Mammary tumors are the most common tumor in intact female dogs. Early detection and appropriate treatment offer excellent outcomes, while prevention through neutering eliminates risk entirely.
Large, ulcerated, or metastatic mammary tumors cause significant suffering: pain, restricted movement, secondary infections, and systemic illness from metastatic disease. The suffering is compounded by the fact that many tumors are detected late when they have grown to a size causing obvious discomfort — early tumors often go unnoticed without deliberate examination. Preventive neutering of females not intended for breeding eliminates this welfare risk. For intact females, owner education about monthly mammary examination enables detection at a stage when surgical cure is most achievable. The welfare gap between well-monitored and poorly monitored intact female dogs is substantial.