grovercentervetAny pet owner’s nightmare has to be finding a lump on their pet’s body and that is especially true for the female cat. Cats with mammary tumors are one of the most important and commonly diagnosed reproductive cancers in animals, as mammary cancer comprises about 17% of all tumors in female cats.
Canine “mammary growths” have a 50/50 chance of being avulse, but that’s not the case with feline mammary growths. Nearly 85-95% of mammary tumours in cats are very aggressive, locally invading and are a high risk to spread to nearby lymph nodes and other organs such as the lungs. As this cancer is so quick to develop, it is paramount that the owner knows the risk factor, recognises signs of the disease early and gets their cat into a rapid veterinary treatment protocol—a treatment plan that will help to prolong their life.
So, What causes Mammary Tumors in cats?
Hormonal influences are a major contributing factor to why mammary tumors occur in cats and this is because they are exposed to estrogen and progesterone on a regular basis during normal heat cycles. Ovariohysterectomy (spay surgery) is the single best preventative measure against mammary tumors occurring in cats.
Spayed before 6 months of age: decreases lifetime risk of mammary cancer by a huge 91%.
Spayed at 7-12 months of age: decreases risk by about 86%.
Spayed between 13 and 24 months old: Reduces risk by 11%.
Spayed after 2 years of age: No benefit in terms of protection from mammary tumors for cats.
Further Hormonal Risk Factors
The use of exogenous progestins (synthetic hormones that may be prescribed by a veterinarian for certain skin problems and/or behavioral disorders) significantly increases the risk. Cats treated in this way run more than 3 times the risk of developing malignant mammary tumors in cats.
Age and Breed Predispositions:
ost of the cats affected are older (11-13 years median) intact females. Any domestic cat can be affected but, in Siamese cats, the tendency is quite strong, and they often get these tumors at a much younger age than other breeds.
2. Recognizing the Signs and Symptoms
Cats have four pairs of mammary glands from the top of the chest through to the groin area and mammary tumors can develop anywhere along these lines. When diagnosed, from 60% of felines affected will have more than one distinct mass on both chains.
Owners should regularly palpate the abdomen at home and carefully look for these clinical signs:
Firm, Nodular Lumps: Small, pea-sized pebbles or firm, irregular thickening under the skin, next to or under a nipple.
Skin Ulceration and Discoloration: When a malignant growth or tumor grows, the skin is stretched until it tears apart, leaving a sore that is raw, weeping, or bleeding and giving off an unpleasant odor because of secondary bacterial infection.
Localized Swelling and Pain: The affected mammary glands may be abnormally warm, red or swollen and the cat will be visibly uncomfortable when picked up.
Systemic Illness or Breathing Distress: If mammary tumors in cats have been successful in metastasizing to the thoracic cavity, the cat may become lethargic, lose weight, have an uncharacteristic loss of appetite, or begin to breathe quickly and shallowly.
3. Important Clinical Diagnosis and Staging
When a veterinarian sees mammary tumors in a cat, she will perform a thorough staging panel to determine the extent of the disease before any surgery is done.
Biopsy and Histopathology
Fine-needle aspiration (FNA) may be useful to exclude skin cysts, but a biopsy or removal of the tumor and complete histopathology will be the best method to diagnose mammary tumors in cats. Pathologists analyse the cells to determine the type of carcinoma (e.g. tubular, ductal or anaplastic) and give a histological grade (Grade I, II or III), depending on how aggressively the cells are dividing.
Advanced Imaging
A 3-view thoracic X-ray panel is a must for a cat with mammary tumors as these can easily spread into the chest cavity and lungs. If you notice any signs of cancer spreading to the lungs (pulmonary nodules), the treatment plan changes from aggressive surgery to aggressively palliative care. An abdominal ultrasound is also commonly ordered to see if there is any spread within the abdomen to the liver, spleen or medial iliac lymph nodes.
4. Treatment Approaches and Prognosis
Treatment approaches and prognosis are significantly related to one basic number when it comes to mammary tumors in cats: the size of the primary tumor at the time of surgery.
Tumor Size and Prognosis
Tumor Size Group
Clinical Characteristics
Expected Median Survival Time
Small Tumors (< 2 cm)
Early detection, localized to the primary gland
3+ years (with radical surgery)
Medium Tumors (2 to 3 cm)
Intermediate stage, potential lymph node involvement
1 to 2 years
Large Tumors (> 3 cm)
Advanced local disease, high likelihood of cellular tracking
4 to 6 months
The Standard of Care: Radical Chain Mastectomy
Because all the mammary glands on one side of a cat’s body are connected by shared blood vessels and lymphatic channels, conservative “lumpectomies” are highly discouraged in treating mammary tumors in cats. Surgical treatment is the gold standard, and involves either a unilateral or bilateral radical mastectomy where the whole line of mammary tissue and any regional lymph nodes are removed on the affected side to reduce the risk of aggressive local recurrence.
When surgery is a success, an oncologist might suggest that the pet receive the same drug treatments as systemic chemotherapy, most commonly by injection with the drug carboplatin or doxorubicin. In cats with high-risk factors such as vascular invasion or high grade tumor, chemotherapy can help to postpone the progression of metastatic disease, giving cats important extra months or years.
5. Medical Management and Palliative Care
Medical management of the cat with an advanced, non-resectable mammary tumor and when the cancer has already spread to the lungs is chronic palliative management, where the aim is to maintain the maximum possible comfort, pain reduction and preservation of the quality of life of the cat.
1. Offer personalized pain management:
Use veterinary prescribed non-steroidal anti-inflammatory drugs (NSAIDs) and/or some pain modulators for the nervous system that have been developed for pets on a regular basis to ensure maximum comfort.
2. Continue Strict Wound & Hygiene Management:
If the tumour has broken through the skin surface, keep the area clean, wear loose protective shirts as recommended by your vet and do not let the cat over-groom or lick the raw skin.
3. Prescribe Targeted Antibiotic Therapies:
Make use of wide spectrum antibiotics to actively treat secondary bacterial infections in weeping, open mammary sores to help reduce inflammation and odors.
4. Report on QoLM regularly:
Assess daily activities of your cat within a structured QOL framework, to make sure that good days outweigh bad days for your cat as far as their appetite, hydration and general comfort are concerned.
Frequently Asked Questions (FAQs)
Q1. What is the survival rate for a cat diagnosed with mammary tumors?
Tumor size at diagnosis is the almost sole determinant of survival. For cats less than 2 cm in size, a radical mastectomy may result in a few years of survival. If the tumour is bigger than 3 cm or the tumour has spread to the lungs, the median survival time decreases to less than 6 months.
Q2. Do male cats get mammary tumors?
Yes, but it’s unusual. Cats are less likely to develop mammary tumors if they are male, accounting for less than 1% to 5% of all mammary tumor cases. In male cats, however, once it develops, mammary cancer is as aggressive as it is for female cats and is staged and treated identically.
Q3. Is a lump in a cat's mammary gland always cancer?
Some mammary tumors in cats are very malignant cancers, but it is a small possibility that the mass is a benign adenoma or feline mammary hypertrophy, which is a benign fast-growing growth caused by a hormone, progesterone. They can only be distinguished safely by a professional biopsy.
Q4. What are the causes of death of mammary tumors in cats?
With progression of malignant mammary tumors in cats there are two ways in which complications can occur. The first is that it can cause the main external tumours to open up, become infected, bleed and cause massive systemic inflammation. Second, the cancer spreads to the lungs and, over time, becomes unmanageable and causes the cat to become uncomfortable breathing.
