Vaccinations...why we recommend what we do.

Vaccinations and vaccine protocols are controversial areas of veterinary medicine that we share in common with our human physician counterparts.  Most people understand that vaccinations help to reduce the incidence of disease but may not fully understand how.  Vaccines present the disease (antigen) to the immune system in a form that is unlikely to cause illness, and therefore allow the body to produce antibodies to the disease.  With antibodies in circulation, the body is able to fight the disease if the antigens are encountered again. The antibodies will bind with the antigen and through various mechanisms the antigen will be neutralized.   

Vaccinations are classified in three different categories: killed (or sometimes euphemistically called inactivated), modified-live, or recombinant.  Killed vaccines are self explanatory, the organisms are dead but still may be recognized enough by the immune system to cause an immune response.  In order for the immune system to have the best chance at developing an immune response, killed vaccines typically have adjuvants added.  Adjuvants are ingredients that cause inflammation.  They can be cell walls or other products.  Their actual composition is typically a trade secret and is different between the various vaccine manufacturers.  Killed vaccines are unlikely to cause the disease, but they may not give the best immune response.  With diseases such as rabies, killed vaccines are favored, often by law, so that we do not inadvertently cause disease.    

Modified-live vaccines contain organisms that would generally cause disease, but they have been attenuated.  Attenuation is a process whereby the organisms are reproduced in a laboratory for numerous generations until a version is identified that does not cause disease.  The benefit of a modified-live vaccine, such as a bordetella intranasal vaccine for dogs, is that once it is administered, the organisms will reproduce and will stimulate an immune response, but not cause disease.  Therefore, modified-live vaccines do not have a requirement for adjuvants to be present to cause additional inflammation.  This is of benefit because adjuvants have been linked to possible side-effects in some patients.  Some people worry that modified-live vaccines will cause the disease we are trying to prevent.  In rare cases, a patient may develop mild clinical symptoms associated with a modified-live vaccine, but the symptoms are usually very mild and quickly resolve. The long-term protective effects of these vaccines definitely warrant taking this slight risk in most cases. 

The third category of vaccines is recombinant.  Such a vaccine is really a cross between a modified-live and killed vaccine.  They push the boundary of how we define the word "live".  Are viruses actually alive?  Some would argue that they are not because they cannot reproduce on their own, but that is a philosophical discussion for another time.  With recombinant vaccines, a snippet of DNA or RNA (the genetic material that forms the basis for life) is removed from the disease-causing organisms and is spliced into the genetic material of a "live" but harmless virus.  That way it can reproduce once injected, not cause disease, but also stimulate a good immune response.  An example of this would be the canarypox rabies vaccine for cats.  The canarypox is the harmless virus that has had a bit of rabies spliced into it. 

When we recommend a vaccine for one of our patients at Poulsbo Animal Clinic, we have already taken the characteristics of various vaccines into account prior to making our selection and suggesting it to you.  We strive to choose vaccines with safety and efficacy in mind.  We also take your pet's health status, lifestyle, and other factors into account before we make a recommendation.  Vaccination is not a one-size-fits-all proposition.  There are core vaccines that all animals should have, such as Rabies, the DAPP combination for dogs (Distemper, Adenovirus, Parainfluenza, Parvovirus) and the FVRCP combination for cats (Feline Viral Rhinotracheitis, Calicivirus, Panleukopenia).  There are also non-core vaccines such as Bordetella, Canine Influenza, or Feline Leukemia that are recommended based on risk factors. 

Vaccinations are controversial but of critical importance in our efforts to reduce disease in our veterinary patients.  There are a lot of factors that we consider every time we recommend a vaccine.  We truly have your pet's best interest in mind when we vaccinate them.  There are numerous vaccines that are on the market that we could sell but that we do not even carry in our inventory because they are not effective, not necessary, or not safe enough to justify their use.   This is a detailed subject that cannot be fully explored in a short article.  I would enjoy any questions you may have or suggestions for any clarifications I can try to make.

Best regards,