Mammary tumors occur in both dogs and cats, and are the most common tumor of female dogs. Risk for mammary tumors is very low for pets that are spayed before their first heat cycle (0.5% occurrence), but increase to 8% occurrence in pets spayed after their first heat cycle, and to 26% after two or more heat cycles.
Clinical signs are regional swelling and/or palpable masses in the mammary gland or chain.
Diagnosis is made via physical examination, but it is not possible to determine if the mass is benign or malignant based on visualization. However, prior to surgical removal full bloodwork and thoracic radiographs are recommended.
Treatment is surgical removal with histopathology to determine if the mass(es) is benign or malignant. Approximately 80-90% of feline mammary masses are malignant, with approximately 50% of canine mammary masses being malignant. Pending results consultation with an oncologist and chemotherapy may be recommended.