Titer Testing: a Simple Blood Test

Enlightened veterinarians and pet parents have become increasingly wary of the health risks, and lack of benefits, associated with repeatedly vaccinating dogs after their initial “puppy shots.” Is titer testing the solution to the over-vaccination problem? Here’s a crash course to help you muddle through the mire of misinformation surrounding this simple blood test, and to help you decide whether or not to test your dog’s antibody titers.

What is titer testing? A titer test (pronounced TIGHT er) is a laboratory test measuring the existence and level of antibodies to disease in blood. Antibodies are produced when an antigen (like a virus or bacteria) provokes a response from the immune system. This response can come from natural exposure or from vaccination. (Note: titering is also called serum vaccine antibody titering and serologic vaccine titering.)

How is the test performed? Your test result will have an explanation of what your pet’s test result means. But if you want to know more, here’s the test in a nutshell: First, one mL of blood is drawn. The sample is then diluted. Titer levels, expressed as ratios, indicate how many times blood can be diluted before no antibodies are detected. If blood can be diluted a 1000 times and still show antibodies, the ratio would be 1:1000. This is a “strong” titer. A titer of 1:2 would be weak.

Should I test for all diseases? The most recommended test examines antibodies for both parvovirus and distemper, the two most important viruses. Rabies titers are also often tested. Usually, for most dogs, tests for other diseases are generally not considered useful or necessary.

Why test? The parvovirus/distemper test can help you or others (vets, groomers, kennel owners, etc.) determine if your dog requires additional vaccination, and may save your dog unnecessary shots. It is especially useful when making a decision about vaccinating an animal with unknown vaccination history, or for determining if puppies have received immunity from vaccination (more below).

Most experts believe strong titers are a more reliable indication of immunity than vaccination: tests show the actual immune response, not just the attempt to cause an immune response by vaccination. Do not expect, however, that everyone will accept test results in place of proof of vaccination.The subject of immunity is complicated, and we are programmed to think of vaccination as “the gold standard” — the more, the better. Experts who challenge the status quo are often maligned. Humans don’t like change.

How often should I test titers for parvo and distemper? You’re going to have to decide for yourself. Some vets recommend testing yearly, but this can be expensive. Others test every three years. Still others test five to seven years after vaccination. Why? Challenge tests show that successful vaccination against parvovirus gives most animals at least seven years of immunity. Distemper provides immunity for at least five to seven years.*

Dr. Ron Schultz, one of the most renowned pet vaccination experts in the country, believes that once a test yields strong titers, you need not test again.  In Dr. Jean Dodd’s article on vaccine reactions, she quotes Dr. Schultz on the value of testing titers: “an animal with a positive test has sterilizing immunity and should be protected from infection.  If that animal were vaccinated it would not respond with a significant increase in antibody titer, but may develop a hypersensitivity to vaccine components (e.g. fetal bovine serum).”

Does a weak titer mean that the dog needs a “booster” shot? Maybe not for dogs that have previously shown strong titers. Many experts, including Dr. Schultz, say the dog’s immune system will have produced “memory cells” that will produce antibodies when they’re needed. Think of memory cells as reserve forces. When known foreigners invade, they remember how to attack them.  Dr. Shultz has said, “show that an animal with a positive test has sterilizing immunity and should be protected from infection.  If that animal were vaccinated it would not respond with a significant increase in antibody titer, but may develop a hypersensitivity to vaccine components (e.g. fetal bovine serum).Read more about memory cells here. Read pages 5-6 of Antibody Titers vs Annual Vaccination by Richard Ford, DVM for more information.

Should I test my puppy? Yes! If so, when? Ideally, puppies should have had their last vaccination after 16 weeks of age then should be tested to see if further vaccination is necessary. There’s an excellent discussion about testing puppies in the 2006 American Animal Hospital Association (AAHA) Canine Vaccine Task Force Report (page 13) entitled What Are The Possible Applications of Serologic Testing? It reads, “Such titer testing is the only way to ensure that a puppy has developed an immune response after vaccinating.”

What do titer tests cost? Testing costs vary widely from practice to practice, so shop around. Some vets do in-house testing. Others use outside labs. Some mark up tests and services a little; others, a lot. You should be able to have parvo/distemper tests done most places for less than $100. Rabies tests, on the other hand, can cost considerably more, in large part because they are sent overnight to a lab. (Ask your vet to have a Titer Testing Day so that they can send multiple tests in one package and save considerably on shipping costs.) Consider contacting Hemopet, Dr. Jean Dodd’s nonprofit organization, for their pricing and her excellent reading of results. When comparative shopping, make sure pricing includes blood draw and shipping.

Wait! Before jumping to the conclusion that vaccinating is much cheaper than testing, remember that testing can be a one-time (or at least rare) expense and is no riskier than any simple blood draw. Vaccinating, on the other hand, can potentially cause a lifetime of illness.

Should I test for rabies antibodies? The rabies titer test will give you an indication of your dog’s immunity if he or she is at particular risk for contracting rabies. It may also be required prior to international travel. Test results will NOT be accepted by Animal Control and most others as a substitute for vaccination of healthy dogs as required by law.

If your dog has documented health problems or documented adverse reactions to shots, your vet may be able to get your dog an exemption to rabies vaccination. (Learn more at www.Truth4Dogs.org.) A rabies titer test is not usually necessary when requesting an exemption but may be useful when re-applying for a denied exemption. It may also give you and others piece of mind if you’re contemplating an exemption.

(Note: a French challenge study has shown rabies vaccination gives immunity for at least five years. In the U.S, the Rabies Challenge Fund is doing concurrent tests for five years and seven years to extend the period between shots. This important nonprofit study is funded solely by donations from dog lovers like you.)

Can I test titers immediately after vaccinating? To get an accurate test, you must wait at least 14 days after vaccination before testing.

What if your vet, groomer, spouse, best friend, kennel owner or day care proprietor says titer testing is “voodoo science,” that your dog needs continued vaccination even if testing indicates otherwise? Know that vets out of school longer than 10 years received little or no immunology or vaccinology training in school; they shouldn’t be considered experts unless they’ve devoted hundreds of hours to research and training. Others who want to influence you may have no training at all and may be acting out of fear. Do your own research and advocate for your dog.

I hope I’ve given you enough information to make reasoned decisions. The subject is hardly black and white; it is riddled with shades of gray. I’d like to thank veterinary crusaders against over-vaccination Drs. Margo Roman and Tamara Hebbler for their help with this article, and Drs. Jean Dodds and Patricia Jordan for answering my many questions about vaccination over the years.

Where can you learn more? Visit my web page Vaccinating Dogs, and also the articles and videos archived on this blog by clicking the “Vaccination” link. For in depth  information in an easy to read format, see my “Rethinking Vaccination” chapter in my award-winning book, Scared Poopless: The Straight Scoop on Dog Care.

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* Challenge studies prove immunity by exposing an animal to a disease. These studies show distemper immunity given by the Rockborn Strain gives 7 years immunity; the Onderstepoort Strain, 5 years. Ask your vet which strain was used to vaccinate your dogs. Read more by clicking here.

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