Evaluation of the submitted ovarian mass confirms the diagnosis of papillary carcinoma based on the cell morphology and the presence of arboriform papillae. The prognosis for dogs with ovarian tumor is difficult to evaluate due to the lack of enough information in the literature. Generally, the prognosis is good with complete excision of benign or localized malignant tumors but poor with metastatic disease. Metastasis usually occurs transcoelomically after rupture of the tumor or invasion of the neoplastic cells through the capsule leading to peritoneal implantation. Often subsequent ascites and abdominal distention from lymphatic blockage can occur. Metastasis also can occur after lymphatic or venous invasion. Although the current lesion has been completely removed, the possibility of transcoelomic transmission should be of concern (the transcoelomically implanted neoplasm may not be detected during the time of surgery). Therefore, regular follow-up for ascites or peritoneal mass is recommended.