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 categorised 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 guide lines recognizes 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 neonates and infants is problematic with two main issues: the immature immune system of neonates 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 new born 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 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.
- 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 year or longer.
- Measuring antibody levels (quantitative or qualitative) provides a reasonable assessment of protective immunity against CDV, CPV, and CAV2.
Most puppies are vaccinated several times at 6, 9 and 12 weeks, as it is known that maternally derived antibodies can cause a vaccination to fail. However, is that sufficient? How do you know whether your dog is protected?
Pups are given, right after birth, via the first mother's milk, (colostrum) antibodies, that will protect against infectious and fatal diseases. These so-called maternally derived antibodies are temporary and disappear gradually, but can be present in the blood of the pups for up to 20 weeks or longer. If, however, the mother dog has no, or too few antibodies, the pups will not get them through the colostrum and are unprotected! It is important to protect puppies at the right time by means of a vaccination that stimulates the body to produce antibodies. This ensures permanent immunity.
The goal of a vaccination is to make dogs immune to certain diseases. However, it is a misconception to think that all animals, that have been vaccinated, are actually protected. A vaccination does not automatically lead to protection in young animals, that are still protected by maternally derived antibodies. In the Netherlands and Belgium, pups are usually vaccinated at 6, 9 and 12 weeks. The last vaccine of the puppy vaccination schedule will be administered around the age of 1 year, and then every 3 years they are vaccinated against infectious hepatitis, parvo and distemper.
Most pups are vaccinated several times, because it is known that maternally derived antibodies can block a vaccination. By administering a vaccine regularly every 3 weeks, there is a chance that one will catch. The problem lies in the fact that most puppies get their last vaccination at 12 weeks. As maternal immunity can last up to 20 weeks, and sometimes even longer, there is a big chance that they will walk around unprotected for up to 1 year, the age at which they receive the last vaccination of the vaccination schedule. People mistakenly think that their dog is optimally protected by this vaccination, but there is still at risk of contracting and spreading diseases. The dogs will then go unprotected to dog schools, boarding kennels, shows, competitions, animal events, dog parks and so on.
Optimal vaccination schedules
It would be much better, and more responsible, to adjust the current vaccination schedule according to the vaccination guidelines of the WSAVA. The WSAVA is a scientific committee, which sets out guidelines worldwide regarding the vaccinations of dogs and cats. In these guidelines, it is stated, that among other things, it is not wise to administer the last vaccination before the age of 16 weeks. There are two possibilities:
- A titer determination at 20 weeks. If the result is positive, the dog does not need to receive extra vaccination and the animal can be tested again after a certain period, depending on the result.
- To advance the vaccination normally given at 1 year, to 26 weeks. This is to prevent the animal from walking around unprotected until the age of 1 year.
Most puppy buyers receive a puppy that has been vaccinated once in the litter. Such a puppy can be tested 3 weeks after the vaccination. At that moment, it is not always clear whether the antibodies, that are being measured, come from the mother or from the vaccine. Therefore, a few weeks later, a new titer test is required. If the titers have dropped, then it is certain that these are maternally derived antibodies. Depending on the level of the antibodies (antibody titers) at that time, the pup can then be vaccinated or be retested at intervals of a few weeks, when they are sufficiently low to vaccinate successfully. If the titers remained the same, then this is a sign that the vaccination has been successful. Unfortunately, most puppies in the Netherlands and Belgium are usually only vaccinated against distemper and parvo, so they still have to be vaccinated with a cocktail that also contains infectious hepatitis.
The best and most effective method is to titer test a pup, who has not yet been vaccinated, just before it leaves the litter. If the test shows that sufficient maternally derived antibodies are still present, vaccination is pointless, as the antibodies will neutralize the vaccine. You would then retest the pup, who is probably already with the new owner, after about 3 weeks. If the level of antibodies has declined below the protective level and the level at which a vaccination can immunize, a cocktail containing modified live viruses of infectious hepatitis, parvo and distemper has to be administered.
Subsequently, a titer test is performed about 3 to 4 weeks after this vaccination, to see if the puppy actually has enough antibodies in the blood, and is protected against the diseases mentioned. If this is the case, it means that the dog is immunized and fully protected against the mentioned diseases, by just one vaccination. As the animal is still very young and the immune system has not yet fully developed, a year later it makes sense to test it again to see if the protection is still good. If this is the case, titer testing can be performed triennially, according to the WSAVA guidelines.
The most commonly used titer test is VacciCheck. This is a reliable in-house test which can be performed by the veterinarian himself. Only a very small drop of blood is needed and the result is known within half an hour. The veterinarian must indicate in the vaccination pet passport how long the dog will be protected and thus, a validity period is linked to the declaration, according to Dibevo, KNMvD, NVWA and KMSH.