Decreased Immunity in Older Dogs
Excerpt from Good Old Dog by Faculty of the Cummings School of Veterinary Medicine at Tufts University and Nicholas H. Dodman BVMS
One of the most common questions people ask veterinarians as their dog gets older is whether she still needs her vaccinations. In fact, a lot of people with dogs skip the vaccinations in later years, figuring that their pet has already been vaccinated against various illnesses a number of times and has gotten sick to that point, so why put the animal through more shots? It's a grave mistake. Older dogs need their shots even more than when they were young and middle-aged. The immune system, like other body systems, slows down in old age, making a dog more susceptible not only to diseases such as cancer but also to infections. She simply cannot mount a sufficient immune response to illnesses she might have been able to ward off in her younger days.
Consider the following scenario, which we have seen more than once. An older dog is not kept up to date with her vaccines, but her people continue to let her romp where as-yet-unvaccinated puppies roam, or they introduce a still-unvaccinated puppy into the household. The older dog ends up with parvo virus, which attacks the gastrointestinal tract and immune system and causes severe vomiting and diarrhea. It can also cause a secondary bacterial infection that spreads from the GI tract to the rest of the body, sometimes resulting in death.
It's precisely because of unanticipated exposure to vaccine-preventable viruses that an older dog's vaccination schedule must be maintained. Her age is not a signal to slack off but, rather, all the more reason to make sure she gets her regular shots. Modern medicine can really be useful to counteract a normal, age-related decline, and it should be fully taken advantage of.
For expert advice on veterinary care of your aging dog, purchase The Faculty of the Cummings School of Veterinary Medicine at Tufts University's Good Old Dog from Your Dog.