A case of Transmissible Venereal Tumor (TVT) with mammary gland metastase of a nine years old Collie bitch is described in this paper. The dog was presented with vaginal discharge containing blood and with a mass in the mammary gland. Tumoral masses were detected at clinical examination in vestibulum vagina and in the right back inguinal mammary gland. After masroscopical and microscopical examination, the diagnosis of TVT was performed. Knowledge about the history, clinical, laboratory and pathological findings, and the treatment ol the case were given.