Canine mammary cancer

Microscopic examination showed that mammary cancer in the dog, especially the more infiltrating types, had often been removed (±50%) in an incomplete way. Local recurrence, detected clinically or at post mortem examination, is frequent.
Metastasis is the most frequent cause of death. Dyspnoea is often, but not always, associated with pulmonary metastasis. Lymphogenous and haematogenous metastasis are common.
By-passing of regional lymph nodes and lungs is extremely uncommon. Pleural metastasis was only found in combination with pulmonary metastasis.
Tumours in the posterior glands had more frequently spread to the lungs and liver than those in the anterior glands. Haematogenous spread to other mammary glands was not detected. Multiple malignant mammary tumours were found to be rare (4%).
Mammary cancer should be treated both surgically and systemically.