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Animal vaccinations

Without question, vaccination has been one of the most important interventions in disease prevention that has ever been developed. In spite of the demonstrable, and ongoing, success of vaccination, a small, but vocal, anti-vaccination movement has developed in human medicine, occasionally buttressed by horrifying instances of adverse reactions, as well as the occasional publications in scientific journals (vis, the Wakefield debacle). Vaccine development continues, and human health continues to benefit, as new vaccines are developed and tested prior to release.

In veterinary medicine, vaccination has also proven to be a boon for animal health. Diseases such as canine parvovirus and canine distemper, feline leukemia, or equine tetanus, have been greatly reduced – in some cases, nearly eliminated – by vaccination. And, as in human medicine, a small, but vocal, anti-vaccination movement has developed, regaling fearful listeners with tales of acute harm, or chronic, low-grade disease (sometimes termed “vaccinosis”).

Yet, in spite of the success of animal vaccination, genuine questions remain as to ideal intervals for booster vaccination. That is, although the effectiveness of vaccination can be shown by reduction in disease, as well as the occasional challenge study (where vaccinated animals are exposed to disease-causing organisms to see if they are protected), no one really knows the “optimum” interval for giving boosters of most animal vaccines.

There are several reasons for this. First and foremost is the fact that animal vaccinations are not subjected to the same rigorous pre-market testing that is required for the release of a human vaccine. Otherwise stated, animal vaccines can be released without large, controlled challenge studies that are necessary prior to the release of human vaccines. Animal vaccines are controlled by the US Department of Agriculture, which merely requires that vaccines be shown to be safe and pure, and have a “reasonable expectation” of efficacy prior to their release; however, the clinical need (relevancy) or usefulness (applicability) of a particular vaccine may not necessarily be assured by the licensing process.

Historically, many animal vaccinations have been given annually. These recommendations were based on the best available knowledge at the time. As research has continued, it appears that some vaccines may protect animals from disease for longer than was previously felt. This information has been incorporated into some vaccine guidelines, e.g., many rabies vaccinations are now given every three years, instead of annually. Still, in spite of good data, new recommendations are not always adopted in a timely fashion, for a variety of reasons, which might include difficulty in disseminating the information, as well as practitioner comfort with schedules that have been effective at disease prevention in the past. Unfortunately, some people have claimed that practitioners resist giving vaccinations less frequently simply due to a profit motive; this assertion is outrageous, and obscures the many difficulties veterinarians face in coming up with an “ideal” program to fit every animal.

As such, it is essentially impossible to make firm, science-based guidelines when it comes to animal vaccination. It is almost without question that “some” vaccination helps prevent animals from disease; it is also almost without question that “no” vaccination puts animals at risk for disease, especially when such animals have contact with other animals; it is fortunate that if animals are vaccinated more frequently than needed to provide protection from disease, there is, in general, little apparent harm. That said, when harm can be shown, it is investigated, e.g., the problem of vaccination-related sarcomas in felines. As a result of such investigations, newer protocols, and newer methods of vaccine administration are being developed.

Unfortunately, there is currently no way to develop an individualized vaccination program for animals that can be said to assure protection from disease and completely prevent adverse reactions. Some people may advocate measuring titers (antibody levels) in the animal’s blood; unfortunately, these levels have not been correlated with disease prevention in animals, that is, having a high titer does not necessarily mean that an animal is protected from disease. Still, one can make some reasonable generalizations, for example, one can be fairly well assured that animals that don’t have contact with other animals may need less vaccination (for example, cats that are kept indoors), or that vaccination of animals at the end of their expected life span may be of less importance. Still, in general, animal owners must currently rely on the experience of individual practitioners, rather than sound science, for vaccine recommendations for their animals.

For more information about animal vaccines, and the vaccine-related controversies, see the Vaccination Principles of the American Veterinary Medical Association, updated in 2007.

Posted in: Vaccines, Veterinary medicine

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28 thoughts on “Animal vaccinations

  1. Jules says:

    Still, in general, animal owners must currently rely on the experience of individual practitioners, rather than sound science, for vaccine recommendations for their animals.

    That’s actually kind of scary, because the personal recommendations vary greatly. I’ve seen four different vets in the past two years (I did a lot of moving around, and the cats needed the attending paperwork), and even within the same practice it’s kind of startling how wide the range of opinions about vaccines, and diets, are. The vet my parents used to use, for instance, recommended shots every year. The vet they use now is a three-year kinda guy. The vet I currently see probably wouldn’t know what to do with a rabies vaccine if you gave her one (but then again, I now live in a rabies-free country).

    Furthermore, vet opinions tend to reflect the general opinion of the area in which they are based, and while most city and suburban practices tend to stay current and give good advice, I’ve heard of some rural practices where the vet in question is, for instance, anti-spay/neuter because it’s “not God’s will” (or similar BS line).

    I’m a member of several online pet communities, and this topic pops up from time to time. I’m pro-vaccine, but even I tend to look askance at the proposition that I vaccinate my indoor-only cats every year. There are a lot of websites that seem devoted to proving that vaccines are the Devil’s toy, and owners post stories about how their dog got sick and died or their cat got injection-site sarcomas. I don’t doubt that a lot of it has to do with the care the pet was receiving beforehand, but let’s face it: if you came upon those kinds of stories while browsing around about pet vaccines, I’m pretty sure you’d be a little nervous, too. ‘

  2. KristinMH says:

    Thanks for covering this. After one of my dogs had an allergic reaction to one of her booster vaccines – her face and nose swelled up; it was scary but didn’t do her any lasting harm – I did some U of Google research and, just like you, Jules, ran into the usual anti-vaccine scaremongering. Fortunately we have a really good, science-based vet who explained the science and recommended going to the three-year vaccine schedule.

    We have two active, outdoor dogs, so they get all the “extra” shots – just every three years instead of every year.

    If anyone doubts the necessity or effectiveness of animal vaccines, I recommend reading the memoirs of James Herriot, a vet working in rural England in the 30s. Read the heartbreaking stories of beloved pets slowly dying of distemper, and the vet’s incapacity to do anything to help, and then make the decision.

  3. KristinMH says:

    I forgot to say that hopefully pet owners searching for information about vaccines will come across this instead of the anti-vax stuff. Good job, David!

  4. DVMKurmes says:

    Unfortunately, some people have claimed that practitioners resist giving vaccinations less frequently simply due to a profit motive; this assertion is outrageous, and obscures the many difficulties veterinarians face in coming up with an “ideal” program to fit every animal.

    That claim would be outrageous if every veterinarian really attempted to honestly evaluate the evidence of efficacy of the vaccines and the individual risks of their patients. Unfortunately I have heard a classmate of mine give that exact reason for not giving 3 year vaccines (including Rabies) and there is another clinic in my area that gives every animal they see annual Rabies vaccinations and cannot give anyone a good medical reason for it. (they also provide acupuncture and chinese herbs).

    I think it is important to point out how much certain vaccines-especially Rabies, protects the human population as well. Before widespread rabies vaccination of pets, up to several hundred people died of Rabies every year in the U.S. And still kills many people in the developing world.
    http://www.ncbi.nlm.nih.gov/pubmed/12075367
    That kind of information makes me think that vaccination is the most important service we can provide to animals and their human owners.

    I have actually run into a couple of people who refuse to give their pets even Rabies vaccinations and will ignore any advice in favor of it, even when Animal control can and will euthanize the animal if it ever bites anyone fortunately that kind of true believer is very rare.

  5. Scepticon says:

    The link given at the end needs some tuning it has http://www.sciencebasedmedicine.org/at at the beginig of the address.
    This might confuse some people.

  6. khan says:

    In many places, state or county law requires yearly rabies vaccines.

  7. David Gorski says:

    Not in New Jersey, where I lived. It required every other year rabies vaccines. Ditto Michigan, where I live now.

  8. DVMKurmes says:

    I think many of the local laws are just out of date and no one has bothered to update them using newer information. The three year vaccines (and a couple of 4 year vaccines) have been documented to be safe and effective for 10-20 years now.
    The CDC publishes national rabies control reccomendations every year and the local governments often do not keep up with these at all.

    http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5702a1.htm

  9. TsuDhoNimh says:

    Just watch “Old Yeller” and tell me rabies vaccines are bad.

    When I lived in Mexico, Guadalajara had a rabies outbreak inside the city limits. The animal control officers were shooting stray dogs and cats on sight. Stray meant “any canine outside a confined area and not on a leash”.

  10. storkdok says:

    Very interesting. I just had this talk with our vet last month. I was curious if the anti-vaccine movement had spilled over into veterinary medicine. She said, “Oh, yes, there is a definite movement, just like the human anti-vaccine movement.”

    I think DVMKurmes makes a very good point about protecting humans from rabies with making sure our pets are vaccinated against it. One of the films I remember from medical school was of a man from Afghanistan who was bitten by his dog, and he contracted rabies. The film showed the course of his disease and his death from rabies. It made an indelible impression on me.

  11. dlmccaslin@yahoo.com says:

    I live in the eastern panhandle of West Virginia, and my vet is in Maryland. He is a great guy, and he impressed me with his use of “woo” as a pejorative. Anyway, He told me that Virginia state law requires rabies vaccines every 3 years, but West Virginia law requires every other year (His words were, “same shot, different stupid law.”)

  12. apteryx says:

    Hey Jules, I have the same concern about vaccine-induced cancer (I have a purebred indoor LOLcat), but at least one of the cat viruses in the standard shots, panleukopenia or feline distemper, is so durable and transmissible that you can pick it up on your shoes while walking through grass and carry it home to your own kitteh. It’s a miserable disease and has a significant mortality rate (kittens exposed in the womb often die or develop permanent ataxia), so I regard this as like polio: the disease is much more to be feared than the vaccine.

  13. mattand says:

    David:

    I came across this article via Phil Plaitt @ badastronomy.com. Thanks for writing this. This is something my girlfriend and I have wrestling with our Boxer (dog, not pugilist). I found the titer info interesting. I’ve been on the fence about titer over vaccination because I wasn’t sure how much anti-vacc info was pushing it.

    We were at a dog fair in Philly where the University of Penn Vet Hospital had set up a booth. IIRC, the docs were recommending the titer test for Lyme disease. Again, take this with a Kong full of salt as I need to re-check my facts.

    @David Gorski: Not sure when you lived in NJ, but I can tell right now that we’re on a 3-year schedule with rabies shots. I’m assuming that’s a state mandate, but it could be local.

    Overall, it’s kind of dispiriting that the Jenny Mc Carthy crap is now affecting our pets as well. Again, thanks for the article.

  14. Joe says:

    apteryx on 14 Jan 2009 at 4:07 pm wrote “… so I regard this as like polio: the disease is much more to be feared than the vaccine.”

    Your ignorance defies description. I grew up in fear of the polio season that began every spring. I have a friend who suffered polio, she has a lot of trouble getting around. The vaccine ended that, and allowed ignoramuses like you to pontificate on subjects about you which you know nothing. Nonetheless, I would not wish you to spend the rest of your life in a wheel chair on an artificial respirator.

    Is there any idea you consider to consider too stupid to promote? I don’t think so.

  15. Joe says:

    Um. I see I read that bassackwards. I apologize. I have no excuse.

  16. apteryx says:

    Maybe “Manichaean worldview”? :)

    The sad part is that we can get more and better vaccines for our cats than numerous African parents can get for their children. I love my cat and do not apologize for spending money on her health, but that is not just. While those of you on this blog are stewing about wealthy white people who do not use as many Western medical services as you think they should, you might spare some concern for the people who have little or no access to such services, and would derive the most benefit if just the most basic things could be provided to them.

  17. Calli Arcale says:

    Oh, we do care about them. I’ve read posts from several of the SBM contributors on their own blogs talking about how tragic it is that anti-vax views and HIV-denialism have taken such a toll on sub-Saharan Africa. There have been cases where governments decided not to spend money to help their people because the government leaders (who were generally not exposed to the diseases themselves) had bought in to the hysteria. The most egregious case is Mbeki in South Africa, denying anti-retrovirals to poor South Africans because he didn’t believe that HIV really caused AIDS.

    While the majority of the problems facing people in impoverished nations are more basic (food, clean water, sanitation, access to basic medical services, logistics, infrastructure, etc), woo is also to blame. Sometimes this is because of denialism, but alternative medicine has a more insidious effect — it’s often a lot cheaper than effective medicine, so it is very tempting for a politician to believe that he could help 5,000 Africans with the same money that would help 50 by conventional medicine. And he goes away believing that he has done good.

  18. Scotty B says:

    Historically, many animal vaccinations have been given annually.

    My first response to this was: “Huh. I thought they were usually injected with a syringe.”
    Then I realized I merely read it wrong. :P

  19. art malernee dvm says:

    As a vet who preaches evidence based medicine ( the discipline that insist on proof traditional medical practices really work) I find it difficult to practice evidence based medicine if I choose to revaccinate adult dogs and cats that I have fully vaccinated as kittens and pups and suspect if pet vaccines were under the control of the FDA i would not be allowed to.

    definition quoted from Alternative Health Measures published by AMA p 5: Fraud: the FDA has defined health fraud as promotion of an unproven remedy for profit.

    I cannot find the USDA definition of health fraud anywhere on the Internet but suspect if they have one it will be a very “organic” definition.

    when i was a kid the vet i worked for called the last serial puppy and kitten vaccine the “final adult shot”. In vet school I was taught from our Current Veterinary Therapy text book that the reason to vaccinate dogs and cats every year is not because the vaccine is needed but to get the pet back every year for a yearly exam. Yearly exams in pets or people is another ripe topic for those who preach evidence based medicine.

    art malernee dvm

  20. Alaskan says:

    “Some people may advocate measuring titers (antibody levels) in the animal’s blood; unfortunately, these levels have not been correlated with disease prevention in animals, that is, having a high titer does not necessarily mean that an animal is protected from disease.”

    True. Although negative titers may have practical clinical significance.

    “Still, in general, animal owners must currently rely on the experience of individual practitioners, rather than sound science, for vaccine recommendations for their animals.”

    Absolutely. A great point that at first sounds counterintuitive but
    makes a lot of practical sense considering veterinary formularies are typically only a starting point for the veterinary practitioner. Published results from a few studies that may or may not match a current condition are no match for a veterinarian’s unpublished direct clinical experience.

    Thanks for your contributions to evidence based veterinary medicine.

  21. mckenzievmd says:

    As a practicing small animal vet, I run into this issue all the time. I agree that the level of evidence available for the duration of immunity is not as high as we’d like, but there is an enormous literature on the safety and efficacy of vaccines in companion animals, and it overwhelmingly supports their use.

    It’s a little bit a case of science-based medicine paying a price for its own thorouoghness and honesty. The discovery of vaccine-associated sarcomas in cats has feuled the anti-vaccine extremists campaign markedly. Yet the fact is that the issue was identified and investigated by vets practicing rigorous scienctific medicine, and the changes in vaccination protocols within the veterinary community were driven largely by good, appropriate scientific questions and skepticism. It’s infuriating that those efforts to improve are taken on as ammunition by the homeopaths and others who seek to undermine the very paradigm that discovered and is trying to reduce something their methods would never have found or done anything about! *sigh*

    Brennen McKenzie MA VMD
    http://www.skeptvet.com/
    http://skeptvet.com/Blog/

  22. art malernee dvm says:

    As a practicing small animal vet, I run into this issue all the time. I agree that the level of evidence available for the duration of immunity is not as high as we’d like, but there is an enormous literature on the safety and efficacy of vaccines in companion animals, and it overwhelmingly supports their use.>>>>
    I think that is a knee jerk reaction from the profession.
    I never did get re vaccinated every 1-3 years with the same vaccine and neither should pets.
    The debate about pet vaccination within the veterinary profession in the last 40 years always has been whether we should be vaccinating based on sound immunological principles or just when it suits us. I am skeptical of anyone in the profession forty years ago that now says we thought vaccines were immunological needed every 1-3 years to maintain immunity. To look back in history now and say vets started to practice astrology because we thought it was best that re vaccination should be based on how long it takes the earth to go around the sun, I think harms the profession more than to fess up and tell the public we started re vaccinating every 1-3 years forty years ago because the laws got changed forty years ago that allow us to do it. If vets and pet owners do not understand why we started to vaccinate every 1-3 years forty years ago they will not understand laws are needed to force us to stop it now.
    art malernee dvm
    The SkepVet#2

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