Vaccine-associated fibrosarcoma is a rare but serious complication of feline vaccination with significant welfare implications for affected cats.
Injection site sarcoma represents a tragic welfare dilemma - vaccines protect cats from fatal infectious disease but carry a small risk of aggressive cancer at injection sites. The welfare response is to minimize risk while maintaining protection: using nonadjuvanted vaccines where available, injecting at sites amenable to complete excision, and monitoring closely for early tumor development. When tumors develop, aggressive early surgical excision offers the best chance of prolonged survival. Delayed or incomplete excision - often driven by owner reluctance or cost - leads to rapid recurrence and reduced survival.