Canine and feline vaccination programs have been a cornerstone of prevention of infectious disease in pets. Vaccination has been reducing and controlling the spread of infectious disease since vaccines first came into use. Currently, there are several vaccines considered “core” for dogs and cats, which are administered in order to prevent diseases which pose health risks to susceptible animals.

Yearly Vaccinating – Is it Necessary?

The recommendation has been to administer these vaccines yearly so that the majority of animals would be protected, as it was assumed that in some animals the protection would wane over time. Annual vaccination was developed as the most realistic and convenient way to protect the largest segment of the pet population. However, there is little or no data available to suggest that annual vaccination is necessary to impart greater immunity to the vaccinated individual. Yearly vaccination programs have been designed by manufacturers, and efficacy of individual vaccines may vary greatly between vaccine companies, the specific viral disease, the type of vaccine and the challenges an individual animal faces.

These concerns have led to several studies by leading Veterinary Associations and individual researchers attempting to discover the true duration of immunity of vaccines, and reassess the value of annual vaccinations.

The American Veterinary Medical Association’s Executive Board issued a Principles of Vaccination paper in April 2001. In part, it reads,

“The one-year revaccination frequency recommendation found on many vaccine labels is based on historical precedent and United States Department of Agriculture regulation, not on scientific data. Even in those cases where scientific data was submitted to qualify the label claim, the data generated does not resolve the question about average or maximum duration of immunity. There is evidence that some vaccines provide immunity beyond one year. Revaccination of patients with sufficient immunity does not add measurably to their disease resistance, and may increase their risk of adverse post-vaccination events. Vaccination is a potent medical procedure with both benefits and associated hazards.”And further, “Adverse events may be associated with the antigen, adjuvant, carrier, preservative, or a combination thereof. Possible adverse events include failure to immunize, anaphylaxis, immunosuppression, autoimmune disorders, transient infections, and/or long-term infected carrier states. In addition, a causal association in cats between injection sites and the subsequent development of a malignant tumour is the subject of ongoing research.”

The following excerpts are from a letter from veterinarians that was published in the Veterinary Times, UK, January 2004.

“Dear Editor: We, the undersigned, would like to bring to your attention our concerns in the light of recent new evidence regarding vaccination protocol.The report of the American Animal Hospital Association Canine Vaccine Taskforce in JAAHA (39 March/April 2003) is interesting reading: ‘Current knowledge supports the statement that no vaccine is always safe, no vaccine is always protective and no vaccine is always indicated’; ‘Misunderstanding, misinformation and the conservative nature of our profession have largely slowed adoption of protocols advocating decreased frequency of vaccination’; ‘Immunological memory provides durations of immunity for core infectious diseases that far exceed the traditional recommendations for annual vaccination. This is supported by a growing body of veterinary information as well as well-developed epidemiological vigilance in human medicine that indicates immunity induced by vaccination is extremely long lasting and, in most cases, lifelong.’

Further, the evidence shows that the duration of immunity for rabies vaccine, canine distemper vaccine, canine parvovirus vaccine, feline panleukopaenia vaccine, feline rhinotracheitis and feline calicivurus have all been demonstrated to be a minimum of seven years, by serology for rabies and challenge studies for all others.

The veterinary surgeons below fully accept that no single achievement has had greater impact on the lives and well-being of our patients, our clients and our ability to prevent infectious diseases than the developments in annual vaccines. We, however, fully support the recommendations and guidelines of the American Animal Hospitals Association Taskforce, to reduce vaccine protocols for dogs and cats such that booster vaccinations are only given every three years, and only for core vaccines unless otherwise scientifically justified.

We further suggest that the evidence currently available will soon lead to the following facts being accepted:

  • The immune systems of dogs and cats mature fully at six months and any modified live virus (MLV) vaccine given after that age produces immunity that is good for the life of that pet.
  • If another MLV vaccine is given a year later, the antibodies from the first vaccine neutralise the antigens from the subsequent so there is little or no effect; the pet is not ‘boosted’, nor are more memory cells induced.
  • Not only are annual boosters for canine parvovirus and distemper unnecessary, they subject the pet to potential risks of allergic reactions and immune-mediated haemolytic anaemia.
  • There is no scientific documentation to back up label claims for annual administration of MLV vaccines.
  • Puppies and kittens receive antibodies through their mothers’ milk. This natural protection can last eight to 14 weeks.
  • Puppies and kittens should not be vaccinated at less than eight weeks. Maternal immunity will neutralise the vaccine and little protection will be produced.
  • Vaccination at six weeks will, however, delay the timing of the first effective vaccine.
  • Vaccines given two weeks apart suppress rather than stimulate the immune system.

This would give possible new guidelines as follows:

  • A series of vaccinations is given starting at eight weeks of age (or preferably later) and given three to four weeks apart, up to 16 weeks of age.
  • One further booster is given sometime after six months of age and will then provide life-long immunity.

In light of data now available showing the needless use and potential harm of annual vaccination, we call on our profession to cease the policy of annual vaccination. Politics, tradition or the economic well-being of veterinary surgeons and pharmaceutical companies should not be a factor in making medical decisions.

Follow Suit or Stand Against?

It is accepted that the annual examination of a pet is advisable. We undervalue ourselves, however, if we hang this essential service on the back of vaccination and will ultimately suffer the consequences. Do we need to wait until we see actions against vets, such as those launched in the state of Texas by Dr. Robert Rogers? He asserts that the present practice of marketing vaccinations for companion animals constitutes fraud by misrepresentation, fraud by silence and theft by deception.

The oath we take as newly-qualified veterinary surgeons is ‘to help, or at least do no harm’. We wish to maintain our position within society, and be deserving of the trust placed in us as a profession. It is therefore our contention that those who continue to give annual vaccinations in the light of new evidence may well be acting contrary to the welfare of the animals committed to their care.

The Dr. Robert Rogers they refer to is a veterinarian located in Spring, Texas. He has done extensive research on the various illnesses/diseases that dogs and cats are vaccinated for; which vaccines are really necessary, which are not (and can be harmful), and why. He has also developed a suggested timing and schedule for administration. Dr. Rogers was interviewed regarding the over-vaccination debate for an article which appeared in the Wall Street Journal in mid-2002. He has devoted many years to promoting revision of the statutory requirements regarding vaccinations in Texas. The Texas rabies vaccination law was successfully revised in late 2002 based on pressure from the public, certain veterinarians including Dr. Rogers, and other interested parties.

Dr. Rogers has written:

“I would like to make you aware that the American Association of Feline Practitioners, The Academy of Veterinary Internal Medicine, The American Animal Hospital Association, The American Veterinary Medical Association, Council on Biologic and Therapeutic Agents, and 22 Veterinary Schools in North America have changed their recommended protocols for vaccinating cats & dogs. Our knowledge about immunity and the quality of available vaccines has improved greatly over the past seven years.The AVMA Council on Biologic and Therapeutic Agents (COBTA) presented their consensus at the July, 2000 137th Annual AVMA Convention. They focused on the following points:

  • When an annual booster vaccination with a modified live virus vaccine (i.e. Distemper , Parvovirus or Fe Distemper) is given to a previously vaccinated adult animal – no added protection is provided. Modified live virus vaccines depend on the replication of the virus for a response. Antibodies from previous vaccines do not allow the new virus to replicate. Antibody titers are not boosted significantly; memory cell populations are not expanded. No additional protection is provided.
  • Vaccine Manufacturers label claims should be backed by scientific data. There is no scientific data to support label directions for re-administration of MLV vaccines annually.
  • Vaccinations are important for the prevention of diseases. Annual physical exams at the time of vaccination help improve health by the early detection of treatable disease and contribute to the overall quality of life.
  • Vaccines are not harmless. Unnecessary side effects and adverse events can be minimized by avoiding unnecessary vaccinations.
  • Virus drift is small. There are no new parvovirus strains, and the virus in the vaccine has remained essentially the same.
  • Average pets are similar enough in their exposure to infectious disease and in their response to vaccines that we can have a Standard recommended Vaccination Protocol.
  • The AVMA Council for Biologic and Therapeutic Agents COBTA urges the USDA, Center for Veterinary Biologics to revise its standards for the licensing of animal vaccines and the USDA. CVB has agreed that this should be done.
  • Veterinarians need a standard procedure to report adverse events from vaccinations.

This new information has presented an ethical and economic challenge to veterinarians. I think you will agree with me that in the practice of medicine, the emphasis should be on safety, and that no medicine should be given more frequently, longer, or at a higher dose than is necessary.

Some organizations have come up with a political compromise suggesting vaccinations every 3 years to appease those who fear loss of income vs. those concerned about potential side effects. Politics, traditions, or the doctor’s economic well being should not be a factor in medical decisions.”

Medical decisions about vaccines have become more complex. Selecting vaccine products and recommending vaccine programs are among the most complicated of medical decisions facing any veterinarian. The reasons are numerous: continued evolution of our understanding of the immune system; improved understanding of infectious diseases, the strengths and limitations of the biologic regulatory approval process, and of adverse events associated with vaccination. The onus is on every responsible pet guardian to educate themselves on the issues surrounding vaccination, discuss the issues with their trusted veterinarian, and act in the best interest of their animals.