First of all, there are hundreds of different kinds of cancer. Cancer is a disorder of cell growth. The abnormal growth of these cells usually results in a mass of tissue, or tumor. However, not all tumors or growths are considered to be cancer. Cancer is also known as malignant neoplasia. Other non-neoplastic tumors are referred to as benign. Oncology is the study of neoplasia.
The causes of cancer in pets are very similar to the causes of cancer in people. Genetics play a major role in the susceptibility of certain pets to cancer. Some breeds definitely have a greater tendency to develop cancer.
Just like people, most cancer patients are older pets, but on occasion a young pet may have cancer. Also, environmental factors that cause cancer, called carcinogens, may be involved. Such factors include sunlight, chemicals, secondhand smoke and some infections. There are even some cases where viruses can cause cancer to develop. Cancer is extremely unpredictable.
Some types of cancer may begin in one location of the body, known as the primary cancer, and then spread rapidly to other parts of the body causing secondary cancer. Other types may spread either moderately or even very slow.
Some types of cancer do not tend to spread to other body parts but are known as locally aggressive. These types can be just as life threatening and often reoccur very fast after being surgically removed. I have seen a locally aggressive cancerous tumor return and be twice as big as originally within two weeks of being surgically removed. Others may be surgically removed and never return resulting in a complete cure.
For the most part, cancer is not contagious from pet to pet, except in the cases where a virus that is capable of causing cancer is spread from one to another. For example, Feline Leukemia virus can cause cancer of the blood and lymph systems in cats. The virus may be transmitted from cat to cat and even from a pregnant cat to her unborn kittens.
The most common and most obvious symptom of cancer is when an actual tumor develops. However, other symptoms of cancer can be weight loss, anorexia, lethargy, vomiting and diarrhea, especially internal cancer that is not outwardly obvious. There are numerous diagnostic tests useful in determining if your pet may have cancer. Depending on the symptoms present and the area of the body affected, certain diagnostic tests are more specific for the type of cancer suspected. With internal cancer, blood tests as well as X-rays may be necessary to diagnose or rule out cancer. Specific blood tests for the viruses that cause cancer in cats can be performed, usually within minutes in the office.
If there is an actual tumor present, there are a couple of ways to test it for cancer. First, your veterinarian could perform a fine needle aspirate. This test involves inserting a needle into the tumor while trying to aspirate some material that would be placed on a microscope slide and sent out to a lab. A pathologist would examine the slide by looking under a microscope at the different kinds of cells in the material. If there are cancer cells present then a definitive diagnosis can be made.
However, sometimes the pathologist may report that there was not enough material aspirated to make a diagnosis. In this case, a full biopsy is recommended. A biopsy is when your veterinarian performs surgery to cut out a piece of the tumor and then sent it to a pathologist for examination. Often times, it is more beneficial to surgically remove the entire tumor and send it to the lab so that a second surgery can be avoided if the biopsy came back as cancer.
If I suspect that a growth might be cancer, I recommend having surgery to remove the entire tumor with the hopes of getting all of the cancer cells and then the tumor can still be tested. The report may come back as non-cancerous, but I think it is better to error on the side of caution.
Fortunately, there are treatment options for most types of cancer. The most common and effective treatment is surgical removal of a tumor. Even if the type of cancer is not surgically curable, chemotherapy or radiation may be performed after surgery or instead of surgery. A lot of people do not realize that chemotherapy and radiation are available for pets. Certain types of cancer respond very well to these treatment options.
Early detection is the key to successful treatment of most cancers in pets. Therefore, if your pet shows any signs of cancer, contact your veterinarian as soon as possible to ensure your pet lives a very long, healthy and happy life.