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Dog Cancer - Symptoms, Diagnosis & Treatment


At Countryside Veterinary Clinic, we understand that your canine companion is not just a pet but also is a beloved, cherished family member. The mutual bond of love and loyalty between you can make a diagnosis of any form of dog cancer very difficult to hear. Our veterinarians and support staff are empathetic, compassionate, and trained to focus on both the emotional and medical aspects of dog cancer.

We are here to guide you both through the diagnosis and treatment process. This includes choosing the best options for effectively, humanely, and successfully dealing with canine cancer.

Common Types Of Cancer In Dogs

Cancer is caused by the uncontrolled growth of cells in the body. These cells can originate in any of the body's tissues. If not found and arrested in time, cancer can expand and connect with the circulatory or lymph systems, and it also can spread and infect other tissues in the body. Canine cancer is the leading cause of death for dogs 10 years of age and older. However, half of all cancer in dogs is treatable if it is arrested in its early stages.

The most common types of cancer in dogs are:

  • Hemangiosarcoma: This form of dog cancer is a tumor of the cells that line blood vessels, called endothelial cells. Although dogs of any age and breed are susceptible to hemangiosarcoma, it occurs more commonly in middle-aged or elderly dogs. Also, certain breeds have a much higher incidence, including Golden Retrievers and German Shepherds. This form of dog cancer develops slowly and is essentially painless, so clinical signs are usually not evident until the advanced stages when it is first noticed. The most common clinical sign is an enlarged spleen diagnosed by palpation or through radiology or ultrasound. This spleen can be surgically removed and then biopsied to determine if the tumor is benign or malignant. Further medical treatment may be discussed.
  • Mast Cell Tumors: These are immune cells that are responsible for allergies. Mast cells can be found in all tissues of the body but typically form tumors on the skin in close to 20 percent of the canine population. They range from relatively benign to extremely aggressive. Certain breeds of dog are at an increased risk for the development of this tumor, indicating that genetics might be a cause. Boxers are especially prone to this type of cancer.
  • Lymphoma: This form of dog cancer can affect any dog of any breed at any age. Most of the time, it appears as swollen glands (lymph nodes) that can be seen or felt under the neck, in front of the shoulders, or behind the knee. Occasionally, lymphoma can affect lymph nodes that are not visible from outside the body, such as those inside the chest or in the abdomen. This can cause trouble breathing and digestive trouble. Generally, this form of dog cancer is considered treatable if arrested in its early stages. Standard Poodles, Golden Retrievers, and Australian Shepherds are a few of the breeds with a higher incidence of lymphoma.
  • Osteosarcoma: This form of dog cancer is the most common type of primary bone cancer in dogs, accounting for up to 85% of tumors that originate in the skeletal system. Although it mostly affects older large or giant breed dogs, it can affect dogs of any size or age. Osteosarcoma occurs in many areas, but it most commonly affects the bones bordering the shoulder, wrist, and knee. Major symptoms include lameness in the affected leg or a swelling over the area that seems painful at the site.
  • Brain Tumors: Epileptic-like seizures or other extreme behavioral changes can be clinical signs of brain tumors. CAT scanning and MRI are used to determine the location, size, and severity. Although oral chemotherapy and radiation therapy can control some inoperable tumors, surgical intervention may be recommended if the tumor is operable.
  • Bladder Cancer: Some breeds are more at risk for this form of dog cancer than others. This is a slow-developing dog cancer, and symptoms may not show for 3 to 6 months. Urinary obstruction and bleeding are common symptoms.
  • Mammary Carcinoma: Non-spayed female dogs are at high risk for developing malignant mammary tumors, but all female dogs regardless of reproductive state remain at risk. Approximately 50% of these tumors are malignant, and complete surgical removal is recommended if the cancer has not metastasized.
  • Malignant Histiocytosis: This dog cancer affects larger sport breeds most often. It occurs as localized lesions in the spleen, lymph nodes, lung, bone marrow, skin and subcutis, brain, and periarticular tissue of large appendicular (limb) joints. Histiocytic sarcomas can also occur as multiple lesions in single organs (especially spleen) and rapidly disseminate to involve multiple organs. Unfortunately, there is no reported effective therapy for this form of dog cancer.
  • Squamous Cell Carcinomas (SCC): This is most often found in the mouth and the nail beds of the toes. Early detection and complete surgical removal is the most common treatment. Fewer than 20% of dogs develop metastatic disease. SCCs of the tonsil and tongue are quite aggressive, and fewer than 10% of dogs survive one year or longer despite treatment measures.
  • Mouth and Nose Cancer: This is a very common form of dog cancer, more so in the mouth than in the nose. Symptoms include a mass on the gums, bleeding, odor, or difficulty eating. Since many swellings are malignant, early, aggressive treatment is essential. Cancer may also develop inside the nose of dogs. Bleeding from the nose, breathing difficulty, and/or facial swelling are symptoms that may indicate nose cancer.
  • Melanoma: This form of dog cancer most commonly occurs in canines with dark skin. Melanomas arise from pigment-producing cells called melanocytes, which are responsible for coloring the skin. Melanomas can occur in areas of haired skin, where they usually form small, dark (brown to black) lumps, but they can also appear as large, flat, wrinkled masses. Malignant melanoma, which develops in the mouth or in the distal limbs (usually the toenail beds), is an incurable disease. These tumors have very often spread to distant parts of the body by the time they are first noticed, making complete surgical removal impossible.
  • Testicular: This form of dog cancer is common in unneutered dogs with retained testes. Testicular dog cancer is largely preventable through neutering and curable with surgery if arrested early in the disease process.

Symptoms And Signs Of Cancer In Dogs

Some signs of cancer in dogs are easy to spot while others are not. The signs of cancer in dogs may vary greatly depending upon a number of factors. However, the following list identifies some of the most common signs of cancer in dogs:

  • Lumps and bumps underneath a dog's skin
  • Abnormal odors emanating from the mouth, ears, or any other part of the body
  • Abnormal discharge from the eyes, mouth, ears, or rectum
  • Abdominal swelling
  • Non-healing wounds or sores
  • Sudden and irreversible weight loss
  • Change in appetite
  • Coughing or difficulty breathing
  • Lethargy or depression
  • Changes in bathroom habits
  • Evidence of pain

Should you witness any signs of cancer in your dog, we strongly recommend making a veterinary appointment immediately.

What You Need To Know About Tumors In Dogs

Tumors in dogs usually appear as fleshy but solid lumps of tissue underneath a dog's skin and fur. Not all tumors will be outwardly evident. Sometimes you can see evidence of tumors, and sometimes they are deep within the body of the dog. However, early detection and treatment are key to preserving your dog's health and quality of life. Therefore, it is important to periodically inspect your canine companion for any abnormal lumps and schedule a veterinary appointment if necessary.

Owners most commonly find a tumor on their dog while petting or bathing. If you are running your hand over any part of your dog's body and feel a lump, call to make an appointment with your veterinarian. Most likely, the veterinarian will want to do a needle aspirate to get cells from the tumor to get a diagnosis on the type of tumor. The diagnosis is helpful in determining what if any type of surgery and or follow-up cancer care may be necessary. Some tumors in dogs cannot be visualized but can be palpated (felt with touch) by your veterinarian during the exam. For instance, an enlarged spleen may be palpable to your veterinarian but not visible to the owner. You can reference the list of canine cancer symptoms above to get a better understanding of what symptoms to be on the lookout for.

Diagnosing Canine Cancer

Please mention any unusual lumps or bumps or concerns during any illness or wellnes exam. Diagnosing and treating canine cancer before it advances is key to successful recovery.

Treatment Options For Dogs With Cancer

Several factors influence cancer treatment decisions for dogs with cancer, including:

  • The age of the dog
  • The general health of the dog
  • The tumor type
  • The biological behavior of the tumor
  • The stage of the cancer

Overall health status plays a major role in the therapy choices for dogs with cancer. This includes evaluating the dog's ability to tolerate cancer treatment.

Treatments for dogs with cancer are similar to human therapies, which can include:

  • Chemotherapy
  • Surgery
  • Radiation therapy
  • Holistic or herbal therapy

Sometimes, combining methods work well for dogs with cancer.

Make An Appointment Today If You Suspect Dog Cancer

If you suspect dog cancer, whether finding a bump or witnessing behavioral symptoms, please contact us to schedule an appointment. Our veterinarians and support staff will provide you and your canine companion with compassionate, comprehensive dog cancer care and support services. Although dog cancer can be overwhelming, you don't have to go through it alone. We are here to help ease your dog's pain and suffering and eliminate the cancer through the best dog veterinary care available.

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