We have long advised puppy owners to have their vet run a “vaccine titer test” a few weeks after the series of “puppy shots” were completed. In our view, adopted from that of the canine vaccination experts we most respect (Ron Schultz, PhD, who has been involved in the development and testing of most of the vaccines used on dogs in this country; and W. Jean Dodds, DVM, a veterinarian who has extensively studied and written about canine vaccines), only a positive vaccine titer test can tell you whether the puppy’s immune system responded to the vaccines in the manner that was intended.
A brief refresher: Puppies are born with antibodies from their mothers still circulating in their bodies. (Some of these they gained from the blood they shared with their mothers via the umbilical cord, and some from the colostrum that they drank in the first couple of days after they were born). These antibodies “fade” (disappear) at a variable point – from a few weeks to as much as six months after the birth of the puppy.
A vaccination is a weakened, modified, or killed strain of disease antigen – the substance that could otherwise cause disease. We administer disease antigens to a dog or puppy in order to “teach” their immune systems to recognize them as invaders, so they produce antibodies that are specifically designed to recognize and neutralize those antigens. If the animals are later exposed to one of these disease antigens in a live, virulent state, the antibodies will recognize the antigens and annihilate them before they can infect and sicken the dog.
When his mother’s antibodies are circulating in a puppy’s bloodstream, and we vaccinate him (with disease antigens), the mother’s antibodies recognize those antigens and neutralize them. When this occurs, the puppy does not develop his own antibodies (protection) from the vaccines he was given. This mechanism is known as “maternal interference” – the mother’s antibodies have interfered with the vaccine. That’s why we vaccinate the puppy again and again: because until this maternal interference fades, the puppy’s own body can’t begin to recognize the disease antigens in the vaccines and develop his own antibodies to those diseases. Pups are vaccinated two to three weeks apart, in an effort to minimize any potential gap in coverage (between the fading of the maternal immunity, and a vaccination and resulting development of the pup’s own immunity).
On four separate occasions, my son’s new pup, Cole, was vaccinated at the shelter from which he was adopted. His age was estimated to be six months – the time when a puppy’s maternal interference is almost always gone – when I took Cole in for a vaccine titer test, to make sure he was what’s called fully “immunized,” not just “fully vaccinated.” In other words, to make sure he had developed his own antibodies to the diseases for which he was vaccinated.
Guess what? He hadn’t. The result of Cole’s titer test for distemper was negative. We assumed (like almost everyone does) that after all those puppy shots, he was protected, but if he had happened to come into contact with a dog or pup who had been infected with distemper, or had been someplace an infected dog had recently been, Cole could have contracted this often fatal disease.
Thanks to our knowledge, gleaned from the experts who inform WDJ, we found out that he was unprotected, so we vaccinated Cole again. We’ll run another titer test in about three weeks, and keep him away from dog parks and sidewalks until we have the results. And I will discuss vaccinations, titer tests, and Cole’s situation at greater length in the April issue.