Cancer
Cancer (also called neoplasia) is the uncontrolled growth of cells that occurs independently of the body's need for those cells. The cells are often not differentiated, i.e., they have not developed fully. Any cell type in the body may undergo this erratic development and become a cancer. Cancer is typically classified as either malignant (growing worse, life threatening, able to move from one part of the body to another) or benign (mild, not life threatening, usually inconsequential).
Cancers can develop as bumps on the skin, growths in internal organs, diffusely spread throughout different body tissues, growths from bones, or spread throughout the animal’s blood system. Cancer usually develops in older animals but can occur in any animal at any age. General signs associated with cancer include weight loss, loss of appetite, vomiting, bumps or swellings, diarrhea, panting, discomfort, etc. It must be kept in mind that these signs are very vague and can be associated with a wide range of diseases.
A definitive diagnosis of cancer necessitates a biopsy or a fine needle aspirate of a mass or organ. What type of cancer is found will guide treatment and determine prognosis. Further workup is needed to stage the cancer (in other words, has the cancer spread and is it causing adverse systemic effects). Further workup includes a CBC (this checks for anemia, monitors the white blood cell count, and checks platelets), and a chemistry profile (to asses involvement of concurrent disease states of organ systems and to ensure the cancer is not causing harmful metabolic effects). Chest x-rays and/or an abdominal ultrasound may be done to check for metastasis (spread) of the cancer. These tests may be done prior to surgery to remove the cancer.
Treatment for cancer can include surgery, radiation therapy, chemotherapy, or any combination of these modalities. Often patients need to be referred to a specialty clinic to have these treatments done. Not all cancers are susceptible to the same treatment. For instance, lymphoma is a cancer that has been fairly successfully treated with chemotherapy but there are no surgical options, while fibrosarcomas are not responsive to chemotherapy but can be cured surgically. Osteosarcomas generally require both surgery and chemotherapy to be treated. Some cancers, once they have spread, are not susceptible to treatment; this is why an animal with cancer needs to be staged. Staging gives an idea of prognosis and helps determine if treatment is even in the animal's best interest (from both a humane and financial standpoint). Most cancer patients also need a high-energy diet and need to be treated for pain.
The word chemotherapy conjures worries of severe side effects and illness. This results from an individual’s personal experience (with themselves or loved ones) or from what they have heard from friends, family, or the media. It is worth noting that the objectives for chemotherapy in animal patients are different than in people. Due to the lack of life support systems and the cost of these systems in animals without the benefit of health insurance, chemotherapy in animals is not geared at wiping out the cancer but rather minimizing the effects of the cancer. To try and cure the cancer completely would likely kill the patient, so a lower, less intense dose of chemotherapy is given. Furthermore, since animals' lifespan are inherently shorter than humans, there is less benefit in achieving a complete cure and putting the animal through intensive treatment when their expected lifespan is typically only a few more years even without the cancer. It is still possible for animals to have adverse reactions to chemotherapy and screening tests are done before administering the drugs to minimize these reactions. The screening tests done depend on the drug to be used.