Mammary Adenocarcinoma in Cats

Mammary adenocarcinoma is a malignant tumour that arises from the glandular tissue of the mammary glands. In cats, these tumours tend to behave more aggressively than similar growths in dogs, and they can spread to other parts of the body, including the lungs and lymph nodes. The tissue involved is the same tissue that produces milk, though these tumours can appear in neutered and intact females, and occasionally in males. Owners often first notice a lump or firm mass along the mammary chain—the paired rows of glands that run along the underside of the chest and abdomen. These lumps may grow quickly or slowly, may be single or multiple, and may feel fixed or mobile beneath the skin. Some cats show no other signs at first, whilst others may develop ulceration of the overlying skin, or changes in appetite, breathing, or energy if the disease has spread. This page explores the signals that may prompt an owner's attention, the biological processes that underlie mammary tumours in cats, the investigations used to characterise them, and the range of approaches that exist for managing this condition. The aim is to orient, not to advise, and to provide a framework for understanding what may be observed.