Feline Injection-Site Sarcoma

4 April 2018 – News

Feline injection-site sarcomas (FISS) are malignant tumors that arise at the site of an injection in cats. Only a small number of cats develop this adverse reaction, which may indicate that genetic factors are also involved in the appearance of these abnormal growths.

In most cases, these tumors are fibrosarcomas. Although this has not been fully proven, it is generally accepted that they start growing after a chronic inflammatory reaction at the inoculation site stimulates fibroblasts and leads to the appearance of malignant cells. This can happen after the administration of a vaccine, a long-lasting drug or any other irritating substance.

Although FISSs are not very common, they are highly invasive with metastasis typically spreading to the lungs, regional lymph nodes and abdominal organs. The treatment approach should involve staging and aggressive surgical tumor resection with wide margins to avoid recurrence. Adding other therapies such as radiotherapy or immunotherapy improves the affected animal’s prognosis.

Vaccination plans should be tailored to each individual, as it’s important to avoid over-vaccination. Non-adjuvant vaccines, modified live vaccines, and vaccines with a long duration of immunity should be chosen over inactivated vaccines with adjuvants. Vaccinations should be given at room temperature and close monitoring of the injection site following the administration should be recommended to the owners.

In Hartmann, Katrin & J Day, Michael & Thiry, Etienne & Lloret, Albert & Frymus, Tadeusz & Addie, Diane & Boucraut, Corine & Egberink, H.F. & Gruffydd-Jones, Timothy & C Horzinek, Marian & Hosie, Margaret & Lutz, Hans & Marsilio, Fulvio & Pennisi, Maria Grazia & D Radford, Alan & Truyen, Uwe & Möstl, Karin. (2015). Feline injection-site sarcoma: ABCD guidelines on prevention and management. Journal of feline medicine and surgery. 17. 606-13. 10.1177/1098612X15588451.