• Feline injections site sarcoma is a highly aggressive variant of sarcoma that arises at sites of chronic inflammation, most often secondary to vaccination sites. • Cytology is often not diagnostic in cases of FISS and incisional biopsy is recommended. • This disease is extremely locally aggressive and 3cm margins are typically not adequate for treatment. • 5cm margins and 2 fascial planes are recommended for surgical treatment alone. • Radiation can be combined with surgery in cases where 5cm margins are not feasible or desired. • The primary care veterinarian is the most important part of this equation. With judicious vaccination protocols, the use of non-adjuvanted vaccine and placement of vaccines of the distal extremities, there is a much higher chance of a successful outcome.