Mammary cancer in cats is a common health concern, ranking as the third most frequent cancer after lymphoma and skin tumors. Most feline mammary tumors, approximately 80% to 96%, are malignant, meaning they can invade surrounding tissues and spread throughout the body. This aggressive tendency makes early detection and prompt treatment crucial for a favorable outcome.
Identifying Early Signs of Mammary Tumors
Detecting mammary tumors early often involves a careful at-home examination, as cats may not show general signs of illness, such as lethargy or appetite loss, in the initial stages. These tumors typically appear as small, firm lumps or nodules located along the mammary chains on your cat’s underside. Cats generally have four pairs of mammary glands, extending from the armpit area to the groin. Gently running your hands along these areas can help you feel for any unusual swellings or changes.
Other signs of a mammary tumor include ulcerated skin over a lump, nipple discharge, or the affected area feeling warm or painful. Your cat might lick it excessively. If the tumor has progressed, a strong odor might develop due to exposed tissue.
Key Risk Factors and Prevention
Hormonal exposure plays a significant role in mammary cancer development. Unspayed female cats are at a higher risk due to the influence of reproductive hormones like estrogen and progesterone, which can encourage mammary gland cells to become cancerous.
Spaying, particularly at a young age, is the most effective preventive measure. Cats spayed before six months of age reduce their risk by up to 91%. If spaying occurs between seven and twelve months, the risk is still substantially reduced, around 86%. However, this protective effect significantly diminishes after two years of age. Mammary tumors are most commonly seen in middle-aged to older female cats, typically between 10 and 12 years of age. Certain breeds, such as Siamese cats, also have a higher predisposition and may develop tumors younger.
The Veterinary Diagnostic Process
When a lump is found, your veterinarian will begin with a physical examination. This includes palpation of all mammary glands and associated lymph nodes, such as those in the axillary (armpit) and inguinal (groin) regions. Even if lymph nodes appear normal, they may still be sampled.
A fine-needle aspirate (FNA) is often performed to collect a sample of cells from the lump for microscopic examination. While FNA can help rule out other growths, it may not always provide a definitive cancer diagnosis or differentiate between benign and malignant tumors. A tissue biopsy, which involves surgically removing a portion or the entire tumor, is the most reliable method for confirming cancer and determining its specific type and malignancy.
If cancer is confirmed, the veterinarian will recommend “staging” to determine if the disease has spread. This process includes chest X-rays to check for lung metastasis. An abdominal ultrasound may also evaluate internal organs and lymph nodes for signs of spread. Blood work and urinalysis are standard parts of the diagnostic workup to assess the cat’s overall health and ability to tolerate treatment.
Treatment Approaches for Early Stage Cancer
Surgical removal is the primary treatment for early-stage feline mammary cancer. The surgical approach depends on the tumor’s characteristics. A simple lumpectomy, removing only the visible lump, is generally not recommended due to the high likelihood of multiple tumors and cancer spreading along the mammary chain.
Instead, a unilateral mastectomy is often advised. This procedure involves removing the entire mammary chain on the affected side, including all four mammary glands. A more comprehensive approach, a bilateral radical mastectomy, may be performed in two stages, spaced several weeks apart to minimize anesthetic risk. This extensive surgery is performed because feline mammary tumors are frequently malignant and can develop in multiple glands.
Following surgery, chemotherapy may be recommended as adjuvant therapy, particularly if the tumor was large, aggressive, or if there is evidence of spread to lymph nodes. Chemotherapy targets and eliminates any microscopic cancer cells that may have spread throughout the body. Commonly used drugs include doxorubicin or cyclophosphamide, often given in combination. Its benefit in extending overall survival time after surgery remains a topic of ongoing research.
Prognosis and Post-Surgical Recovery
The prognosis for cats with mammary cancer is influenced by tumor size at surgical removal. Early detection, when tumors are small, offers the most favorable outlook. Cats with tumors smaller than two centimeters often have longer survival times, potentially exceeding three years. In contrast, cats with tumors larger than three centimeters generally face a poorer prognosis, with median survival times around six months.
Post-surgical recovery focuses on your cat’s comfort and healing. Pain medication will be prescribed. Incision care, including keeping the surgical site clean and dry, is important. An Elizabethan collar (e-collar) will be necessary to prevent licking or chewing at the stitches. Regular follow-up visits with your veterinarian are important to monitor healing and check for any signs of recurrence or metastasis.