Feline injection site sarcoma: current paradigms and future directions

Feline injection site sarcoma (FISS) is an uncommon but important tumour in cats due to its locally aggressive biologic behaviour, poor prognosis and link to routinely-administered vaccinations, which raises ethical questions regarding vaccine practices. Post-vaccinal granulomas commonly occur in cats, therefore client education is vital and careful monitoring should be adopted. Incisional biopsy is recommended to confirm diagnosis of FISS, and full staging is recommended prior to determination of a treatment strategy. Tumour palpation has been shown to vastly underestimate the extent of tumour infiltration, therefore prospective treatment planning with advanced imaging is highly recommended. Although further studies are required to determine the most effective combination of treatment modalities for definitive treatment, a multi-modal approach is often required, based on expeditious and aggressive surgery in combination with radiotherapy ×/− chemotherapy. Importantly, early detection by careful post-vaccination monitoring as well as a shift in vaccination practices is key to improving the outcome of FISS.