Rethinking the Canine Vaccination Schedule

Dog Fancy Magazine

June 2003

A faithful dog lover, Arlene Caliendo of Villa Park, Calif., didn't hesitate to give her dogs their annual vaccination boosters. It was just something she did unquestioningly to ensure proper health care for her beloved companions.

But when Caliendo's third adopted Greyhound came with a blood serology, or "titer," test illustrating adequate antibodies protecting her against diseases such as canine parvovirus (parvo) and canine distemper virus (distemper), she was introduced to the controversy of booster shots.

Few issues in the veterinary world have birthed such debate as has the one surrounding annual canine vaccinations. No one disputes that vaccines are, for the most part, safe medical procedures necessary to stave off dangerous and oft-fatal diseases. Every dog needs to have it's initial "puppy shots" to establish baseline immunity.

But now many veterinarians recognize that dogs may be vaccinated too often and thus suffering adverse affects such as autoimmune diseases and chronic allergies. Evidence mounts that immunity from initial vaccines may last longer than previously believed, and giving too many booster shots may cause more harm than good.

"There's no doubt the frequency of diseases for which we vaccinate did go down," says Dr. Larry Glickman, VDM and professor of epidemiology at Purdue University School of Veterinary Medicine in West Lafayette, Ind. "But there's no doubt we have increased the frequency of other diseases [such as lupus and arthritis]."

A recently released, groundbreaking report issued by the American Animal Hospital Association Canine Vaccine Task Force recommends that for the core vaccines–rabies, distemper, parvovirus and canine adenovirus–boosters can be given every three years instead of yearly; this is due to mounting evidence that immunity may be longer lasting than once believed.

Informal studies have shown that approximately 95-percent of dogs retain immunity for many years after administration of a vaccine, says Dr. Jean Dodds, a pioneer in this vaccine debate and a veterinary hematologist and founder of Hemopet in Garden Grove, Calif.

"Vaccination at some point is essential," she says. "But we have to be aware of the adverse reactions. We don't have to give annual boosters [to retain immunity]."

Dr. Michael Paul, DVM and chairperson of the AAHA Canine Vaccine Task Force, notes that the AAHA recommendations are a compromise between too many vaccines and none at all, helping to maintain canine immunity levels without subjecting the dogs to unnecessary medical intervention.

"There's no more 'cookie-cutter' vaccine program," says Paul.

Despite these new recommendations, no concrete, scientific proof exists that explains exactly how long vaccines last and why.

"We'd like science to drive these protocols rather than opinion," said Dr. Donald Klingborg, associate dean for Extention and Public Programs at the UC Davis School of Veterinary Medicine and the former chairperson of the American Veterinary Medical Association's Council on Biologic and Therapeutic Agents.

Both the AAHA and the AVMA stress the need for veterinarians to work with clients to determine the needs of each dog during an annual "well-dog" checkup. In an ideal world, veterinarians would be informed about the latest in vaccine news, spend time with their clients learning about the individual dog's lifestyle and then tailor-make a vaccine program for it.

"A single [vaccine] protocol eliminates that responsibility," says Klingborg. "We [at the AVMA] believe that owners needs to make the decision after consulting with their veterinarian, and a single protocol ignores variations in the animal, vaccines and [lifestyle] exposures."

Risk factors must be evaluated before an immunization schedule is decided upon, say industry officials, because the danger of vaccination might not be warranted in certain circumstances. For example, in geographic areas where Lyme disease is rare, it might not be wise to booster a 12-year-old house-bound Poodle for this disease annually.

WHAT THE AAHA REPORT MEANS

The AAHA report eliminated the canine coronavirus vaccine recommendation due to lack of evidence that the drug offers optimal protection against a rare disease that is mild even in the worst cases. Also listed as "not-recommended" are the giardia lambia booster, which has been found to not prevent the infection, and the canine adenovirus-1, or CAV-1.

Rabies, distemper, parinfluenza, parvovirus and CAV-2 are the "core" vaccines recommended every three years. Vaccine boosters for Lyme, leptospirosis and bordetella are ranked as optional depending on the individual dog, geographical location and lifestyle.

Klingborg believes everyone should sit down and have a heart-to-heart with the veterinarian before deciding when, which and even if boosters are needed.

"It's the vet's job to explain the benefits and risks of vaccinating or not," he says. "Your animal is an individual, and only your vet can sit down and talk to you about [what's best for it]."

WHAT HAPPENS WHEN GET TOO MUCH VACCINE

Vaccines are a medical procedure and, as with any medical procedure, there is inherent risk. Most dogs receive their boosters without any problems, but some encounter allergic reactions, local pain or swelling.

What's alarming to many veterinarians is evidence that in some rare instances, vaccines stimulate the dog's immune system, triggering it to respond against its own tissues. This results in blood, joint, nervous system or skin diseases that sometimes don't crop up until weeks or even months after the vaccination, making it difficult for vets to forge a link between shot and sickness.

Repeated vaccines throughout the years can cause dogs to produce antibodies against their own tissue, Glickman and his colleagues theorize. If vaccines are given to a sick or chronically ill dog, this effect can be compounded. A dog stands the chance of being overwhelmed by the virus found in the vaccine, compromising an overworked immune system and creating more problems.

Dr. Karen Hoffman, VMD, at the Bethel Mill Animal Hospital in Sewell, NJ., says she sees numerous cases of ear infections, allergies, hemolytic anemia and thyroid ailments–infirmities she chalks up to too many unneeded vaccinations.

"Don't overstress the immune system," she says.

WHAT OPTIONS ARE THERE?

Dodds is a firm believer in titer tests, or blood tests used to measure the amount of antibody protection in a dog's bloodstream. If high levels of antibodies are present–either from past vaccines or from natural immunity due to exposure–the dog is considered protected from certain diseases. Low antibodies may mean that animal is at risk for infection.

But some veterinarians argue the effectiveness of titers, claiming that a low titer does not mean the dog does not have immunity, since some dogs are still immune even if their blood levels don't show high levels. It costs more to titer (approximately $50 versus $8 for the vaccine), and the lack of clinical continuity in interpreting the lab results presents a quagmire for vets striving for uniformity.

"Titers don't necessarily tell you everything you need to know," says Klingborg. "I think it's wrong to say 'use titers for general immunity'."

Other veterinarians don't place much emphasis on the value of titers and instead lean toward vaccines.

Yet Dodds claims titers are an admirable tool, offering vets and dog owners valuable information without undo risk.

"If it's safer overall, it's a better [choice]," she says.

Adds Hoffman: "All people who love their pets and want to do the best thing for them, I tell them to titer."

Above all, dog owners must discuss the vaccine issue with their veterinarians so together, they can reach a healthy compromise.

That's exactly what Caliendo did at her next appointment with Dr. James Watson of the Villa Park Animal Clinic in Villa Park, Calif. Together, they discussed the lifestyles and health concerns surrounding her three Greyhounds–King, Sassy and Kandy–and they settled upon a three-year interval for rabies and the DHLP booster. This is a four-in-one vaccine that contains the antigens for distemper, CAV-2 (canine hepatitis and respiratory infection), leptospirosis and parainfluenza. The rest of the vaccines, such as the ones for parvovirus and bordetella, will be on the traditional schedule for now.

"This was something we both agreed upon," Caliendo says. "I'm happy with it. I did not want to over-vaccinate, yet I wanted to make sure all my bases were covered. In the middle there, I feel comfortable with that."

Dr. Dennis Cloud of the Cloud Veterinary Center in O'Fallon, Mo., is also assuming a middle-of-the-road approach.

Like Caliendo, other dog owners should talk to their veterinarian about vaccine schedules, as well as about the dogs' lifestyles, health issues, future travel plans and geographical considerations. For example, if parvo is prevalent in the local area, annual boosters might be best for that individual animal, despite the new recommendations. As listed in the AAHA report, no two dogs are alike and thus no two vaccine schedules should be alike, as well. They must be tailored to the needs of the individual patient, the report states.

Even if dog owners adopt a tri-annual vaccination schedule, they must visit their veterinarians for annual canine health checks to answer questions, re-evaluate vaccine plans, do blood work if requested and just make sure all is operating smoothly.

"We taught people that vaccines were so important, and that's all they had to do," says Paul. "Yet the most important thing is for the owner to [talk to the vet] about the little changes that may be significant."

During the annual check-ups, clients can also request titers to determine the levels of antibodies in dogs older than one year before making a booster decision. The TiterCHEK test, from the San Diego, Calif.-based Synbiotics Corp., is the first in-office titer test licensed by the USDA for use in veterinary clinics. It takes approximately 15 minutes to process and Dodds has said the majority of dogs titered will indicate a satisfactory immune response, making the need for boosters non-existent at that time.

If patients choose to titer instead of vaccinate, and they are required by a boarding kennel or an obedience class to show proof of up-to-date vaccines, they can request a letter from their veterinarian stating proof of immunity, says Paul.

"We all want to do the best things for our pets," he says. "To be vaccinated appropriately, not defensively."