The 5 Most Common Types of Cancer in Dogs

There are two main forms of cancer in dogs: carcinomas and sarcomas. Carcinomas are growths made up of cells. These cells then multiply and cause the cancer to spread. Sarcomas are tumors that come from connective tissue. It's name generally comes from the area where the cancer originated.

Below are the five most common types of cancer found in dogs, as well as the symptoms. Being educated on canine cancers and their symptoms will better help you identify a serious illness in your dog.

1. Hemangiosarcoma

This cancer begins in a dog's blood cells. The most common organs affected are the spleen, skin, liver and heart, although it can be found in almost any part of the body. A tumor that has ruptured will be the cause of severe symptoms in your dog. If the tumor has ruptured near a vital organ, anemia and weakness will occur. The tumor is composed of blood, so a ruptured tumor will result in blood loss and the resulting anemia and weakness. You may be able to detect a tumor before it ruptures by feeling it under the skin or swelling on the bone. The most common breeds affected by hemangiosarcoma are German shepherds, Golden retrievers, Skye terriers, Portuguese Water Dogs and other large breeds.

2. Lymphosarcoma

Lymphosarcoma (or lymphoma for short) affects a dog's immune system. The lymphoid tissues are found in many parts of the body often resulting in metastases. The main symptom is irregularly swollen lymph nodes which can be found in the upper and lower neck, behind the front legs, in front of and behind the back legs.

3. Osteosarcoma

The prefix osteo refers to the bone which is where osteosarcoma originates. Large breeds are highly at risk for osteosarcoma, therefore, owners of these breeds should be aware of the symptoms for early detection. Symptoms include pain, swelling, lack of physical activity and, in severe cases, trouble breathing. Osteosarcoma in its late stages usually spreads to the lungs making breathing and treatment difficult.

4. Mammary Carcinoma

This type of cancer is highest in non-spayed female dogs. It is so common that approximately 25% of all non-spayed female canines will develop mammary carcinoma. While any tumor can be frightening, in over half the cases of mammary carcinoma removing the tumor through surgery is curative.

5. Melanoma

Melanoma can occur in any dog but is most commonly found in dark-skinned canines. It can reveal itself in dark, small lumps or as large wrinkled areas on the skin. Melanoma can be benign or malignant. Benign cases can result in a mass that is not harmful but can be uncomfortable and require removal. Malignant melanoma is incurable. By the time it is detected, it is often too late because it has spread throughout the body making surgery difficult if not impossible. Radiation treatment can extend the life of the dog but will reduce his quality of life greatly. Chemotherapy is not effective in treating melanoma cases.