Today’s blog is a mini-immunology lesson. Before you jump ship, let me say that this topic is actually really exciting, because it’s a break from the common practice of giving vaccines to our pets every single year. Before we dive into this issue for pets, I’d like to share an example of vaccination on the human side of medicine. We’re all pretty much familiar with the MMR vaccine, protecting against measles, mumps, and rubella. Children age 12-15 months receive their first dose, and we give a second dose to our kindergarten-age kids. After this, we aren’t given this vaccine again. EVER. The Advisory Committee on Immunization Practices (ACIP) even states that for a person who has received two doses of MMR vaccine following the recommended schedule, who has a negative lab test for M – M – and/or R, no additional doses of vaccine are required. If you think about it, most vaccines given to people are not given every year, with influenza vaccine being the notable exception. The reason influenza vaccine is given yearly is due to the virus, which tends to mutate rapidly and vary in the strains of virus that circulate around the globe. Sometimes the influenza vaccine is quite similar from year to year. For instance, the 2013-2014 vaccine has two out of three components that are identical to the 2012-2013 vaccine. This means that for some who received the vaccine in 2012-13, they will have at least partial immunity to the strains of virus that are predicted to be most prevalent in 2013-14. I’m getting a little off track here while trying to illustrate that comparatively, we give far fewer vaccines to people, who live a lot longer than dogs and cats.
As noted in my previous blog posts about vaccine guidelines, the trend is toward longer vaccination intervals of 3 years or more for many of the core vaccines. Some vets, including Dr. Ronald Schultz and Dr. Jean Dodds, have taken a further step in recommending the use of “titer testing.” This test is simply analyzing the blood for the presence of antibodies, which the immune system produces after being exposed to an infectious agent or to a vaccine. The test tells us what memory the immune system maintains against diseases. By doing this test, we get a good idea of whether your dog or cat really needs to have a booster for diseases like distemper, parvo, and feline panleukopenia. This allows us to make an individualized plan for your pet, instead of the one-size-fits-all vaccination every year or even every three years.
What are the limitations of titer testing?
First, testing doesn’t give us answers for all dog and cat diseases. Studies have shown that titers correlate well with levels of immunity for canine distemper, canine parvovirus, canine adenovirus, feline panleukopenia, and Lyme disease. Titers don’t correlate as well for kennel cough, canine coronavirus, Chlamydophila, and FIP. Second, state laws for rabies require vaccination every three years, and states generally will not recognize titer testing in place of documented vaccination. Third, nothing in life is guaranteed. Just like there is no vaccine or medication that is 100%, having a positive titer doesn’t guarantee complete protection against a disease. It does tell us that the animal has immune memory and should be able to fight off an attack if it occurs. Finally, there is currently no universal agreement between labs about the optimal range of titer for a given disease. This means that if your vet used one lab to test for distemper titer this year and used a different lab next year, the report sent back from each lab will likely not look the same. However, each lab should include a range to help interpret the results.
Why should you consider titer testing?
You might be surprised to learn that the cost of titer testing is reasonable. In fact, if you consider what you would have spent on yearly or every three year vaccinations, you will probably come out even or slighly ahead. Relatively new to the market are in-clinic test kits that allow your vet to run the titer while you are there for your pet’s wellness exam. These kits are currently available for canine distemper, parvo-, and adenovirus. A kit for feline panleukopenia, herpes-, and calicivirus will be released soon.
Another benefit of reducing the number of vaccinations we give our pets is limiting both immediate side effects (such as low-grade fever, aching, loss of appetite, etc.) and much more serious long-term side effects. Feline injection-site tumors, called sarcomas, are one tragic outcome of repeated injections of vaccines and other medications in certain cats. In addition, cases of autoimmune and other degenerative diseases have been linked to vaccination.
The real goal of vaccination is preventive health care. As a veterinarian, I want to prevent deadly diseases in my patients without overwhelming them with unnecessary vaccines. Hopefully this makes sense to you as a pet parent. In the beginning of this post, I talked about the MMR vaccine and how humans get two doses for their whole lifetime. The virus that causes measles is very closely related to the virus that causes canine distemper. In fact, in the early history of vaccinating dogs for distemper, the human measles vaccine was used for a time.