Suspected eccrine adenocarcinoma on footpad of the right hindlimb in a dog

A 12-year-old, male miniature dachshund has an ulcer on the footpad of the right hind limb. Despite treatment for longer than 6 months, the ulcer did not heal. Biopsy of the lesion was done to make a definitive diagnosis. Histologically, there were lumens containing weakly eosinophilic fluid surrounded by tumor cells with a similar circular pale nucleus and distinct nucleoli that showed some variation in size. Immunohistochemically, the tumor cells were positive for cytokeratin (AE1/AE3) and vimentin, were negative for S100 and p63. A poorly differentiated eccrine adenocarcinoma was diagnosed. Treatment was started with toceranib, an anti-angiogenic agent, and enlargement of the lesion was not observed during the administration period.