Cutaneous metastasis of mammary gland tumor in a dog: a case report

An 8-year-old spayed female, mixed dog presented multiple, bloody exudative skin lesions on the bilateral flank which spread 1 week after mastectomy for treatment of mammary gland tumor (MGT). Multiple, ill-marginated, irregular, and heterogeneously thickened cutaneous and subcutaneous lesions and enlarged lymph nodes were identified in ultrasound and computed tomography. Histopathological examination confirmed adenocarcinoma with lymphatic invasion presumed to be metastatic MGT. Clinical signs improved after chemotherapy but died after 1 month. This study suggests that cutaneous metastasis be considered for differential diagnosis of cutaneous lesions in dogs with a history of MGT, although skin metastasis from MGT is rare.