Dog Cancer Symptoms


"Dog cancer symptoms tend to be common to many types of canine diseases. Cancer is an emerging health issue and is of great importance since it is life threatening in most cases. Some dogs are genetically predisposed to it, while others may acquire it from pathogens (disease -causing), toxins, drugs, or as a complication of some common health problems."


Canine cancer symptoms are highly non-specific and resemble many common health problems in the initial stages of the disease. Unfortunately, once the cancer is identified as the cause it is often incurable, since it will be in a more advanced stage. Both benign (slow spreading) and malignant (fast spreading) forms of dog cancers can be result in severe symptoms, benign tumors are less dangerous. Clinical studies show that dog cancer symptoms are exhibited in two different phases, initially mild, while recurring and severe in advanced stages. Dog cancer symptoms are only helpful in suspecting that cancer is the cause and not that helpful. Only detailed laboratory and pathological sampling can confirm the presence and extent of the disease. Along with specific treatment through surgery, chemotherapy, and the application of radiation, symptomatic therapy can help in improving the quality of life in the affected dog. Incurable dogs are usually kept on lifelong symptomatic treatment plans only.

General Dog Cancer Symptoms

Dog cancer symptoms are highly non-specific, and while any dog can acquire cancer, older dogs and females are more susceptible. Similarly, some breeds such as boxers, terriers and retrievers, etc. are potentially predisposed to cancer genetically. Dogs with a malignant (fast spreading) form of cancer show more severe and generalized symptoms, while those with benign (slow growing) tumors/cancers usually show no or less symptoms initially, but the severity increases gradually.

Generally, a dog with cancer appears dull, non-social, anorexic (appetite loss), ataxic (uncoordinated muscle movement), intolerant, and gradually loses weight. Any of these symptoms usually do not help in making a confirmatory diagnosis, as these symptoms may be seen in many other health problems of dogs. Involvement of a specific part, system, or organ of the body can help to some extent to suspect dog cancer as the underlying cause.

The Veterinary Cancer Society publishes a helpful list of common cancer symptoms in small animals. These include:

  1. Abnormal swellings that persist or continue to grow
  2. Sores that do not heal
  3. Weight loss
  4. Loss of appetite
  5. Bleeding or discharge from any body opening
  6. Offensive odor
  7. Difficulty eating or swallowing
  8. Hesitation to exercise or loss of stamina
  9. Persistent lameness or stiffness
  10. Difficulty breathing, urinating, or defecating

Systemic Dog Cancer Symptoms

Dog cancer can appear at any part of the body, and can be caused by any number of factors as pathogens such as viruses, high doses or prolonged use of some drugs, extreme defects in physiology, etc. Age is also a significant factor in the development of dog cancer.

Different organs/systems such as the bladder, liver, pancreas, intestines, lungs, spleen, mammary glands, testes, or bone marrow can be the site of a dog cancer. Similarly the lymphatic system, musculoskeletal system, circulatory system, and urinary system are the most commonly affected parts of a dog's body and are responsible for almost all types of malignant forms of cancer. Lymphomas (lymphatic tissue), hemangiosarcomas (bleeding in the heart, liver, spleen, and skin), and osteosarcomas (bone) are some examples of such deadly dog cancers.

Specific dog cancer symptoms that are related to affected organs or systems are sometimes helpful in making a diagnosis. Difficulty in urination, abdominal pain, bleeding through open cavities (ears, nose, anus etc), unusual growths and lumps on the dog's body which grow larger with time, recurring vomiting, incurable diarrhea , etc. are somewhat specific signs for dog cancer.

One most common findings which leads to the suspicion of a dog cancer is the recurrence and incurability of symptoms, even if symptomatic treatment has been applied. Ulcers are the best example, which are related to abdominal pain. Ulcers that recur even after symptomatic treatment, can cause the passing of blood into the feces and may develop into an incurable malignant form of dog cancer.

Dog Cancer Symptoms and Diagnosis

Canine cancers which occur on the surface of the skin, such as dog skin lumps or lesions can be diagnosed symptomatically, but confirmation usually requires a biopsy (tissue sample and lab test) and detailed studies. Dog cancers which occur in deeper tissues and systems can be suspected based on a dog's history and clinical symptoms, but can never be confirmed this way.

Different procedures involving pathological sampling, biopsy, biochemical profiling, and radiography can only confirm the type, severity and possible outcome of the dog cancer.

Treatment of Dog Cancer Symptoms

After confirmation of the disease, a veterinarian usually decides the prognosis or possible outcome of condition. Treatment of dog cancer is purely dependent upon the prognosis. Specific treatment options for dog cancer are surgical excision of the tumors, use of chemotherapy (anti-cancerous drugs) or application of radio waves to eliminate it. Along with specific treatment and to counter the side effects of treatment, symptomatic and supportive treatment options are highly recommended. These may include pain management, approaches to resolve weight loss and stamina , and supportive therapies with balanced diets and supplements.

Some incurable dog cancer cases are kept on a symptomatic treatment approach only. Symptoms such as vomiting, pain, anorexia, and resolution of body conditions are usually managed by administering relevant drugs. Similarly, regular detoxification and maintenance of body conditions or cellular health is required, which can be done with specific prescription drugs or through herbal/homeopathic medicines such as an over-the-counter natural antioxidant. These options should be decided by a veterinarian, as different dogs respond differently.


Morrison, Wallace B. “Cancer in Dogs and Cats” –1998

Merck Veterinary Manual (Merck & Co. 2008)

Washington State University College of Veterinary Medicine