Schultz: Dog vaccines may not be necessary
March 14, 2003
Once a year, Ronald Schultz checks the antibody levels
in his dogs’ blood. Why? He says for proof that most annual vaccines are
Schultz, professor and chair of pathobiological
sciences at School of Veterinary Medicine,
has been studying the effectiveness of canine vaccines since the 1970s; he’s
learned that immunity can last as long as a dog’s lifetime, which suggests that
our “best friends” are being over-vaccinated.
Based on his findings, a community of canine vaccine
experts has developed new veterinary recommendations that could eliminate a
dog’s need for annual shots. The guidelines appear in the March/April issue of
Trends, the journal of the American Animal Hospital Association (AAHA).
Every year, when we take our dogs to the
veterinarian’s office, they could receive up to 16 different vaccines, many of
which are combined into a single shot. Four of these products protect against
life-threatening diseases, including rabies, canine parvovirus type 2 (CPV-2),
canine distemper virus (CDV) and canine adenovirus type 2 (CAV-2); the rest
protect against milder diseases to which only some dogs are exposed, including
But, as many veterinarians are realizing,
over-vaccination can actually jeopardize a dog’s health and even life. Side
effects can cause skin problems, allergic reactions and autoimmune disease.
Though the case in cats, not dogs, tumors have been reported at the site of
“These adverse reactions have caused many
veterinarians to rethink the issue of vaccination,” says Schultz. “The idea
that unnecessary vaccines can cause serious side effects is in direct conflict
with sound medical practices.”
For 30 years, Schultz has been examining the need to
vaccinate animals so often and for so many diseases. “In the 1970s, I started
thinking about our immune response to pathogens and how similar it is in other
animals,” says Schultz. “That’s when I started to question veterinary
Just like ours, a canine’s immune system fires up when
a pathogen, like a virus, enters the body. The pathogen releases a protein
called an antigen, which calls into action the immune system’s special
disease-fighting cells. Called B and T lymphocytes, these cells not only
destroy the virus, but they remember what it looked like so they can fend it
off in the future.
It’s this immunological memory that enables vaccines,
which purposely contain live, weakened or dead pathogens, to protect against
But, as Schultz points out, vaccines can keep people
immune for a lifetime: we’re usually inoculated for measles, mumps and rubella
as children but never as adults. So, can dogs be vaccinated as pups and then
While evidence from Schultz’s studies on both his own
dogs and many other dogs from controlled studies suggests the answer is yes,
Schultz recommends a more conservative plan based on duration of immunity and
Schultz says that core vaccines, or the ones that
protect against life-threatening disease, are essential for all dogs, yet he
does not recommend dogs receive these shots yearly. “With the exception of
rabies, the vaccines for CDV, CPV-2 and CAV trigger an immunological memory of
at least seven years,” he explains. (Studies testing the duration of immunity
for rabies shots show it lasts about three years.)
For these reasons, Schultz suggests that dogs receive
rabies shots every three years (as is required by law in most states) and the
other core vaccines no more frequently than every three years.
Some non-core vaccines, on the other hand, have a much
shorter duration of immunity, lasting around one year. But, as Schultz points
out, not every dog should get these types of vaccines, because not every dog is
at risk for exposure.
Today, many vaccinated dogs receive a shot for Lyme
disease. However, Schultz says that the ticks carrying the Lyme disease
pathogen can be found in only a few regions of the United States. More
importantly, Schultz adds, “The vaccine can cause adverse effects such as mild
arthritis, allergy or other immune diseases. Like all vaccines, it should only
be used when the animal is at significant risk.” He notes that the Veterinary
Medical Teaching Hospital at the UW–Madison School of Veterinary Medicine
rarely administers the Lyme disease vaccine.
Another common vaccine that Schultz says is
unnecessary protects against “kennel cough,” an often mild and transient
disease contracted during boarding or dog shows. “Most pet dogs that do not
live in breeding kennels, are not boarded, do not go to dog shows and have only
occasional contact with dogs outside their immediate family,” Schultz
recommends, “rarely need to be vaccinated or re-vaccinated for kennel cough.”
Schultz says that it’s important for veterinarians to
recognize an individual dog’s risk for developing a particular disease when
considering the benefits of a vaccine. “Vaccines have many exceptional
benefits, but, like any drug, they also have the potential to cause significant
harm.” Giving a vaccine that’s not needed, he explains, creates an unnecessary
risk to the animal.
Recommending that dogs receive fewer vaccines, Schultz
admits, may spark controversy, especially when veterinarians rely on annual
vaccines to bring in clients, along with income.
But, as he mentions, annual visits are important for
many reasons other than shots.
“Checking for heartworm, tumors, dermatological
problems and tooth decay should be done on a yearly basis,” he says. “Plus,
some dogs, depending on their risk, may need certain vaccines annually.” Rather
than vaccinating on each visit, veterinarians can use a recently developed test
which checks dogs’ immunity against certain diseases.
Schultz adds that veterinarians who have switched to
the three-year, instead of annual, vaccination program have found no increase
in the number of dogs with vaccine-preventable diseases.
“Everyday, more and more people in the profession are
embracing the change,” notes Schultz. And, that the new vaccination guidelines
supported by the AAHA, along with the task force members representing the
American Colleges of Veterinary Internal Medicine, Veterinary Microbiology and
the American Association of Veterinary Immunologists, is evidence of just that.
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