A vaccine-associated sarcoma (VAS) is a type of malignant tumor found in cats and rarely, dogs that has been linked to certain vaccines.
Typically the sarcoma appears within a few weeks of vaccination, in the form of a rapidly growing lump which may ulcerate through the skin. Vaccine-related sarcoma is infamous for being extremely fast-growing and aggressive, and it requires prompt action. The vaccine most closely associated with vaccine-related sarcoma is the rabies vaccine.
Often, the cancer spreads to the lungs, but it may spread to the regional lymph nodes and to the skin as well.
Lesions occur at the site of the vaccination, persisting and/or growing in size. In the advanced stages, the lesions will become fixed and occasionally ulcerated.
