Vaccine Related Sarcomas

Cat getting an injection

What are vaccines and what do they do?
Vaccines are still the best defense cats have against many common and often fatal diseases. When a kitten is born he/she receives what is called passive immunity from the mother. This occurs when kittens first drink their mother's milk. This first milk, also known as colostrum, contains antibodies to many common feline diseases. With the addition of those antibodies to the system the kitten now has a limited immunity. As passive immunity wears off, a common option is to have the kitten receive vaccinations.

A vaccine is a preparation containing a non-pathogenic form of the disease. This may take the form of giving antigen in small amounts of dead or attenuated form of the pathogen. Administration of the vaccine will cause the body to produce antibodies against the disease. If and when the cat encounters the pathogen later in life, as the cat already has antibodies against the disease, the cat stands a very good change of not becoming ill and fighting off the pathogen successfully. This type of immunity is known as adaptive immunity. As adaptive immunity can wear off, most vaccinations require yearly or tri-yearly boosters.

What vaccines do cats typically receive?

FVRCPP or FVRCPC - This is one of the most common vaccines given and is a basic upper respiratory vaccine. It protects against Rhinotracheitis, Calicivirus, Pneumonititis (Chlamydia) and Panleukopenia.

Rabies - Rabies is still a very large threat to felines in the United States. Of all domesticated animals, cats have the highest incidence of rabies. As rabies also affects humans, this vaccine is usually mandated by law in most of the United States.

FeLV - A vaccine exists for FeLV, which is now the leading viral killer in felines. FeLV is highly contagious, fatal and there is no known cure for it.

FIP - FIP is another fatal and incurable viral killer in cats. This vaccine is highly controversial as its efficacy has not totally been proven and many think the vaccine may actually do more harm than good.

What problems are associated with vaccines?
Cats can have a variety of reactions to vaccines. Most cats will have no reaction at all, however, veterinarians are seeing an increasing number of cats exhibiting mild to severe allergic-type reactions and vaccine-related sarcomas (cancers).

Some cats will develop a mild reaction that may last for a few days to a week after the vaccination. Mild reactions can include a variety of symptoms such as mild fever, lethargy, poor appetite, sneezing or respiratory problems, slight discomfort at the injection site, slight swelling at the injection site, and vomiting. Although these symptoms may be mild you should call your vet immediately if your cat has any reaction to a vaccine. Some vaccines have a Chlamydia component to them, and some cats have been found to have reactions to that part of the vaccine. If so, your vet may decide to use a vaccine that does not contain a Chlamydia component in the future.

Some cats will develop a more severe reaction. This type of reaction can range from a severe allergic reaction soon after the vaccination to a tumor that forms at the injection site. Such a tumor will start off as a small swelling or lump at the injection site. However, this lump will not go away after a few weeks but will grow. This type of tumor is known as a vaccine-related sarcoma and is a form of cancer. If your cat has a lump at the injection site that does not go away after a few weeks but persists for a month or more, if the lump is larger than a few centimeters in diameter, or if the lump seems to be increasing in size then your cat may have a sarcoma.

As with any suspected cancer your vet will first send a biopsy of the lump to a lab for tests. If the lump is found to be malignant your vet will want to start treatment as soon as possible. Vaccine-related sarcomas seems to be very fast-acting cancers that can be very resistant to treatment. The best treatment seems to be a lumpectomy, or complete removal of the lump and surrounding tissue, within 12 weeks after the vaccine is given. With vaccine-related sarcomas, a timely diagnosis and treatment is the best defense. At this point in time it is not completely known why cancer seems to be linked to vaccination. Cancer has been seen with many different vaccines (rabies, FeLV, FVRCPP) and in vaccines that are manufactured by different drug companies.

So do I vaccinate or not?
So does this mean that you shouldn't vaccinate your cat? No, but it does mean that you need to be aware of the pros and cons of vaccination. And through weighing both sides of the equation with your veterinarian you need to come to an educated decision. For example, if you have an outdoor cat the chances of that cat getting into a fight and contracting rabies, FeLV, an upper respiratory disease, or a herpesvirus probably is greater than the risks associated with vaccination. However, if you have an indoor cat that lives alone and doesn't come in contact with any other animals, the chance of that cat contracting any of the diseases you would vaccinate for are relatively slim. Thus in that situation one may decide to forgo the risks associated with vaccination and simply not vaccinate the cat. The best way to determine if you should or should not vaccinate is to discuss vaccination with your veterinarian. Based on your individual cat's risk of exposure, current health status and past medical history your vet can recommend what is best for your feline.

What is being done in the veterinary community to deal with this?
In November of 1996 the Vaccine Associated Feline Sarcoma Task Force was formed by the American Veterinary Medical Association. This task force works to better define just how serious this problem is, to research what causes vaccine-related sarcomas, and to educate the public and veterinarians about such sarcomas and how to prevent them. The VAFSTF has also created a set of recommendations to all persons administering vaccines. These recommendations include always giving certain vaccinations in the same spot (for example the FeLV vaccine is supposed to be given in the left rear leg), and documenting all vaccinations as to which vaccine was given, the maker of the vaccine, and where the vaccine was injected. Such information may be useful in better understanding these sarcomas, why they happen, and how to prevent them.

In the meantime the best defense against any type of vaccine reaction is owner education. Remember, vaccine reactions do not occur in a majority of pets, and vaccines are still the best way to protect our pets from certain diseases. Talk to your vet, discuss your pets' options and choose whether or not to vaccinate based on what is best for your pet. Your vet may urge you to still vaccinate for all diseases, to only vaccinate for some, or to not vaccinate at all.

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