College of Veterinary Medicine

Cancer in Animals

An Overview of Cancer   



Cancer is caused by uncontrolled and purposeless growth of cells in the body. Other terms for cancer are malignancy, tumor and neoplasia. Cancer can arise from any tissue in the body so there are many types of cancer.

Some forms of cancer have the ability to spread to other sites in the body which are often far from the original site. This happens when cancer cells enter the blood or lymph vessels and are then carried to other organs. Cancers with this type of behavior are considered malignant. Often, it is the spread of a cancer that causes the greatest problems. When a cancer has spread in this fashion, it is said to have metastasized. Some cancers lack the ability to metastasize, but may cause significant damage due to growth and invasion into local tissues. Tumors that do not metastasize and are not invasive are considered benign. Tumor is a general term for cancer whether it is benign (“good cancer”) or malignant (“bad cancer”). Oncology is the branch of medicine dedicated to the study of cancer, and the people treating your pet at WSU are Oncologists and Oncology nurses.


Tumor Evaluation (Work-up): Tumor Staging

The first task for the veterinarian is to determine the extent of the tumor which is a process called tumor staging. Staging information is vital for several reasons including:

1. determination of your pet’s prognosis (i.e., the expected outcome for your pet from the illness) and,
2. formulation of a plan for treatment.

To gather information that can help to determine the extent of the cancer, your veterinarian will need to evaluate your pet by several methods. These usually include blood tests (e.g., blood count, chemistry profile), urinalysis, radiographs (x-rays), tissue aspirate (a sample taken with a fine needle) and biopsy. Tests which your veterinarian may have performed might be repeated at WSU due to the changing nature of your pet’s illness. In addition, as indicated for specific patients, other testing procedures may include: ultrasound, specialized radiologic studies (e.g., CT scan, dye contrast studies), bone marrow aspirate, lymph node aspirate, endoscopy (direct examination of the stomach, colon or bronchi with a specialized scope), and immunologic studies. It is important to note that medicine is not an exact science and despite these staging procedures, it is still possible to fail to recognize small sites of tumor or the presence of tumor in organs that are difficult to study.

Once the tumor staging has been completed, your veterinarian will better be able to discuss treatment options for your pet. The goal of such therapy will also be discussed. Tumors that have metastasized extensively are usually not curable. Therefore, the objective of therapy for these animals is palliation (i.e., afford relief of signs without providing cure, and possibly, prolong life). Localized tumors that are not deeply invasive have the best chance to be cured.

Cancer Therapy

There are several types of therapy used to treat cancer in dogs and cats at WSU. These include surgery, chemotherapy, radiation therapy, and immunotherapy. For some tumors, treatment will consist of a single type of therapy, while combination therapy may be recommended for other types of cancer or for animals with a more advanced stage of disease. On occasion, due to the rarity of a particular tumor, a precise treatment recommendation may not be known. In an effort to test newer (and hopefully more effective) forms of therapy, you may be asked to enroll your pet in an investigative clinical trial. The purpose of such a trial is to learn more about the specific type of treatment (that may be of value to humans and other pets with cancer) as well as hopefully providing a benefit to your pet. Only pet owners of animals with tumors for which there is no effective treatment, or tumors that have not responded to conventional treatment will be offered investigative therapy for their pets.

Should You Treat Your Pet?

Treating animals with cancer is not appropriate for every pet owner. It takes a strong commitment on the part of the owner. Therapy requires frequent trips to the veterinary hospital and can be expensive. For some forms of cancer treatment, once begun treatment is never stopped during the animal’s life although the frequency of these treatments can be decreased. Your veterinarian cannot do it alone since treating pets with cancer is truly a team effort and the pet owner is on the team. It is important for you to present your pet for treatment precisely when requested to do so by your veterinarian since the timing of cancer therapy is critical for obtaining an optimal outcome. In addition, medicines to be given to your pet at home should be administered by you exactly as instructed by your oncologist. Any abnormalities or problems you encounter should be reported to your regular veterinarian or oncologist promptly. Always feel free to ask questions and communicate with us.

Keep in mind your veterinarian is as concerned about the quality of your pet’s life as you are. The goal of the therapy is to keep your pet happy and minimize discomfort. Although some animals may experience transient discomfort from therapy, treatment of most pets with cancer can be accomplished without major distress or detraction from your pet’s enjoyment of life. Just because an animal has been diagnosed with cancer does not mean its life is immediately over. Your commitment to your pet and your veterinarians dedication to providing state-of-the-art care will work together to keep your pet as happy as possible.

Last Edited: Jan 27, 2009 9:19 AM   

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