Clinical outcome of dogs with grade-II mast cell tumors treated with surgery alone: 55 cases (1996-1999)

Objective-To determine outcome for dogs with grade-it mast cell tumors trea ted with surgery alone. Design-Retrospective study. Animals-55 dogs. Procedures-Medical records were examined, and signalment; location and size of tumor; staging status; dates of local recurrence, metastasis, death, or last follow-up examination; status of surgical margins; previous surgery, postoperative complications; and cause of death were recorded. Follow-up in formation was obtained via reexamination or telephone conversations with ow ners or referring veterinarians. Univariate analysis was performed to ident ify prognostic factors. Results-60 tumors in 55 dogs were included. Median follow-up time was 540 d ays. Three (5%) mast cell tumors recurred locally, median time to local rec urrence was 62 days, Six (11%) dogs developed another mast cell tumor at a different cutaneous location; median time to a different location was 240 d ays. Three (5%) dogs developed metastases; median time to metastasis was 15 8 days. Fourteen dogs died; 3 deaths were related to mast cell tumor, and 7 were unrelated. The relationship with mast cell tumor was not known for 4. Median survival times were 151, 841, and 827 days, respectively, for these 3 groups. Forty-six (84%) dogs were free of mast cell tumors during the st udy period. A reliable prognostic factor could not be identified. Conclusions and Clinical Relevance-Results suggest that additional local tr eatment may not be required after complete excision of grade-it mast cell t umors and that most dogs do not require systemic treatment.