CANINE CANCER

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The wait is over on the diagnostic tests, and yes it confirms our worst fear for our dog: definitive diagnosis is CANCER. These tests will also tell us what type and grade of cancer our pet has. There are many types of cancer, but according to Veterinary Oncologists, some of the most common types are:

See Part I

In the second part of our three part series on dogs and cancer, Shantel McCook discusses the different types of cancer and treatment options:

Types of Cancer

Lymphoma represents 20 percent of all canine cancers, encompassing four main types. Currently, dogs are 2-5 times more likely than people to develop lymphoma. This tumor can affect any breed of dog at any age. Some breeds, such as the Golden Retriever, are more likely to be affected, indicating a likely genetic component to the development of lymphoma.

Hemangiosarcoma is a tumor that develops from cells that line blood vessels (endothelial cells). This tumor most commonly affects middle-aged or older dogs of any breed. There is an increased frequency of occurrences in in Golden Retrievers, German Shepherds and Rottweilers. Hemangiosarcoma develops slowly over time and is not painful to the dog. The organ most frequently affected is the spleen, which can cause extreme blood loss, with the dog showing signs of shock such as sudden weakness, pale gums, and labored breathing. This tumor also frequently affects the heart, liver and skin.

Osteosarcoma is the most common type of primary bone tumor in the dog. It most frequently affects the long bones in front and rear limbs of the dog, but can be found in any bone including the skull or spinal column, which are more rarely seen. This tumor is usually associated with the large and giant dog breeds, and are most commonly diagnosed in dogs between 2 to 8 years of age. Males are slightly more at risk than females for developing this form of cancer.

Mast cells are immune cells found throughout the body that play an important role in allergic reactions. Most mast cell tumors are found on the skin and may be detected by a sudden swelling or growth. Boxers and bulldogs are more frequently diagnosed with Mast Cell Tumors compared to other breeds. Mast cell tumors account for about 20% of skin tumors.

Melanoma is a tumor made of pigmented or dark skin cells that can be found anywhere on the dog’s body. Any dog can be affected, but dogs with dark skin or hair coats, such as the Scottish Terrier or Doberman Pinscher, are more frequently diagnosed. Melanomas behave differently depending on what part of the body they are found.
Ocular Melanoma

Soft Tissue Sarcoma is a tumor of fibrous tissue, fat, smooth muscle nerves and lymphatic vessels. Soft tissue sarcomas comprise 15% of all skin/subcutaneous (under the skin) tumors. These tumors are typically very invasive to the surrounding tissue but generally have a low risk of spreading.

Treatment

Armed with this information, what do we do? There can be many options and ways to look at treating cancer, but the single most important thing to keep in mind is that you, as the owner, know your dog the best, you want what will be the best option for them with the best quality of life and support, and you are the advocate for your pet. Keeping that in mind with that “full spectrum” approach will help you feel confident and comfortable that you are making the best decisions for your pet family.

When the time comes to discuss treatment options, it can be easy to feel overwhelmed. There are many treatment options out there and your decision on how to best treat your pet may be based upon the grade, stage and type of cancer they have, and what is available in your area. Let’s take a quick look at some of these options, both a conventional and alternative, to help you understand your options for a balanced approach.

Surgery at one time was the only form of treatment for cancer. The goal of surgery is to completely remove a solid tumor. In cases where those solid tumors are localized to a particular organ or site, surgery may be curative. Depending on the tumor type, surgery may be combined with other treatments such as chemotherapy and radiation to target any residual cells left by surgical removal.

Limb Sparing is a surgical procedure that provides an alternative to amputation in selected dogs being treated forbone tumors. The idea of preserving a limb in dogs is not new, but it is only recently that advances in medical technology have made this procedure possible. The goal in limb sparing is to remove the diseased bone and surrounding tissues while still preserving the function of the remaining limb. The piece of diseased bone that is removed is replaced by a combination of healthy bone from a donor and bone graft from other parts of the patient’s body (see the work being done by the Clinical Oncology Service Veterinary Hospital of the University of Pennsylvania).

Immunotherapy is the use of the body’s immune system to treat a disease. Immunotherapy is most effective in treating certain cancers such as melanoma, hemangiosarcoma, and lymphoma, among others. There are various types of immunotherapy, ranging from vaccines to injecting cytokines (chemicals that stimulate the body’s own immune system). One advantage of immunotherapy is that it is generally less toxic then chemotherapy.

Chemotherapy is used to treat cancer at the tumor site, as well as the cancer that may have spread to other parts of the body. Most chemotherapeutic drugs act directly on the cancer cells, preventing them from maturing or reproducing. And unlike humans, the side effects of chemo in pets is relatively mild. The goal with chemo is to slow down the growth of cancer cells, while producing minimal effects on normal cells.

Radiation Therapy is often used in conjunction with surgery or chemotherapy. Radiation therapy is a conventional medical treatment that sends high-energy particles into tumors. These particles interact with the atoms in the DNA of the cancer cells and destroy them. This, in turn, destroys the cancer cells. Radiation also kills healthy cellsthat fall in its path, such as those in the skin, which can also be harmed. A dog must be under general anesthesia to receive radiation therapy and may require multiple treatment sessions.

Cryotherapy is a technique that uses extremely cold temperatures produced by liquid nitrogen to kill the abnormal cells. Usually used to treat relatively small, external tumors such as those on the skin, a local sedation or general anesthesia maybe required.

Photodynamic Therapy (PDT) is a treatment that uses a drug called a photosensitizer with a specific type of light to kill cancer cells. The agent is absorbed by normal cells as well as cancer cells, but stays in cancer cells longer. The tumor is exposed to light after a period of time. The photosensitizer in the tumor absorbs the light and produces an active form of oxygen that destroys the tumor cells. The light needed to activate most photosensitizers is unable to pass through tissue thicker than 1 cm. For this reason, PDT is usually used to treat tumors of the skin or on the lining of internal organ or cavities. PDT is less effective on large tumors, because the light cannot pass very far into the mass. PDT is used for localized tumors and cannot be used to treat metastatic cancer.

Acupuncture treatments are generally given as an adjunct to support western cancer treatments. Acupuncture can reduce the side effects of chemo and radiation. Acupuncture also increases blood circulation to the cells that need to get blood. There is some thought that acupuncture can help to pull blood away from cancer cells and give it to
Acupuncture

the parts that need it. Often times with cancer, the body ends up without enough nutrients and energy because the cancer takes it all, and acupuncture is believed to help reverse this.

Herbal Medicine is the use of botanical remedies. Herbal healing is considered by many to be the oldest form of medicine and has been used by all races, religions, and cultures throughout the world. While most western conventional drugs have one or two specific actions, an individual herb can display multiple actions within the body. When properly administered, herbal medicines generally have far fewer side effects than pharmaceutical drugs.
Herbal medicine is very beneficial in the treatment of cancer. One of the most appropriate and effective uses of herbs is to help reestablish an underlying balance and general state of health of the patient after the patient has been rendered “cancer-free” with conventional therapies. Herbs may also be used as an adjunct to ongoing conventional cancer therapies to offset the side effects of radiation and chemotherapy, enhance the patient’s immune system and aid in tumor reduction itself.

Food Therapy/Nutrition This can be a big part of the complete treatment of cancer in your dog. There are many different “Cancer Diets” out there and a lot of different beliefs in this area regarding raw vs kibble vs home cooked, more protein, less protein etc.

In part 3 of our cancer blog we are going to focus on the question of what kind of nutritional needs your dog may have while going through some of the above palliative treatments or when just keeping him comfortable as long as you can. I strongly believe that some of the nutritional changes I made in my dog McCain’s diet after I found out he had tumors on his liver and spleen gave him a better quality of life and helped him to survive with cancer for many years. So check back!

See Part I