According to the Texas A&M Veterinary School, dogs have 35 times as much skin cancer as humans, four times as many breast tumours, eight times as much bone cancer and twice as high an incidence of leukaemia. Because cancer is so common in dogs, it is important to watch for the signs of cancer in order to begin treatment. And when treatment isn't an option, you should be educated about the end stages of canine cancer.
Lymphoma is one of the most common cancers in dogs. This malignant cancer affects the lymph nodes and the lymphoid system, causing round, hard lumps on the dog's abdomen, back, neck or armpit. In the final stage of lymphoma, Stage 5, the cancer spreads to the bone marrow. Dogs experience a decreased appetite, dramatic weight loss, diarrhoea and vomiting, as well as lethargy, depression and difficulty breathing. Certain types of lymphoma can cause redness or flakiness of the skin, ulceration near the lips and footpads, itchiness and lumps on the skin.
This aggressive, high-grade soft tissue cancer preys on cells that line the blood vessels and can spread rapidly, causing tumours almost anywhere as it makes blood blister-like formations which disrupt normal organ function. While a common cancer in dogs beyond middle age, hemangiosarcoma is virtually a silent killer, as it is generally not detected until the advanced stage. Most dogs die from severe internal bleeding, but visible bleeding that cannot be stopped, usually in the form of nosebleeds, are a good indication of this form of cancer. In the advanced stage, dogs will suffer from signs associated with blood loss, including tiring easily, weakness, pale mucous membranes in the eyes and mouth, abdominal swelling and depression.
This malignant and highly aggressive bone cancer commonly affects the bones of dogs. The bone tumours can cause lameness and pain and swelling may be come obvious as the tumour size increases. In the latter stage, the cancer has typically spread beyond the initial site and the dog experiences pain, which can cause irritability, loss of appetite, weight loss, aggression, whimpering, crying and sleeplessness.
Like female humans, female dogs have mammary glands. These mammary glands can develop breast cancer, particularly if the dog was not spayed before her first or second heat period. In fact, dogs left un-spayed are seven times more likely to get breast cancer than those that are spayed, due to a hormonal influence that causes point mutations in the breast tissue cells. End stage mammary cancer includes large or extremely invasive tumours, sarcomas and spreading to other portions of the body. Symptoms of the final stage include swelling and abnormal growths that are shaped irregularly, bleed or ulcerate. Additionally, the dog may experience coughing, loss of appetite and difficulty breathing.
Mast Cell Cancer
Mast Cell Tumors are a common, malignant tumour in dogs caused by Mast Cell Cancer. Mast cells are the cells in the immune system that are responsible for allergies. The tumours can be found in all tissues of the body but typically form tumours on the skin, appearing as raised, nodular masses that can be either soft or hard when pushed on. These tumours are the most obvious sign of late Mast Cell Cancer and can appear in groups of large lumps on the surface of the skin. Most commonly found on the head and neck, they appear swollen, ulcerated and sometimes are painful. One indication of Mast Cell Cancer is when the tumours randomly change shape or size, even on a daily basis. In the late stage of this cancer, the dog may experience loss of appetite, vomiting, abdominal pain, lethargy, anorexia and laboured breathing.
Squamous Cell and Melanoma Skin Cancer
Skin cancers account for the most common tumours in dogs, occurring mostly in dogs middle-aged to older. Skin cancer can be on the surface of the skin (superficial) or under the skin (subcutaneous) and ranges from benign to malignant, so it is important to check the dog's skin consistently to be aware of any skin changes. In the later stages of Skin Cancer, the dog will begin to show tumours, which may change colour, become scaly or crusty or bleed easily. Depending on the location and how far the tumour has progressed, dogs may experience vomiting, loss of appetite, lethargy, bleeding, delayed wound healing and enlarged lymph nodes.