Are there any possible adverse effects associated with the leukemia virus vaccine?
Possibly. In the last 10 years, several million doses of leukemia vaccine have been given without any adverse side-effects. However, a form of cancer that will arise at the injection site has been found in a small subset of cats (estimated at between 1 in 10,000 and 1 in 100,000) that have received the leukemia vaccine. This tumor is called a fibrosarcoma, or tumor of the connective tissue. In many cats, it is not possible to remove the tumor with surgery. However, in most cats, the risk of contracting a feline leukemia virus disease and dying of it is considered far greater than development of vaccine-related tumors.
