Mammary Tumors in Cats
General Information
Mammary tumors are very common in cats. About 80% are cancerous. Siamese cats tend to have more cancerous mammary tumors than other cats.
Mammary tumors are more frequent in cats over 9 years of age, but they have appeared in cats as young as 9 months. Spayed cats are less likely to develop mammary tumors. Though the cause of these tumors is unknown, researchers suspect a hormonal influence.
Early and complete surgical removal of the mammary glands and associated lymphatics offers the best chance for complete recovery. The larger the tumor at the time of removal, the greater are the chances of recurrence or spread.
Understanding Your Pet's Medical Diagnosis
What are mammary gland tumors in cats?
Mammary gland tumors in cats are tumors that affect one or multiple mammary glands. They may be benign or cancerous (malignant). Benign tumors do not extend into other tissues (that is, they are relatively non-invasive) and they do not spread into other parts of the body (that is, they do not metastasize). Unfortunately, almost all mammary gland tumors in the cat are cancerous. These malignant tumors do extend into other tissues (that is, they are highly invasive) and they do spread into other parts of the body (that is, they do metastasize). Mammary gland tumors are primarily a disease of older, intact female cats; however, the Siamese have a higher risk of developing these tumors at a younger age.
What causes mammary gland tumors in cats?
The actual cause of mammary gland tumors in cats is not known; however, it is thought that tumor development may be associated with hormonal changes. The risk of mammary gland tumors is seven times higher in intact female cats than the risk in spayed female cats.
What are the signs of mammary gland tumors in cats?
At time of physical examination, many cats already are in the advanced stages of this disease. The common clinical signs associated with mammary gland tumors in cats include single or multiple masses in the mammary area that may be ulcerated. Some cats may have swollen hind limbs, as the tumors physically impair blood circulation to the hind limbs.
How are mammary gland tumors diagnosed in cats?
Mammary gland tumors are diagnosed in cats upon physical examination. However, as most tumors are cancerous, chest radiographs (X-rays) should be performed to determine if spread to the lungs (metastasis) has occurred already. Unfortunately, some tumors may have spread to the lungs but not yet be large enough to be detected on X-rays. The tumor generally is aggressive; therefore, a preliminary biopsy (small tissue sample) is not recommended. The mammary tissues obtained at the time of mastectomy (surgical removal of the affected mammary glands) can be analyzed to confirm the diagnosis.
How are mammary gland tumors treated in cats?
Surgical removal of the mammary glands by radical mastectomy may be performed in all cases where the tumor cells apparently have not yet spread (metastasized). A radical mastectomy involves the removal of all four mammary glands on the affected side, along with the associated lymph nodes. Chemotherapy is an option in those cats with spread of the tumor to other body sites (metastasis) or extensive tumor growth. However, due to the toxic side effects associated with chemotherapy, regularly scheduled re-check examinations will be required to monitor the response to treatment and to evaluate the overall health of the animal.
What is the prognosis for cats with mammary gland tumors?
Due to the aggressive nature of this disease and the high incidence
of recurrence and spread (metastasis), the prognosis (outcome)
for cats with mammary gland tumors is poor. The single most important
prognostic factor is the size of the tumor; surgical removal of
small tumors is associated with longer survival times than seen
following surgical removal of larger tumors
Important Points in Treatment
1. Surgical removal of the tumor is the treatment of choice. Age and general health of the patient govern the decision regarding which treatment is best for your pet.
2. Radiographs (x-rays) may be necessary to determine whether the tumor has spread to other parts of the body.
3. A biopsy (tissue sample) may be submitted to a pathologist to determine whether the tumor is cancerous.
4. Laboratory tests may be required to determine whether your cat requires supportive therapy before or during surgery.
Recommendations:
The information on this page was obtained from the site www.vetmedcenter.com