Pet vaccinations—too much, too often?

By Sunny Branson

Lenny, a one-year old Bernese mountain dog, was surrendered by his owner to the animal rescue where I volunteer. A bouncy, playful pup, Lenny was up for his standard vaccination booster. Three days after getting the booster, Lenny had a high fever, was lethargic, stiff, and stopped eating and drinking.
by Sunny Branson
Pet_vaccines_b_0508.jpgLenny, a one-year old Bernese mountain dog, was surrendered by his owner to the animal rescue where I volunteer. A bouncy, playful pup, Lenny was up for his standard vaccination booster. Three days after getting the booster, Lenny had a high fever, was lethargic, stiff, and stopped eating and drinking. The veterinarian thought it was a virus and suggested letting it run its course. When Lenny’s condition worsened, a second opinion was sought and tests revealed that Lenny had meningitis.

Lenny lost 15 pounds and could barely lift or turn his head. It was six weeks before any improvement, but he finally made a full recovery. The pup gained all his weight back and soon returned to his playful self. Lenny’s illness put him past due for his next set of vaccinations, so as soon as he was healthy enough, he was boosted once more. Within three days, meningitis set in again putting him down for another two weeks.

There is no proof that the vaccinations triggered Lenny’s meningitis, although there are enough cases like this that many vets conclude that vaccinating susceptible animals may trigger an immune-mediated meningitis.

An estimated 600,000 pets a year suffer from adverse reactions to vaccinations. This is a relatively small number compared to the tens of millions of animals getting vaccinated every year, but there are certainly risks.

Pet owners find comfort in giving their pets vaccinations to protect them from life-threatening diseases such as bordetella, distemper, parvovirus, feline leukemia, and rabies. For example, distemper used to kill nearly half the dogs born; now in the United States it has been greatly reduced by widespread vaccination—some reports state that less than 2% of dogs now get the disease.

The purpose of vaccines, of course, is to boost the animal’s immune system so that it can fend off diseases. But are we vaccinating our pets too much? And are we actually causing harm by over-vaccinating our pets?

The major veterinary associations now agree that vaccinations can trigger all sorts of maladies, from immune diseases to cancer.

Kittens and puppies

Kittens and puppies don’t have strong enough immune systems to ward off infection. The mothers produce milk rich in antibodies. As the babies suckle, they take in their mother’s immunity. While maternal immunity is present in the kitten or puppy’s system, any vaccines given will be inactivated.

The tricky bit is that the duration that these maternal antibodies stay in the system varies with every kitten or puppy. It can depend on the birth order of the babies, how well they nursed, and a number of other factors. After 16 to 20 weeks of age, all the maternal antibodies are gone, and the baby must survive on its own immune system.

Vaccines will not take hold until the maternal antibodies have sufficiently dropped. Because the maternal antibodies wear off at different times, waiting until the baby is definitely free of its maternal immunity may leave a large window of vulnerability. To give the babies’ systems the best chance of responding, vaccinations are recommended intermittently (usually at 8, 12, and 16 weeks old) in hope of gaining some early protection.

Adult pets

Most vet clinics recommend annual revaccinations for adult dogs and cats. However, many vaccines stay in an animal’s system for a number of years, sometimes for its entire life, so with some vaccines, annual boosters can place unnecessary stress on an animal’s immune system.

Pet_vaccines2_Lenny.jpgA study of 1,200 dogs completed by W. Jean Dodds, DVM, demonstrated that one to two years after the initial immunization, 94.4% of the dogs still had adequate immunities to parvovirus, and 97.3% were still protected against distemper. Some dogs were tested as long as six years after the vaccination with similar results.

In Salt Lake City, David Benson, DVM, of Brickyard Animal Hospital says his hospital’s policy is yearly vaccines for adult dogs and cats; however, he personally prefers the three-year vaccination protocol now being suggested in veterinary journals and at conferences.

“Until the vaccine companies label their vaccines for three-year protocols through Duration of Immunity (DOI ) studies, we will continue to recommend the annual vaccinations to our patients,” says Benson. “Suggesting something other than the manufacturer’s recommendation is considered going ‘off label’ and becomes too much of a liability without a signed consent form from the pet owner.”

The only vaccine required by the FDA to have a DOI study is the rabies vaccine; the rest are all voluntary. Most vaccine manufacturers don’t voluntarily do the studies because they are expensive and labor-intensive.

Benson believes clients have a legal and ethical right to know the relative benefits and risks of vaccines so pet owners can make informed choices regarding their animals’ medical care. He gives clients his personal recommendation but always offers a verbal disclaimer so they know his advice is not backed by the FDA or vaccination manufacturers.

Also in Salt Lake City, Laura McLain, DVM, of Central Valley Emergency Veterinary Hospital says the hospital’s policy is to give the standard vaccinations every year for three years, then every third year after that. However, this is not what she practices for her own pets.

“There’s a huge debate about vaccinations in veterinary medicine,” says McLain. “The duration of immunity for most vaccines is certainly longer than one year, but we don’t really know how long. My animals are all older – eight to 13 years old – and they had annual vaccines when they were younger. But now, it’s likely my animals are immune to the viral diseases. I still vaccinate them against bordetella every six to 12 months.”

When asked about changing the standard vaccination protocol for adult pets, McLain says, “We still see a ton of preventable diseases, most notably canine parvovirus. For the individual couch-potato poodle, yes, we can probably cut back on vaccines, but for the population as a whole, we still need to encourage basic vaccinations.”

The new guidelines

McLain worked with Ron Schultz, DVM, at the University of Wiscon­sin School of Veterinary Medicine, an ex­pert in the canine immune system who was instrumental in many of the recent changes in vaccine guidelines made by the Amer­ican Animal Hos­pi­tal Associ­ation (AAHA) and the World Small Animal Veterinary Association. 

Pet_vaccines3_0508.jpgAlthough he agrees with the vaccination guidelines in place for puppies, adult dogs are a different matter. For adult dogs, he suggests that veterinarians place vaccines in one of two categories: core or non-core. 

The categories are to segregate the vital vaccines from the more discretionary. The core vaccines to prevent high-risk, highly contagious and potentially fatal diseases—rabies, parvovirus, canine hepatitis, and distemper—are to be administered once every three years. The non-core vaccines—bordetella, parainfluenza, lyme, and leptospirosis—are recommended at the veterinarian’s discretion for at-risk dogs and would follow an annual schedule.

Schultz encourages veterinarians to look at the science behind the vaccines and to develop rational, effective vaccination protocols for their clinics. He says the new canine guidelines are “much less controversial” than the previously released guidelines.

Other vaccinations didn’t make the cut at all with Schultz and the taskforce. A third classification recommends no vaccinations against giardia (vaccine not proven to prevent infection), coronavirus (disease isn’t significant), and canine adenovirous-1 (vaccine can cause visual impairment).

Some corporate practices ignore the guidelines altogether because of lost revenue. Schultz is not surprised to learn that some veterinarians are ignoring the recommendations as well. According to vaccine critics, profits are at the root of the profession’s resistance to update its protocols. Without the lure of vaccines, pet owners might be less inclined to make yearly veterinary visits.

A survey by the AAHA shows that fewer than 7% of veterinarians have updated their vaccination recommendations, despite the fact that most of these new recommendations have been published in every major veterinary medical journal since 1995. Many won’t make the change until the FDA gives its seal of approval to update the labels.

“The label means nothing,” Schultz says. He notes that vaccines licensed for one year and three years are often the same product. “The label has an arbitrary and capricious annual revaccination requirement, and it takes an act of Congress to take it off.” Schultz says the Department of Agriculture has applied to remove the language, but to do so is a legislative process that he estimates will take seven years.

For other veterinarian clinics and hospitals, it’s just not economically feasible to stop annual vaccinations. Vaccines add up to 14% of the average practice’s income, the AAHA reports, and veterinarians stand to lose big.

What’s the solution?

Some vaccine manufacturers are trying to develop vaccines that will have fewer adverse effects. For example, Merial has a recombinant feline rabies vaccine that should decrease the tumor risk.

Instead of pushing for annual vaccinations, some clinics try to get patients on a rotating schedule—rabies one year, parvo the second, distemper the third—so that there is still incentive for pet owners to come in for an annual physical exam. The annual exam is still very important. Many people aren’t even aware of all that goes on here, but most vets use this opportunity to check out the full health of the animal including a physical exam, fecal exam, heartworm test, dental exam, nutrition review, blood panels, and even spaying or neutering when necessary.

Instead of defaulting to annual vaccines, some clinics suggest annual titer testing. Titer testing is a blood test to check whether the animal is still protected against the diseases it was vaccinated for.

However, titer testing isn’t always an option for pet owners as the cost is sometimes five times that of vaccinating. Not only is it expensive, but confusing. There are no clear standards as to what constitutes a sufficient titer. Each laboratory will have different cut off levels, and what may be a protective level for one animal may not be the same for another.

The best way to help your pet is to be informed and make knowledgeable decisions about the health of your animal. If your veterinarian is still requesting annual vaccinations, ask questions. Your vet may present you with options. At Central Valley, McLain says, “If clients are concerned, we will offer alternate protocols tailored specifically to the individual animal’s needs.”

Sunny Branson volunteers for Wasatch Animal Rescue, and sponsors two pot-bellied pigs at Ching Farm Sanctuary.

For more information about most recent AAHA guidelines: (2006, revised in Feb 2007 to include new information about parvovirus and distemper vaccinations)

This article was originally published on May 4, 2008.