Should I vaccinate an older dog?

Q: What is your opinion about vaccinating older dogs? As my two healthy senior dogs aged, their veterinarian increased the intervals between vaccinations. I worry that my dogs are now too old to safely vaccinate.

A: There is no evidence that vaccination increases the risk of any disorders in senior dogs. Vaccinations are spaced out as dogs age not because the vaccines are unsafe but because the duration of immunity is longer with repeated use. Depending on the vaccine, initial doses protect for three weeks to a year. Thereafter, some vaccines last longer than that.

The American Animal Hospital Association, or AAHA, makes recommendations about vaccinations and senior dog health care by relying on evidence-based medicine, i.e., rigorous, high quality research, not opinion.

The AAHA recommends core vaccinations for common, serious viral diseases, including distemper, adenovirus and parvo. If the dog received the initial vaccine series and a booster within a year, most studies show they retain protective antibodies to these viral diseases for at least three years. Rabies, another core vaccine, is boosted by the date shown on the rabies certificate. After initial vaccinations, that vaccine, too, is often repeated every three years.

Noncore vaccines protect dogs from diseases they may be exposed to based on geography and lifestyle. Examples are Bordetella, leptospirosis and Lyme vaccines, all of which protect against bacterial diseases. Research shows that duration of immunity isn't as long for bacterial diseases as viral diseases, so AAHA recommends vaccinating dogs at risk for these diseases every year.

AAHA doesn't recommend withholding vaccinations from senior dogs, because there is no evidence to support the practice. Indeed, elderly pets, like elderly people, often have poorer immune function than young and middle-aged adults, so vaccination boosters may be even more necessary in this age group.

I suggest you follow the recommendations of your veterinarian, who is in the best position to know your dogs' health and vaccine requirements.

Lee Pickett, V.M.D. practices companion animal medicine in North Carolina. Contact her at vet@askthevet.pet.