Saturday, April 17, 2010

Vaccines....Too much of a good thing?

Vaccines! To give, or not to give? Yearly, Every three years? My vet sends me a reminder card every year, so I need to "booster" yearly, right?

Regarding the core canine vaccines for parvovirus, distemper and adenovirus; ONE effective vaccine dose should confer a lifetime immunity. The stumbling block remains the attainment of an "EFFECTIVE" vaccine dose.  A vaccine may NOT be effective if the dog is ill, stressed, or already incubating the disease. A puppy may still have maternal antibodies lingering in his circulation that can block the effectiveness of a vaccine. The reason that vaccines are given as a series to puppies is because one can't know at precisely what age antibodies received passively from the mother have disappeared. By age 4-6 months the maternal antibody interference should have worn off.

Just like with people, once you have had measles, mumps, german measles, chicken pox, smallpox....either the disease of the are immune. No need to "booster".

The core vaccines for dogs protect against diseases that happen to be caused by viruses. Bacterial diseases,  however, are another story. There is no such thing as lifetime immunity to bacteria. So if your dog is at risk for lyme disease, leptospirosis or bordetella, he may need repeated "booster" vaccinations...but only for those particular bacterial diseases. And ONLY if he is at risk. For instance, if your dog frequents wooded areas, he may be at risk of lyme disease or leptospirosis. If your dog is around many other dogs, such as a kennel or a dog show situation, he may benefit from the bordetella vaccine for kennel cough.

Vets figure that it doesn't hurt the dog to get a yearly vaccine and it gets you into the office....that's why they send out those reminder cards. Adverse reactions to vaccines can sometimes occur, so it makes little sense to vaccinate unless it is truly necessary.

The AAHA recommends no more often than three years for the core vaccines....and that is only because there are no long-term official studies on duration of immunity. This is where the rabies challenge fund will help all of us, because rabies is a vaccine with a high rate of adverse reactions. Some areas require rabies re-vaccination as often as every year.

Print this out and take it to your vet if he/she is pushing for yearly vaccination. These are the most recent official veterinary guidelines.
A few thoughts on recent immune system theories....

An interesting recent genetic discovery is that the "K" locus not only codes for dominant black coat color, it is also gene that is a "beta defensin"....a protein that plays an important role in the immune system. Is strong black pigment an important indicator of a healthy immune system? Small white dogs are noted to be at higher risk of adverse vaccine reactions, so perhaps lack of eumelanin (black) can be one indicator of a compromised immune response. Black dogs may well have a definite health advantage that can be discerned by their appearance!

When two dogs who are very genetically similar are mated, the offspring can receive the same set of genes from each parent in the Major Histocompatibility Complex or "MHC". The more diverse the genes in the MHC, the stronger the immune system. Dogs that are known to have many matching chromosomes, such as purebreds with recessive traits doubled up and expressed, are often noted to have impaired immunity. This has long been evident in such breeds as Weimeraner (double recessive dilute) and Rottweilers and Dobermans (recessive tan point pattern). These dogs are likely not only homozygous for their coat color but for their immune system genes as well. This condition of being homozygous in the MHC in essense cuts the effectiveness of the immune system in half!

Hopefully more research in the area of immune system function will encourage breeders to produce dogs with a bit more diversity and an improved immune response. This is my fervent hope for the future of dogs!


  1. Could you give a reference for more information regarding "K" locus coding for "beta defensin"?

    Also, a reference for Major Histocompatibility Complex, I want to learn more about MHC. Thanks for a concise statement on MHC.

    Very interesting!

  2. "The K locus is the gene beta-defensin 103. (Testing for homozyougs black will be available shortly at HealthGene.)"

    "The gene is a beta-defensin. This family of genes has been known to play an important role in immunity in humans, mice and other animals previously. This is the first time that a defensin gene has been shown to affect pigmentation though."

    Here's a page that is also useful:

    Regarding the MHC:
    The portion of the genome that codes the genes that help us recognize “self” is called the MHC-the Major Histocompatibility Complex. These genes are located very close to each other and it is rare for recombination to occur. This in effect means that the genes from each parent are inherited intact. (Remember, you inherit genes in pairs, one from each parent). If the parents are closely related, the possibility exists that they share the same genes at that site…they are “homozygous by descent”. If so, there is a high likelihood that their offspring will inherit identical genes in the MHC. It appears that susceptibility to an autoimmune disease is determined by the lack of variability in the MHC genes. Linebreeding and inbreeding may result in this lack of variability. Close breedings increase susceptibility in the offspring to develop an autoimmune disease when an environmental trigger is present.

    From Dr Susan Thorpe-Vargas:
    Loss of immune function. Inbreeding, referred to as line breeding by many dog and cat breeders, leads to loss of immune function. In order to function, the immune system has to be able to recognize “self” from “non-self”. The portion of the genome that codes for the genes that help us recognize “self” is called the MHC--the Major Histocompatability Complex. These genes are located very close to each other and therefore it is very rare for recombination to occur. This in effect means that the genes from each parent are inherited intact as haplotypes.

    If the parents are closely related, then the possibility exists that they share the same genes at that site, i.e., they are homozygous by decent. In a highly inbred population, what is the likelihood that the parents share the same haplotypes? What happens to the puppies or kittens that inherit a duplicate copy of that same haplotypes? This would essentially cut the functionality of the immune response in half - not a good thing."

    Inbreeding Effects on Immune System