The C Word - Canine Cancer

September 5, 2017

Did you know that more than half of dogs over the age of 10 are prone to develop cancer? Cancerous tumours are masses of tissue that occur when the cells divide more rapidly than normal or do not die when they should.

Because tumours can develop from any tissue, there are many types of tumours that can occur in various locations.


Treating Canine Cancer

Most treatment plans for canine tumours involve surgical removal of the tumour and some involve treatments such as Chemotherapy. Chemotherapy drugs work by damaging rapidly dividing cancer cells while sparing normal cells. Because of this, normal tissues that also rapidly divide, such as those found in the intestine, bone marrow, and hair, can also be affected by chemotherapy.


Chemotherapy protocols are very different for dogs than to humans that are undergoing such treatments. The doses of chemotherapy are lower in dogs than in people, and side effects are much less common.



Common Types of Cancer in Dogs

So what are some of the common types of cancer in dogs? This list should give you a more thorough understanding of this disease.



Lymphoma is among the most common type of tumour seen in dogs, representing 20 percent of all canine cancers. Currently, dogs are 5 times more likely than people to develop lymphoma. This tumour can affect any breed of dog at any age. Signs of lymphoma vary depending on the location of the disease. Peripheral Lymphoma: The most common sign is enlargement of the lymph nodes. Signs include large lymph nodes, a decreased appetite or lethargy. Internal Lymphoma: This is another form of lymphoma which affects the internal lymph nodes that are made of similar lymphoid material such as the liver or spleen. Signs of internal lymphoma are vomiting, diarrhea, abdominal pain, or difficulty breathing. Treatment options for lymphoma consist of either a single drug such as prednisone or multi-drug chemotherapy.




Hemangiosarcoma is a tumour that develops from cells that line blood vessels. This tumor most commonly affects middle-aged or older dogs of any breed. Hemangiosarcoma develops slowly over time and is not painful to the dog. Signs usually do not show up until late in the disease, when the dog suffers from internal bleeding due to the tumor rupturing. The organ most frequently affected is the spleen, which can cause blood loss, with the dog showing signs of shock such as sudden weakness, pale gums, and labored breathing. Treatment usually involves surgery to remove the spleen and control bleeding, with recommendations for chemotherapy starting 2 weeks later.




Osteosarcoma is the most common type of primary bone tumour in dogs affecting the long bones. Osteosarcoma is an aggressive and rapidly spreading tumour and it is recommended that the affected bone is to be amputated followed by chemotherapy.



Mast Cell Tumour

Mast cells are immune cells found throughout the body that play an important role in allergic reactions. Most mast cell tumours are found on the skin and may be detected by a sudden swelling or growth. The mast cells contain small granules that make them fairly easy to diagnose with a simple needle aspirate (FNA). Treatment for mast cell tumors depends on the location of the tumor and how the tumor looks when removed and biopsied. Sometimes, the recommendation is surgery alone. Mast cell granules contain histamine, which can be irritating to the dog’s intestinal tract, so the vet may recommend long-term treatment with antihistamines to counteract this problem.




Melanoma is a tumour 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, are more frequently diagnosed. Melanomas act differently depending on which part of the body they are affecting. Tumors located in the mouth, on the feet, toes and limbs are usually associated with a worse prognosis. Treatment for melanoma’s include surgery, radiation therapy, and chemotherapy.



Squamous Cell Carcinoma

Squamous cell carcinomas can develop on the skin and inside the dogs mouth. Growths on the skin are often detected early and response rate very good. Tumours in the mouth are very difficult to remove and can grow quite large prior to being detected and as a result, considered very aggressive.



Mammary Carcinoma

Tumours of the mammary glands are the most common tumour seen in unspayed female dogs. They can affect any of the mammary gland and may behave locally and respond well to surgery. Around 50 percent of these tumors are malignant, meaning they have spread to other locations—primarily the lungs or lymph nodes—at the time of diagnosis. Treatment usually involves surgery of the affected gland or removal of the entire chain of mammary glands on the affected side along with the lymph nodes. Chemotherapy is recommended in cases where the tumor has spread to other areas.



Apocrine Gland Carcinoma

Apocrine gland carcinomas are also known as carcinomas of the anal sac in the dog. Anal sac carcinomas are described as locally invasive, meaning they grow and invade tissues around the anal gland. This can make complete surgical removal difficult. Chemotherapy and Radiation therapy is also recommended.



Transitional Cell Carcinoma

Transitional cell carcinoma is the most common tumour of the lower urinary system in dogs. This tumor is considered locally invasive and is highly likely to metastasize to another area. Much like the tumours of the anal gland, surgical options are dependent on the location, and often, these tumors cannot be completely removed. In such cases, chemotherapy or even anti-inflammatory drugs may be recommended.



Soft Tissue Sarcoma

Soft tissue sarcomas are a group of several different types of tumours that share similar characteristics. These tumours are made of connective tissue and are located either within the skin or in tissues just below the skin. Soft tissue sarcomas are locally invasive, with the spreading of cancerous cells into adjacent normal tissues. As a group, soft tissue sarcomas have a 40 % chance of spreading to other areas of the body. Treatment depends on the location of the tumour and whether there has been metastasis at the time of diagnosis. Surgery, chemotherapy, and radiation therapy have all been used to treat this tumour type. 



Overall, about 60% of canines that get tested for cancer are malignant. There are still a lot of canine's with just lumps and bumps that vets are removing and as a result, these canine's have an excellent long-term prognosis.


However if the cancers are left untreated, we’re talking survival times in the months, not years.




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