Categories: vaccinations

Are cat vaccinations really necessary?

Photo in public domain – words and highlights added by PoC.

The word necessary means ‘essential’. So are cat vaccinations really essential? You cannot say that cat vaccinations are essential. This is because they are not without risk but if you asked 100 cat owners if they believed that vaccinations are a wise choice, 90% would say yes. But, as is the case with the child MMR vaccine, there is a percentage of cat owners who are suspicious about vaccines and worried that they might hurt their cat. Perhaps more needs to be done by vets to (1) do more research and thereafter (2) be more transparent about the risks.


Rather than being necessary or essential it is impossible to deny that it is very sensible to vaccinate your cat against the usual feline infectious illnesses. This is because vaccines help prevent illnesses and in general they prolong life. Also, in general, vaccines make cats happier because being ill makes you miserable.


I have been particular in saying ‘in general’ because there will be cats who develop fibrosarcoma at the site of the vaccination and repeated multiple vaccinations could lead to the development of cancer in some cats. So for some individual cats the vaccination was catastrophically bad for them.
However it should be stressed that vaccine-associated sarcoma in cats is still very rare. It is said that the occurrence is 1 in 1,000 to 10,000. But I think it is fair to say that even today, in 2019, vets and scientists have not got a handle on the degree of risk of vaccinations. This is the worry for cat owners and it certainly prevents one arguing that they are necessary. The risk element is amply demonstrated in the fact that guideline say that the vaccine should be injected in the leg so that cancer forms there the leg can be amputated (see header image).

This is the risk-reward formula. The whole point of feline and human vaccinations is that the rewards are greater than the risk of being hurt by the vaccine. Therefore the sensible cat guardian vaccinates their cat. It is logical but it is not necessary.

For instance there are circumstances whereby a cat is protected from illnesses by the vaccinations of other cats. Say a cat lives in area where all the other cats are thoroughly vaccinated. This creates a dead zone in the neighborhood where the diseases that the vaccines prevent are not present. If one unvaccinated cat is introduced into this area she is protected against these illnesses by the other vaccinated cats. That’s just a rather crude example of where a vaccine is less important than for another cat in a much more contagious area where she is surrounded by diseased cats. Under these circumstances you could argue that cat vaccinations are necessary. Another example where vaccinations are less important is for full-time indoor cats living alone. Although in the US a rabies vaccine is mandatory.

Times have changed

In the past vets believed that vaccination was an entirely safe procedure. They did not suspect that vaccinations could cause disease as well as protect against them. Back in those days it would be hard to argue that vaccinations were anything other than necessary.

They have learned that there is a risk as mentioned above and the more immediate anaphylactic shock. It seems that the experts are not sure why vaccines can cause these diseases. One possible reason is the added adjuvant (immune booster substances) while another is the FeLV and rabies vaccinations.

One 2011 study made this statement in their summary:

“In particular, aluminum in adjuvant form carries a risk for autoimmunity, long-term brain inflammation and associated neurological complications and may thus have profound and widespread adverse health consequences. In our opinion, the possibility that vaccine benefits may have been overrated and the risk of potential adverse effects underestimated, has not been rigorously evaluated in the medical and scientific community.”


The guidelines given to veterinarians on feline vaccinations have evolved over the years to take into account the risks. Cat owners should discuss the risks and rewards with their vet beforehand to enable them to give informed consent to proceeding. Cat owners should always politely challenge their vet. The old-style yearly boosters seem to be a thing of the past and a vet’s ploy to increase business. Vaccinations are not necessary but wise.

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Michael Broad

Hi, I'm a 71-year-old retired solicitor (attorney in the US). Before qualifying I worked in many jobs including professional photography. I have a girlfriend, Michelle. I love nature, cats and all animals. I am concerned about their welfare.

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