Mammary Carcinoma in Dogs

Mammary (breast) tumors account for almost half of all cancers seen in female dogs. Intact females have a sevenfold increased risk of developing mammary cancer compared to neutered females. The two most common sites of metastasis are the lymph nodes closest to the tumor (regional lymph nodes) and the lungs. Dogs with mammary tumors less than 3 cm in diameter have a much higher likelihood of being cured by treatment than dogs with larger tumors. Dogs with tumors that ulcerate overlying skin have a worse prognosis than dogs with tumors without ulceration. Complete removal of the tumor as assessed by histopathology has been shown to increase the length of survival. Nutritional support, and possibly diet modifications as suggested above under prognostic factors, could be important for dogs with mammary carcinomas. Pain relief after surgery, particularly if the surgery is extensive, is mandatory.