As the life expectancy of cats has increased, the number of cancers diagnosed has also risen. Perhaps cats, like us, are also suffering from the problems, such as pollution or an owner who smokes, associated with modern society.
A tumor -uncontrolled proliferation of cells- may be benign or malignant. A malignant tumor is called cancer. In cats, malignant tumors are six times more common than benign tumors after the age of three. Skin cancer is the most common cancer in the cat population as a whole, followed by mammary tumors, then various cancers of the soft tissues.
The occurrence of glandular tumors and lymphosarcomas is directly related to the feline leukemia infection rate.
Symptoms of cancer vary depending on the organ affected, the rate of growth of the tumor, whether it is localized or has metastasized, and its impact on other parts of the body (for example, a tumor in the endocrine gland).
Nevertheless, there are some general warning signs that warrant a trip to the veterinarian. Cancer produces localized and non-localized effects. Localized effects include a lump or visible or palpable swelling, destruction of the organ, compression of nearby organs or impaired function. Non-localized effects result from excessive or absence of production of a hormone, or production of substances by the tumor itself. Several non-specific signs may indicate cancer and merit further exploration:
These include weight loss, increased thirst or appetite, convulsions, cough, and internal or external bleeding.
If a veterinarian suspects a cancerous tumor, she will typically perform additional tests to confirm her diagnosis or to provide a more precise diagnosis. Some tests for tumors include x-rays, ultrasounds, and other more expensive techniques such as MRI or scanning. Yet another technique involves examining biopsied tissue or effused liquid under a microscope.
In animals, surgery is the primary treatment for cancerous tumors. Chemotherapy is sometimes elected in conjunction with surgery, or as the sole treatment method. Radiation therapy, in conjunction with surgery and/or chemotherapy, and immunotherapy are promising new techniques, but are still in the development stages.
Study of cancer in cats is of interest to comparative pathology. Feline leukemia, caused by infection with the feline leukemia virus, is one of the oldest known diseases for which researchers have been able to demonstrate cause and effect between a viral infection and the development of tumors.
The tumors most commonly associated with feline leukemia are lymphosarcomas. Though FIV (feline immunodeficiency virus) is not recognized as an oncogenic (causing tumor formation) disease, cats infected with FIV have a higher incidence of certain cancers, such as lymphosarcomas, myeloid tumors, and sarcomas.