A 6 year old male castrated Labradoodle presented to the Cornell University Hospital for Animals Soft Tissue Surgery service with a six month history of a subcutaneous mass on the left antebrachium, previously diagnosed as a grade II mast cell tumor. Staging was performed by the Oncology service, and no evidence of metastasis was found. A computed tomography was performed to determine the extent of local invasion of the tumor, and to assist with the planning of surgical margins. The mass was excised with margins of 3 centimeters laterally and one fascial plane deep. Negative pressure wound therapy was initiated on the open surgical wound for one week, until histopathology confirmed complete excision of the tumor. A full-thickness skin graft was performed on the open wound, and negative pressure wound therapy was continued to assist in graft incorporation. Pinch grafts were added to the areas that did not incorporate, and these healed successfully.