This study described the pathological aspects of a metastatic grade II simple tubulopapillary mammary carcinoma in a free-living senile female maned wolf (Chrysocyon brachyurus). The diagnosis was based on histopathological findings of malignant epithelial cells arranged in tubular and papillary patterns, with marked anisocytosis and anisokaryosis and metastases to regional lymph nodes, lungs, parietal pleura, and pericardium. Also associated to positive immunolabeling of neoplastic cells for Cytokeratin AE1/AE3 and negative for P63, Calponin and Cox-2, added to the cell proliferation index of 26.8%. The findings demonstrated that free-ranging wild canids develop mammary neoplasms similar to those observed in domestic canids.