contributed by:
Michael List, D.V.M.

IMPORTANT INFORMATION ABOUT FELINE ANNUAL VACCINATIONS

In the past few years, cats across the country have developed tumors in sites on their bodies where they received vaccinations. These reactions are rare­the current estimate is one in several thousand vaccinated cats. The tumors do not spread (metastasize) to distant areas of the body, but they do expand locally and can be difficult or impossible to remove permanently. Although your cat¹s chance of developing life-threatening disease if left unvaccinated is probably greater than the chance of experiencing one of these reactions, we feel we should inform you of this risk.

WHICH VACCINES ARE INVOLVED?

It appears that both Rabies and Feline Leukemia vaccines can cause these reactions. The Feline Distemper/Upper Respiratory combination, which we call "PCRP", does not seem to be involved.

DOES YOUR CAT REALLY NEED THESE VACCINES?

RABIES--Annual vaccination against Rabies is required by Indiana law.

FELINE LEUKEMIA--Unprotected cats who can come in contact with Feline Leukemia-infected cats directly or even through window screens are at risk of developing fatal disease. If you are certain that your cat will never encounter an infected cat, perhaps he or she does not need this vaccine. Feline Leukemia vaccine has been available for over a decade, and with it we have made great strides in preventing the disease. But it is still a very significant cause of feline death in this community, and, considering comparative risks, it would be very difficult for us to recommend against using the vaccine in any cat, even those who have minimal chances of being exposed.

DOES YOUR CAT REALLY NEED ANNUAL BOOSTERS?

This is perhaps the hardest question to answer. Although cats' habits, particularly as regards hygiene, must create greater risk for exposure to disease than that experienced by humans, one must wonder if annual boosters are absolutely necessary. The data on which the vaccine manufacturers¹ recommendations are based have all been generated by those same manufacturers' research. Without hard facts to indicate that the immunity conferred by the vaccines lasts longer than one year we have no scientific grounds for making alternate recommendations and must continue to recommend annual revaccination as per standard veterinary practice.

WHAT SHOULD YOU WATCH FOR?

Not all vaccination reactions become tumors. However, if your cat develops any lump, particularly on the thighs or flanks, please let us know immediately. Early removal of areas of suspected vaccine reaction is our best tool to combat the tumors that sometimes form.