Abstract
A 10-year-old male toy poodle dog with an appearance of feminization was presented to the hospital due to two mass lesions in the right third mammary gland and the right inguinal region. They were histopathologically diagnosed as mammary carcinoma and Sertoli cell tumor, respectively. It is suggested that the presence of Sertori cell tumor, resulting hormonal derangement, may contribute to the development of the mammary carcinoma in this case.
