Sunday, September 15, 2019

Dog Cancer Types, Symptoms and Treatments


Cancer can cause a lot of pain and discomfort to our pets. Cancer is one of the most common natural causes of death in dogs. For dogs over 10 years of age, approximately 50% of deaths are cancer related. However, not all cancers carry a poor prognosis. The key is to educate ourselves  on different types of common dog cancer and their clinical signs, and be more observant for changes in our dogs’ behavior and physical conditions. Knowing and recognizing the symptoms of canine cancer will help dog owners seek medical attention earlier, and coupled with the cutting edge care, help the dog survive longer.

What is Cancer?

Cancer is defined as any malignant, cellular tumor, or uncontrolled growth of cells and may be benign or malignant. All forms of cancer start when there are atypical gene mutations in some susceptible cells. These mutated cells then begin to reproduce and attack other normal, healthy cells. When these atypical cells take over enough normal cells, cancerous tumors form. This process continues until there is not enough normal tissue remaining to sustain normal bodily functions.

Causes of Cancer

The exact causes of dog cancer are still unknown. All forms of cancer start by genetic mutations that convert normal cells into cancer cells. It is believed that mutations are usually caused by chronic inflammation or excessive oxidation.

If we look at our environment, it is not difficult to find a lot of substances that may cause inflammation or excessive oxidation in our dogs’ bodies (and ours too):

  • Polluted air (e.g. cigarette smoke, gas exhaust) and water.
  • Toxins and harmful chemicals found in some common products (e.g. pesticides, household cleaners, dog flea products, etc.).
  • Low-quality dog foods and treats that contain artificial colors, flavors, additives, and/or preservatives.
  • Radiation – It has been found that dogs, like people, are more susceptible to cancer development if they are frequently exposed to radiation of various forms


Little is known about how to prevent cancer in our pets. Once the underlying causes of the various cancers are ascertained, prevention will become more realistic. We do know that spaying or neutering can reduce the risk of testicular and mammary gland cancer in domestic dogs.

Another good first step of prevention is to research the breed of dog before you decide on which breed you will adopt and only adopt from a reputable dog breeder.

The next step of prevention is to make sure your dog has good nutrition. A high quality dog food made by a reputable company, or a home prepared diet recommended by your Veterinarian.

Plenty of exercise is essential for a dog’s physical and emotional well being. Overweight dogs may be cute, but a fit, healthy dog will be less likely to develop canine cancer. Adding omega-3 fatty acids to your dog’s diet potentially reduces the risk of cancer also.

Clean living and avoidance of environmental pollutants is as important for your dog as it is for you. Eliminate any potential health hazards from your dogs environment, such as pesticides, herbicides, coal or kerosene heaters, asbestos, etc.

Breeds Prone to Cancer

Cancer is seen more often in some breeds more then others. The Golden Retriever is the breed most prone to cancer. It is estimated that up to 75% of Golden Retrievers will contract cancer during their lifetimes with lymphoma and hemangiosarcoma or cancer of the blood vessels and spleen being among the most common.

Other notably breeds include the Boxer, Bernese Mountain dogs, Greyhounds, Rottweilers, Great Danes and German Shepherd.

Symptoms of Cancer

One of the most common signs of cancer in dogs is the appearance of a lump or mass. Usually, the dog does not seem to notice or be bothered by the lump. However, while it may or may not be malignant, any mass is abnormal and should be evaluated by a veterinarian. Other signs of cancer are:

  • Superficial or subcutaneous skin masses
  • Weakness
  • Lethargy
  • Fatigue
  • Lack of appetite (anorexia; inappetance)
  • Vomiting
  • Enlarged lymph nodes
  • Diarrhea
  • Weight loss
  • Pale mucous membranes
  • Lameness, swelling around leg joints, pain (osteosarcoma)
  • Fever
  • Collapse
  • Spontaneous bleeding (hemangiosarcoma)


The goals of treating cancer are to prevent further metastasis (spreading), removing all cancerous tissue when possible and restoring the dog’s quality of life. There are many different type of cancer treatment: surgery, chemotherapy, radiation or any combination of these treatments. The important thing is to destroy the abnormal cells without damaging the normal cells. The veterinarian will use this information to assess the outlook for the animal and to establish a prospective course of action. Owners can expect to see some side effects in their dogs from any treatment, including possible nausea, vomiting, diarrhea, weakness, lethargy and lack of appetite.

Special Note

Early diagnosis of cancer can greatly improve the prognosis. With prompt diagnosis, aggressive treatment and ongoing management, many dogs with cancer go on to live long, comfortable and relatively normal lives.

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