What are vaccine-associated fibrosarcomas?
A fibrosarcoma is a tumor of the connective tissue. These tumors tend to invade deeply into the underlying tissues. The frequency of these tumors is increasing in cats and has led researchers to believe some of the tumors may be caused by a local reaction to a vaccine. Although these tumors are seen more frequently, they are still rare. Current estimates on the incidence of these tumors are about one tumor per 10,000 to 30,000 cats vaccinated. These tumors are most commonly associated with the FeLV vaccine.
