Fibrosarcomas in cats may occur secondary to infection with feline sarcoma virus especially when in combination with feline leukemia virus. These viruses mainly effect young cats and can produce multiple fibrosarcomas. Fibrosarcoma virus is spread horizontally (cat to cat).

There is also strong evidence for a link between administration of feline leukemia virus and rabies vaccines and subsequent development of fibrosarcoma at previous vaccination sites. These tumors are very aggressive and tend to be surrounded by an area of granulation tissue (inflammation) with tumor tissue extending well beyond the visible margins of the mass.

Surgical removal is the main treatment however margins of at least 3cm beyond the visible lesion is recommended. Edges of the removed tissue should be check histopathologically (microscopic examination) for evidence of tumor cells. Additional radiation therapy should be considered to help reduce the chance of recurrences