Dear Doctor,
I read online that cats can get cancer from vaccinations. Why should I vaccinate my indoor cat and expose her to cancer when she never goes outside to be exposed to rabies and other diseases that vaccines are used to prevent?
In order to understand the risks vs. benefits of vaccinations for cats, it is important to know which vaccinations are considered core vaccines and which vaccinations are considered non-core vaccines.
The American Veterinary Medical Association (AVMA) defines core vaccinations as vaccinations that protect your pet from diseases that are highly infectious, common to your specific region, have public health significance and/or those with the potential to cause significant harm to your pet. They have been proven to be extremely effective and have a low level of risk that justifies their use.
For our feline patients, the “core” vaccinations include:
- Rabies virus
- Feline panleukopenia virus
- Feline herpes virus-1
- Calicivirus
- For kittens, feline leukemia virus
The AVMA defines non-core vaccinations as vaccinations that can be tailored to individual pets to fit their unique needs. Although these vaccines are technically labelled as “non-core,” these vaccinations can protect your cat from potentially fatal diseases and should be given unless there is a significant reason not to.
For our feline patients, the “non-core” vaccinations include:
- Feline leukemia virus (FeLV)
- Feline immunodeficiency virus (FIV)
- Feline infectious peritonitis (FIP)
- Chlamydophila felis
- Bordetella bronchiseptica
- Feline Giardia lamblia
Although the AVMA clearly defines the need for all cats to receive the core vaccinations, it is important to speak to your veterinarian about your individual pet’s need for certain non-core vaccinations. One such risk that has been a major topic for research and discussion is the feline injection site sarcoma (FISS). The cause of this process is not clearly understood, but approximately 1 in every 10,000 to 30,000 cats can develop a malignant tumor at the injection site. It is thought that this tumor develops due to the inflammatory process in the cat’s body that then transforms into cancerous cells. This cancerous mass typically appears at the vaccination site, especially at the site where rabies or feline leukemia virus vaccines have been used, but can also occur after injection of steroids, antibiotics, and microchips.
Understandably, many feline owners feel concerned when it is time for their cat to have its necessary vaccinations. It is important to remember that veterinarians are working diligently to reduce the risk of FISS for your cat. Based on your individual cat’s risk of exposure to certain diseases, your veterinarian can determine which non-core vaccinations are necessary for your feline. Also, if possible, veterinarians often vaccinate feline patients in the lower limbs (or even the tail), which will, in the unlikely event that your cat develops a tumor, allow the most favorable chance of complete removal of the tumor cells, often through amputation of the affected limb. This may seem like a radical approach to treatment, but aggressive treatment is recommended for this type of malignant cancer to prevent it from spreading to other areas of your cat’s body.
Early detection of FISS is a very important factor for treatment of this type of tumor. This can prove to be difficult because FISS can develop anywhere from 2 months to 10 years after an injection has been administered. It is important to monitor the sites where injections were administered. If a lump develops on your cat and persists for 3 weeks and/or becomes larger, it is important to seek veterinary attention as soon as possible.
