Vaccines and Sarcomas: A Concern for Cat Owners

Those of us entrusted with caring for cats have two basic desires: first, -we wish to help cats by preventing serious disease and death; second, we wish to do them no harm. Achieving both objectives at the same time seems simple enough. Unfortunately, few medical procedures are totally without risk, and sometimes procedures that are normally helpful can cause harm. The possible association between certain vaccines and sarcomas (specific kinds of cancer) is an example.

Is this something new?

Sarcomas are not new, nor are they extremely rare. But in 1991, veterinarians began to notice a higher than expected number of sarcomas occurring on the body in places where vaccines are commonly injected. Since most sarcomas are not linked with vaccines in any way-and those that are associated occur only infrequently - it is very difficult to establish a clear relationship. Veterinary scientists are clarifying the picture, but much more needs to be learned.

So what's being done?

Veterinarians are deeply concerned. Even though vaccine-associated sarcomas are uncommon, the problem is receiving unprecedented attention by veterinarians and feline vaccine producers. The Vaccine-Associated Feline Sarcoma Task Force is a coalition of concerned national veterinary organizations dedicated to resolving the dilemma. This group is devoting considerable human and financial resources to determine the true scope of the problem, the exact cause, and the most effective treatment of vaccine-associated sarcomas.

If vaccines are causing problems, why use them at all?

Disturbing as this issue may be, there is great concern that cat owners, attempting to keep their cats from harm, may forego vaccination entirely. The result? Though well-intentioned, these owners may be placing cats at far greater risk of acquiring a fatal infection than any risk the vaccine poses. And in the case of rabies, human health is at risk as well.

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What should I look for?

It is quite common for a small, firm, painless swelling to form under the skin at the site where a vaccine was injected. The swelling is almost always of no consequence, and it usually disappears after several weeks. Rarely, however, the swelling may progress to a sarcoma, so it's important that you contact your veterinarian if you notice a swelling at the vaccine site. In fact, it's wise to contact your veterinarian if you suspect an adverse reaction of any kind after vaccination.

How should I respond?

Until this problem is solved, the best response is to discuss the issue with your veterinarian. In the vast majority of situations, vaccines are much more beneficial than harmful. They continue to do an excellent job of protecting cats from serious infection and disease. But one way to reduce the chance of tumor development is to not vaccinate unnecessarily. Veterinarians are being urged to evaluate each individual cat's risk of infection to guide in deciding which vaccines should be given. After considering both the vaccine and your cat's situation, your veterinarian will assist you in designing a vaccination program that not only protects against infectious disease but is as safe as possible.