Veterinarians and dog owners question the need for certain booster vaccinations.

It was obvious something was wrong with Maggie the moment she arrived at the veterinary clinic.  She held her head low and stepped slowly and tentatively – not the same perky young Shetland Sheepdog I had vaccinated two weeks ago.

“She was fine for about a week after our last visit,” said Dana Lasser of Oderton, MD, Maggie’s owner.  “Last week, however, her appetite slowly decreased, and she started slowing down and getting weaker.  Today, she stumbled down the stairs, and now she can barely walk af few steps before she has to stop and rest.”

I rushed Maggie into an exam room.  The dog’s gums were white as a sheet, a sure sign of anemia.  I took a blood sample, performed several tests, and came to a diagnosis:  immune-mediated hemolytic anemia.  This type of anemia occurs when the immune system attacks the body’s own red blood cells.  Treatment is difficult, frustrating and often unsuccessful.

“I can’t help wondering if the vaccinations she received could have had something to do with her anemia, “Lasser says.

Experts question whether vaccinating too often creates more risks than benefits.

Vaccinations probably have done more for the health of dogs than any other veterinary advances.  The lifespan of pets today is largely the result of our control over preventable diseases.  However, as veterinary-immunology developments emerge and side effects associated with vaccination become apparent, veterinarians and their clients have begun to question the need for yearly boosters.

Option vs. necessity

It’s difficult to say which canine vaccines are necessary and which are of limited or no value.  The American Association of Feline Practitioners, in conjunction with the Academy of Feline Medicine, issued vaccination guidelines that also can be applied to dogs.  They divide vaccines into two groups:  core and non-core.  Core vaccines are those every animal needs.  Non-core vaccines are those to be considered based on various factors, including the risk of disease exposure, disease severity, the efficacy and the safety of the vaccine, and clien-specific concerns such as cost and convenience.

Most veterinarians agree every dog should be vaccinated against rabies, distemper, adenovirus (infectious hepatitis) and parvovirus.  Some also list parainfluenza and bordetella (kennel cough) among core vaccines.  Vaccines against coronavirus, Lyme disease, leptospirosis and giardia are generally considered non-core.

Commonly, dogs receive vaccinations throughout life if the disease for which the vaccine protects can affect the animal at all stages of life and if the immunity produced by the vaccine is short-lived.

However, recent research has shown dogs vaccinated against the canine distemper virus as puppies, for example, develop antibody levels that persist for many years.  Studies on dogs vaccinated against parvorirus have shown that immunity to this potentially fatal disease lasts several years and may be lifelong in some instances.

Rabies is the most important core vaccine due to the fatal nature of the disease in animals and it’s human-health implications.  Public health authorities set frequency standards for rabies vaccination.  Many studies have shown the three-year rabies vaccine induce immunity.

Some vaccinations offer immunization for three years.

The fact that the duration of immunity for most core vaccines is three years (and often much longer) has led many veterinary universities to change their vaccination  protocols.  Private veterinarians also have begun to embrace these changes.

The Bad with the good

Any vaccine can induce adverse reactions, including local pain and swelling, hives, fever, lethargy, and decreased appetite.

But, serious side effects are uncommon.  Avoiding vaccination is not an option.  The goal is to vaccinate more dogs, less often.

Maggie’s distemper vaccine might have caused or accelerated her anemia.  A 1996 University of Pennsylvania School of Veterinary Medicine study documented a relationship between vaccination and immune-mediated hemolytic anemia in dogs.

Maggie was lucky.   After hospitalizations and two blood transfusions, her condition improved.  I am monitoring Maggie closely, and Lasser and I are working together to figure ou the best vaccination schedule.  I don’t ever want to through this again, Lasser says.

Arnold Plotnnick, DVM, is vice president of animal health for the American Society for the Prevention of Cruelty to Animals in New York.