What Should I Know About Canine Cancer?
A cancer diagnosis will ultimately affect the lives of half of all dogs who reach 10 years of age. And, each specific canine cancer-type creates its own unique negative health impacts. However nearly all canine cancers, and even many cancer treatments, produce similar impacts on dogs’ immune, digestive, integumentary and other physiologic systems. These common impacts often limit their ability to maintain weight, avoid cachexia, benefit from cancer treatments and thrive.
You are not alone. Many people are dealing with the same questions and concerns that you are. Approximately 500,000 dogs are diagnosed with cancer each month.
How Common Is Canine Cancer?
Approximately 500,000 dogs are diagnosed with cancer each month in the US alone. It is estimated that 50% of all dogs over the age of 10 years will ultimately face a cancer diagnosis. In fact, canine cancer is the leading cause of death in dogs. But the good news is that canine cancer is becoming more treatable all the time. Modern methods of caring for our furry friends can improve their quality of life. And dogs diagnosed with cancer and their owners have more options than ever before.
What Types of Canine Cancer Are There?
The 5 most common cancer types in dogs are:
Mast Cell Tumors - a form of skin cancer
Melanoma - tumors in the mouth and skin
Lymphoma - cancer of blood cells and lymphoid tissues
Osteosarcoma - bone cancer
Hemangiosarcoma - rapidly spreading cancer causing tumors anywhere in the body, especially in the heart and spleen
Scroll down for more on specific cancer types.
How Long Can Dogs Live With Cancer?
More specific tests are available for some cancer types that may provide a more precise prognosis for dogs with those cancers. Consult your veterinarian or a canine oncologist to determine your dog’s prognosis, both with and without treatment. This information can be an important input in deciding if and how to treat your dog.
How Does Cancer Affect Dogs
Cancer can affect dogs in many ways from mild to severe. But don't forget that your dog often looks to you as to how they should be feeling. They know you love them but it helps to also remain as upbeat and optimistic as possible - your dog will feel it.
As to the exact symptoms, they may include: lethargy, upset of their digestive system, weight loss, lameness, rapid heart rate and breathing, localized tenderness, unusual discharge, pain, swelling or lumps and, many times, your dog will exhibit little to no outward sign that they are feeling ill.
Your veterinarian will help you manage your dogs symptoms...but, look for changes. It is a good idea to keep a journal of what you observe so that changes in symptoms and, more importantly, new symptoms can be tracked and assessed.
Deciding To Treat Your Dog
This is a very personal, and often difficult, decision for any dog owner to make. Each owner of a dog with cancer will ultimately consider a variety of factors and weigh them differently. Factors may include the dog’s current quality of life, pain level, relationship to and role within the family, prognosis for longevity and different costs for a variety of approaches to treatment.
Consult with a veterinarian or canine oncologist, talk with your family and give yourself the time and space to make a decision that you can be personally satisfied with. And remember, every dog owner will approach making this decision differently. Give yourself the freedom to do what you believe is best for you and your dog; your decisions and plans are a reflection of you and your dog’s situation and may be very different than how other owners would decide and act on behalf of their dog’s unique situation.
The Role of Nutrition
For dogs undergoing treatment for cancer such as surgery, chemotherapy, radiotherapy and immunotherapy, and even for those dogs whose owners are just managing the pain level of their pets, complete and balanced nutrition is key to maintaining their quality of life.
A complete and well integrated nutrition plan can support dogs by helping them to continue to maintain their appetite, receive the benefits of the nutrients in their diet and maintain their weight and muscle mass so that a higher quality of life can be enjoyed. Nutrition which includes the right proteins, amino acids, vitamins, minerals and other compounds can reduce inflammation and degradation of the lining of the gastro-intestinal system. These conditions often accompany cancer (and sometimes result as side effects of treatment) which can make it difficult for dogs to thrive due to lower nutrient uptake and retention.
In addition to these important components, the proper amounts, types and ratios of fat, protein and complex carbohydrates may have a great impact on the benefit that your dog's diet can add to the mix.
Specific Cancer Types - Details
Leukemia or lymphoma
This is a cancer that affects the white blood cells.
A particular type of white blood cell, called a lymphocyte, is usually involved. Lymphocytes circulate in the blood and also in the lymphatic system, which is a system of vessels and centers (swellings called lymph nodes are often referred to as glands). This is where the body screens for infections and other foreign bodies that may be attempting to enter the system. When lymphocytes become cancerous, their numbers increase uncontrollably. The lymphocyte count in the blood may rise, but often the lymphocytes sit in one place and multiply. This can cause enlargement of one or more lymph nodes, producing lumps in the throat area or other parts of the body, or it may involve internal organs, such as the liver, spleen or bowel. The cancerous lymphocytes can easily spread to other parts of the body through the blood circulation or the lymphatics (the tubes that connect the lymph nodes).
Because lymphoma is often widespread, surgery alone is not usually appropriate. Untreated, the average survival time from diagnosis is about two months. This can be prolonged with chemotherapy (in some cases for 12 months or occasionally longer), although unfortunately not all lymphomas respond successfully. Survival expectations are something you should discuss with your veterinarian, as these differ depending on the part of the body affected.
Many of the lumps that occur in the skin are benign and can be surgically removed. Occasionally, there may be obstacles to removal if the lump is very large, or in an area where repairing a surgical wound is difficult. This is something your veterinary surgeon will discuss. Unfortunately, there are some cancerous types that recur in the same place and a few that spread to other sites in the body. Biopsies may be helpful because if an aggressive tumor is identified, cutting out a larger area of skin may reduce the likelihood of recurrence or spread.
Dogs have five breasts on each side of the tummy, visible as two rows of nipples, and tumors may occur in one or more. About half of these tumors are benign. The choices for surgery are removal of the lump alone, or removal of some or all of the rest of the breast tissue. Removing more tissue does not appear to prevent internal spread of cancers. These often spread to the lungs, so chest x-rays are advisable prior to surgery, although early spread may not be visible. If not already done, spaying a bitch at or after breast surgery may reduce the chance of recurrence.
Mast Cell tumors
A cancer usually found in the skin.
Mast cell tumors in dogs are not unusual and may account for 20% of all skin tumors in dogs. The underlying cause(s) for the development of the tumor is not known. Mast cell tumors can arise from any skin site on the body, and may exhibit a range of appearances.
Veterinary oncologists recommend that before any skin lump is removed, a sample should be collected to rule out the mass as a mast cell (or other malignant) tumor. Mast cells are something that are easily identified. Treatment may range from chemotherapy to surgery to radiotherapy or a combination of these. Choices are based on the grade and location of the tumor. Keep in mind that mast cell tumors are often quite treatable.
Additional Cancer Types
Another skin cancer type in dogs is malignant melanoma.
This type of cancer - like many others - is common to both dogs and humans. And, these are in fact the most common type of tumors found in dogs. Caught early they are very treatable. Dogs with light-colored or thin coats are more susceptible to sun damage over their entire bodies and therefore may develop these tumors at a higher rate.
Most malignant melanomas occur on the mouth or mucous membranes, although about 10% of the time they are found on parts of the body covered with hair. They tend to grow extremely fast and are likely to spread to other organs, including the lungs and liver. As with mast cell tumors, treatment may range from chemotherapy to surgery to radiotherapy or a combination of these. Choices are based on the grade and location of the tumor.
Osteosarcoma in dogs is a primary bone tumor.
This cancer most often is found in the bones of the limbs but can develop in the bones of the skull, spine or rib cage and there are rare cases of this tumor arising in non-boney tissues like mammary glands and muscle. Osteosarcoma is most often seen in large breeds. Two that are very susceptible are Rottweilers and Irish Wolfhounds though St. Bernards, Bernese Mountain Dogs and other so called giant breeds suffer it all too often and sometimes at quite young ages.
Unfortunately, this type of cancer can spread rapidly and result in secondary tumors. If the primary tumor is in a limb, amputation is a common surgical intervention followed by chemotherapy and, often, radiotherapy as well. If caught early, and with a combination of treatments applied, survival times can run beyond one year with many dogs surviving to two years or even more.Hemangiosarcoma
Hemangiosarcoma is characterized by rapidly spreading tumors anywhere in the body, especially the lining of blood vessels, the skin, spleen and right atrium of the heart.
This cancer, though only affecting abut 7% of all dogs with cancer, is particularly insidious. In about 80% of cases, it has already spread (metastasized) before it is diagnosed. This accounts for its, usually, very short prognosis. However, if it starts in the skin, it can have a more positive outcome..