Feline Vaccinations: Walking Through the Minefield


Guest Post by Fern Slack, DVM

Vaccination against debilitating and fatal diseases has vastly improved the well-being of humanity. It’s difficult now for us to imagine a world with widespread polio, kids dying daily of whooping cough, or smallpox decimating whole cities. Without our indispensable vaccination programs, such diseases would re-emerge quickly. It does not follow, however, that an individual will achieve better health through more frequent vaccination, nor will the population as a whole. Neither does it follow that the best vaccine plan for a child in, say, South Africa would be the same as for a child in Canada.

Likewise, there is no single vaccine protocol that is right for all cats. Every cat has different risk factors. And while many mistakenly believe that vaccinations are entirely safe, and entirely effective, neither is true. There is always a risk of adverse events associated with vaccination, which must be balanced against the benefit, if any, from a vaccine for your cat. Yet the serious and often fatal diseases we fight with vaccines are still out there.

The Diseases Most Cats Should Be Protected Against

Panleukopenia (“Feline distemper”) used to be a common veterinary hospital visitor, highly contagious and commonly fatal. The virus is a resilient organism which can sneak into your house on your clothes or shoes. Indoor cats must therefore be protected.

The “distemper” combination vaccine includes antigens for Feline Viral Rhinotracheitis and Calici virus. While rarely fatal, both diseases cause much easily preventable suffering.

Indoor cats must also be protected against Rabies. It is contagious to humans, and is nearly 100% fatal if not treated immediately. Cats are very susceptible to it. Vaccination laws are strong, as they should be, to protect the citizenry. Fortunately, there is a feline vaccine available that utilizes a unique technology which delivers excellent protection with minimal inflammation. If other, unnecessary vaccines are eliminated, the repeated administration of such a relatively innocuous one can be better tolerated.

Only these two vaccines, the Rabies and the Panleukopenia /Calicivirus / Viral Rhinotracheitis combination, are recommended by the American Association of Feline Practitioners for all cats, including those living completely indoors.

Other Available Vaccines

Feline Leukemia (FeLV): The FeLV vaccine is worthwhile, but only for cats who spend time outside or have other lifestyle factors that put them at risk, such as living with another cat who has the Feline Leukemia virus. Even then, the level of protection against a strong challenge in a vaccinated cat is far from perfect.

Feline Immunodeficiency Virus (FIV): FIV is not a significant risk for most cats, because contagion nearly always requires a bite wound. It should be used only for cats at demonstrable risk, such as outdoor cats who fight. This vaccination induces antibodies that can’t be differentiated from those produced by actual infection, so a vaccinated cat will always test positive, complicating identification of cats who actually have the disease. This is not a vaccine to be used lightly.

Chlamydophila felis: A nearly useless vaccine which is included as a fourth ingredient in many of the commercially available “distemper” vaccines. The addition distracts the cat’s immune system from the other three, much more important antigens, while engendering nearly no effective protection itself. Unless there is a specific, test-confirmed need for it, this should not be used.

Feline Infectious Peritonitis (FIP): There is no measurable benefit from this vaccine for almost any pet cat, but it still poses all the risks of the “good vaccines”. Avoid this one entirely.

Serious Risks Associated With Vaccination

Vaccine-Associated Fibrosarcomas: Also known as injection site sarcomas, these are very malignant cancers which arise at the site of an injection. The incidence is estimated at between 1 in 1,000 to 1 in 10,000 vaccinations. These tumors must be treated extremely radically. For this reason, some vets now administer feline vaccines as far down the legs as possible, and sometimes even in the tail. Should tumors occur, amputation of a limb can save the cat’s life.

Inflammatory Insults: Much worse and probably more common is the danger deriving from repeated inflammatory insults. Many leading scientists now believe that vaccinations induce systemic inflammatory responses, which can lead to chronic inflammatory diseases such as arthritis, pancreatitis, and inflammatory bowel disease, as well as hyperthyroidism and numerous others. The actual risk for a given cat is likely to be closely proportional to how many vaccines he receives over his life.

Anaphylactic Reactions: True anaphylaxis is quite rare, but does happen. Even with immediate treatment, death may ensue.

Vaccination can cause many lesser problems such as itching, hives, lethargy, vomiting, diarrhea, and local hair loss, to name a few. Most of these are transitory, and are not serious health risks.

Protection With Minimal Vaccination

Where possible, I recommend replacing annual or triannual vaccination with annual blood tests, also known as titer tests, which measure antibody levels. If the titer is insufficient, and if there are no contraindications, I may recommend revaccination. There are admittedly flaws in the concept of titering. Most importantly, we don’t accurately know what level of antibody is protective. Our evidence comes more from experience than from studies. But that is changing, and hopefully there will be more reliable evidence to work with in the future.

Panleukopenia vaccinations induce an enduring immunity in most cats. Many will carry a protective level of antibody for most of their adult life after only kitten shots and one adult injection. Repeated vaccinations are usually not needed. Some Panleukopenia vaccines are approved for 3-year intervals, but even that is more than is needed for most cats. Titering is an excellent alternative for this disease.

There are titer tests available for Feline Viral Rhinotracheitis and Calicivirus also; single-ingredient vaccines can be given should your cat pass one titer and fail another. Some of these can also be given as drops into the eyes and/or nose. The lack of a “shot” reduces the risk of an injection site sarcoma.

The Best Of Both Worlds

Indisputably, every vaccination is an inflammatory event, and all inflammatory events have a systemic component, ripples from the stone thrown in the pond. These insults may be small, but they add up, and so vaccinations should be kept as few as possible. But don’t throw the baby out with the bathwater; a choice to avoid vaccines entirely leaves your cat at risk for some pretty horrible awful diseases. Vaccines are not all good or all bad. They are tools to be used with good judgment for the right purposes. The best vaccine plan for your cat will balance on the tightrope between disease risk and vaccine risk. A good feline vet will take the time to learn about your cat’s lifestyle and history, and then help you learn about the risks and benefits of the vaccination choices to be made for your cat.

Dr. Slack graduated from the College of Veterinary Medicine at the University of Georgia, and has been working exclusively with cats since 1993. She is the owner of Uniquely Cats Veterinary Center in Boulder, CO.

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