Understanding vaccine-associated sarcoma in cats, an aggressive tumour linked to certain injections, and how veterinary practice is evolving to reduce risk.
Feline injection-site sarcoma creates a genuine welfare dilemma: the risk is real but rare, and the alternative — not vaccinating — carries higher overall risk from preventable infectious diseases. The welfare burden of FISS on affected cats is severe: aggressive surgery, potential limb amputation, radiation therapy, and high recurrence rates mean many affected cats experience significant suffering before euthanasia becomes necessary. Veterinary practice has evolved in response, including site rotation, use of non-adjuvanted vaccines, administering injections in easily amputated sites (distal limbs), and monitoring injection sites for persistent lumps. Owner education about the signs of FISS — any lump persisting more than 4 weeks at an injection site — enables early detection when treatment outcomes are marginally better.