Mammary Gland Tumors in Cats
Key takeaways
Mammary gland tumors are masses that result from uncontrolled cell growth in the mammary (breast) tissue.
- Common in older, unspayed cats and are usually malignant
- The primary symptom is a mass in the breast tissue or around the nipple which may be accompanied by discharge or skin ulceration
- The specific type of tumor is determined through a biopsy
- Physical examination, lymph node cytology, and diagnostic imaging are used to evaluate for metastasis and staging
- Radical mastectomy is usually recommended, often followed by chemotherapy
- In advanced cases, palliative care or euthanasia may be recommended
- Recurrence is high with mammary gland tumors and the best form of prevention is spaying the cat before their first heat
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A closer look: Mammary Gland Tumors in Cats
Mammary tumors are fairly common in cats and approximately 90% of feline mammary tumors are malignant.
More generalized symptoms are associated with metastasis and advanced disease.
The most common type of mammary cancer in cats is adenocarcinoma, which is an unregulated growth of glandular tissue cells. Mammary sarcomas are rare.
Mammary tumors usually carry a poor prognosis. Early intervention provides the best opportunity to improve the outcome. Treatments including both aggressive chemotherapy and bilateral radical mastectomies yield the highest survival rate for cats with metastatic mammary tumors.
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Risk factors
Elderly cats (over 11 years) that have not been spayed are at higher risk than those that are spayed. Mammary tumors can happen in male cats but are rare. Siamese cats show a disproportionate incidence of mammary gland tumors compared to other breeds.
Possible causes
The cause of mammary tumors is not fully defined, but exposure to sex hormones in female cats plays a role. Unaltered cats have a much higher probability of developing mammary cancer than spayed cats because ovarian hormones irreversibly increase the likelihood for mammary cancer later in life.
Some breeds show a higher incidence of formation of mammary tumors indicating a possible genetic component.
Main symptoms
The main, early symptoms of mammary tumors include
- Mass in the mammary chain (can be soft, hard, defined, or widespread)
- Ulceration and discharge around the nipple(s)
Testing and diagnosis
After a physical examination, a number of tests are used to verify and determine the severity and progression of the tumor, including
- Tissue biopsy
- Blood work
- Diagnostic imaging (to look for evidence of metastasis)
Steps to Recovery
Treatment depends on the stage of the cancer and if it has metastasized. Options include
- Surgery: usually radical full-chain (the entire strip of mammary tissue) mastectomy. Feline mastectomy may be unilateral or bilateral and may require removal of the associated lymph nodes.
- Chemotherapy/radiation
- Palliative care
- Euthanasia
Prognosis depends on the stage of the cancer and the treatments utilized.
In cases without metastasis, prognosis is fair with aggressive treatment. Recurrence is high and mammary tumors have a high incidence of metastasis, even with successful treatment.
Prognosis in cases of metastatic mammary tumors is very poor. In most instances, the cancer moves to the lungs, lymph nodes, or cardiac system.
Prevention
Spaying before the age of 12 months reduces the risk of developing mammary gland tumors later in life. Spaying prior to six months of age gives the best chances for preventing mammary cancer in cats. Mammary gland tumors are not contagious.
Are Mammary Gland Tumors in Cats common?
Mammary gland tumors are common in cats.
Typical Treatment
- Surgery
- Chemotherapy
- Palliative care
- Euthanasia
