For some cancerous tumors, they can have microscopic extensions of their cells into the surrounding tissue that cannot be seen or felt (like tentacles growing from the tumor). For this reason, we often recommend removing the tumor along with some of the surrounding normal tissue to try to get all of these microscopic tumor cells to prevent the regrowth or spread of the tumor. 

For non-cancerous tumors, obtaining this margin of normal-appearing tissue is often not necessary. 

Depending on the type of mass, its’ size and location, your veterinarian may recommend some additional testing prior to surgery like chest x-rays, abdominal ultrasound, or a CT scan. These tests can help us determine if there is any evidence of spread of cancer to other organs, and ultimately help us make the best surgical plan for your pet.