Are Vaccine Titers Useless?


Dr. Barchas,

I’m one of those pet parents obsessed with doing right by our cat. We have cat trees, a variety of scratching posts, make sure he gets playtime everyday and we feed our cat a raw food diet (Nature’s Variety).

I am 100% a believer in vaccination. However, I am concerned about over-vaccination as most “holistic” vets say that most vaccinations last 5+ years and that some animals get tumors from repeated vaccinations. My solution to this is to pay for vaccination titers to be done every year and if my cat is no longer immune to various diseases we get a vaccine.

This system was fine with our old vet in NYC. But now that we’re in the ‘burbs our new vet objects to this system and says titers are useless. What do you think we should do?

Staten Island/New York, NY

Like you, I am a believer in vaccines. Totally unvaccinated animals die at high rates from preventable diseases.

Like you, I also worry about over-vaccination in pets. You are correct that some vaccines (rabies and feline leukemia, to be specific) have been linked to cancers in cats. You also are correct that most vaccines probably work for at least five years in adult animals.

Here’s the rub. Every individual responds differently to each vaccine. A single feline panleukopenia vaccine will lead to lifetime immunity in most cats and kittens. But there are exceptions.

Although most vaccines probably work for at least five years (or more likely longer) in most animals, there will be variations between individuals, and allowing half a decade to pass between vaccines may (may) result in animals being vulnerable to infectious disease.

There are two ways around this problem. One is simply to booster vaccines at regular intervals. The overwhelming majority of pet owners take this route. I recommend core booster vaccines at no greater frequency than every three years (unless rabies is required annually in your municipality).

A much better way around the problem would be to measure each animal’s individual immunity and then vaccinate only when necessary. That’s the idea behind titers. Titers measure antibody levels in the blood. Antibodies levels give an approximation of immunity.

However, titers only measure the function of one portion of the immune system, called humoral immunity. They do nothing to measure the other main system, called cell-mediated immunity. Without cell-mediated immunity the immune system cannot function.

It is my opinion that titers are very useful but not perfect. They provide valuable information. But they don’t provide all of the information one needs to completely assess the immune system.

So we are left with a choice of using titers as an approximation of immune system function and possibly being wrong, or simply boostering vaccines and probably over-vaccinating.

Given that choice, I think titers are the better bet. I recommend that you should stick to your system.

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