Why did the veterinarian order the vaccination of the puppy with core vaccine component, 3 times at 3-week intervals?
For over a decade canine vaccine has been categorized into core, non-core and non-recommended groups, with canine distemper, parvovirus and adenovirus considered as the core vaccine components. These categories have been further developed and currently form the basis of the World Small Animal Veterinary Association (WSAVA) Guidelines for the Vaccination of Dogs and Cats.
With regard to vaccinations of puppies, the WASVA guidelines recognize that maternally derived antibody (MDA) significantly interferes with the efficiency of most current core vaccines administered to pups and kittens in early life. The vaccine consists of attenuated living virus and therefore the antibodies identify it and lead to its destruction. As the level of MDA varies significantly amongst litters, the guidelines recommend the administration of multiple core vaccine doses to pups and kittens, with the final dose of these being delivered at 16 weeks or older and then followed by a booster at 6- or 12-months of age.
Vaccination of puppies and kittens as well as of neonates and infants is problematic with two main issues: the immature immune system and the presence of inhibitory maternal antibodies.
When a pup is born, its immune system is not fully developed making it susceptible to a variety of infectious agents. Fortunately, this is not the case for most of the neonatal, as they can receive passive protection from their mothers through maternal immunity.
Passive immunity occurs by the passage of antibodies to the fetus through the placenta (~3%), and more significantly, by the absorption of maternal antibodies of the newborn through the colostrum (~97%). Defined as the first 12-24 hours of milk flow following birth, colostrum is a highly concentrated mixture of large protein antibody molecules, vitamins, electrolytes, and nutrients. The pup can absorb the colostral antibodies into its blood system through the intestine only for its first days of life; the amount of absorption depending on the strength of each individual pup.
Unfortunately, the maternal antibodies will break down through natural aging of up to approximately 8-20 weeks. At this point, the MDA decaying (Blue line in the graph below) may not provide optimal protection and may even act as an inhibitor to the effectiveness of the vaccine (In between the two interrupted lines ~8-16 weeks). This situation is highly risky for the exposed and unprotected puppy. To avoid this situation the core vaccines are being given at 3-4 point intervals, as shown in the graph below.
Initial Vaccination (Dogs 16 Weeks of Age)
- Beginning as early as 6 weeks of age, the puppy is administered with sequential doses of a combination vaccine at an interval of 2 to 4 weeks until at least 16 weeks of age.
- Dogs that are 16 weeks of age when presented for initial vaccination should receive a second dose 2 to 4 weeks later.
- NOTE: Dogs residing in a HIGH-RISK environment may benefit from receiving a final dose at 18 to 20 weeks of age. HIGH RISK is a subjective assessment applicable to dogs residing at locations in which the incidence of CDV and/ or CPV is considered to be high; it may also include puppies known to have significant exposure to other dogs or contaminated environments.
- Measure antibody levels at least 2 wk following the last dose in the initial series to obtain confirmation of protective immunity against CDV, CPV, and CAV2.
- A single dose of a combination vaccine is administered within 1 year following the last dose in the Initial Vaccination series. Subsequent boosters should be administered at intervals of 3 years or longer.
- Measuring antibody levels (quantitative or qualitative) provides a reasonable assessment of protective immunity against CDV, CPV, and CAV2.