that all pet owners have to deal with … vaccines. Specifically, trying to help you understand how veterinarians determine which preventative vaccinations a particular dog should and should not receive.

To answer this question, it is helpful to divide vaccines into two categories: essential and situational. I’m going to take care of the low hanging fruit today — essential vaccines. In future editions of the series, I’ll talk in detail about what influences recommendations for or against each of the commonly used situational vaccines (e.g., parainfluenza virus, Bordetella bronchiseptica, canine influenza virus, Lyme disease, and Leptospira interrogans).

Essential vaccines are those that are required by law and/or prevent especially contagious, widespread, or severe diseases. The essential vaccines for dogs are rabies, canine distemper virus, canine parvovirus type 2, and canine adenovirus type 2. Every dog should receive these on a schedule known to provide them with continuous protection or (except in the case of rabies) be monitored via serology (titers) to determine when a booster is needed. Exceptions can be made when a serious health concern (e.g., a previously documented anaphylactic reaction or a current diagnosis of serious disease) makes the risk of vaccination higher than its benefits.

Rabies vaccines for dogs are required by law. State, local, and municipal statutes must be followed. Most do not recognize titers as being a substitute for vaccination and will provide exemptions under very limited circumstances (e.g., a documented life-threatening reaction to a previous rabies vaccination in combination with a lifestyle that strictly limits exposure to wildlife and poses a negligible risk to public health). Many states only recognize rabies vaccines that are given by a veterinarian or under veterinary supervision. According to rabies vaccine labels, dogs should be vaccinated once they reach 12 weeks of age, and this vaccine is good for one year. The booster that is given in one year’s time and all subsequent boosters are good for three years. Local laws may require a different vaccination schedule, however.

Canine distemper virus, canine adenovirus type 2, and canine parvovirus type 2 vaccinations can all be given according to the same schedule. In fact, they are combined in a single “shot” that goes by the abbreviation DAP. Puppies should begin receiving DAP vaccines between six and eight weeks of age and then receive a booster every 3-4 weeks until they are 16 weeks of age.

The last dose must be given between 14 and 16 weeks of age to ensure the immunity derived from mother’s milk that can inactivate vaccines has waned. Depending on when puppies start the series, they will receive a total of either 3 or 4 vaccines. An additional DAP booster should be given at the dog’s one year check-up. Adult animals with an unknown vaccination history can receive a single, initial DAP vaccine.

Research has shown that the immunity produced by DAP vaccinations in an adult dogs lasts at least three years (probably longer). Therefore, revaccination every three years or running intermittent titers to check antibody levels are both reasonable options. When a dog that has been vaccinated for DAP multiple times reaches an advanced age, which I define as approximately ¾ of life expectancy, both vaccinations and titers can usually be stopped.

Dr. Jennifer Coates

Image: Robert Kneschke / via Shutterstock