Cancer in dogs

What is cancer in dogs?

Just like us humans, our dogs are at risk of developing cancer. They are different to most animals in that they can develop all the same types of cancer as humans (cats do develop cancer but not every type). Canine cancer is a very serious and present concern within the canine world. Approximately 1 in 4 dogs will develop some kind of tumour within its lifetime whilst over half the dogs aged 10 or older die from cancer.

To explain this, one first has to talk about Neoplasia. This is when there is an abnormal growth of cells or tissues in the body. The actual growth/lump is known as a neoplasm and can be benign (when the neoplasm does not spread) or malignant (when the neoplasm aggressively grows, spreads and takes over other surrounding cells and tissues). It is these malignant neoplasms that are cancers. In addition, the term ‘tumour’ refers to the bodily manifestation of a neoplasm (this is usually swelling) and so a tumour that is benign isn’t cancer.

What are the symptoms of cancer?

As with any cancer there are a number of early signs that if spotted early enough, can greatly help with the detection and treatment of any cancerous growths. The Veterinary Medical Association states that there are 10 signs that you as a dog owner can look out for. These are as follows:

  • Abnormal swellings that persist or continue to grow
  • Hesitation to exercise or loss of stamina
  • Bleeding or discharge from body opening
  • Sores that do not heal
  • Difficulty breathing, urinating, or defecation
  • Difficulty eating or swallowing
  • Loss of weight
  • Loss of appetite
  • A strong, foul odour
  • Constant lameness or stiffness

How is cancer diagnosed?

If a dog is showing one or more of these symptoms and a veterinarian suspects cancer, then he or she will ask for a number of tests to be undertaken in order to determine if it is indeed cancer. A Biopsy (this is when a part of the body tissue is removed and examined) will be key in investigating and confirming if Neoplasia is present and whether or not it is benign (non-cancer) or malignant (cancer). Other tests that may be undertaken include blood tests, radiographs (x-rays), ultrasounds and in certain cases testing of the lymph nodes (to ascertain how far the cancer has spread).

What causes cancer in dogs?

Whilst there is no actual explanation for the onset of cancer in dogs there are various factors that are thought to contribute to the development of it. Such factors can be prolonged exposure to the sun, certain infections, viruses and chemicals within the environment.

How is it treated and managed?

Each cancer that affects a dog is very specific to that dog’s body, cell and tissue make-up and as such the treatment for each individual case can vary greatly. Chemotherapy, immunotherapy, radiation, cryosurgery, hyperthermia and surgery can all be used as treatment. Treatments may be used on their own or some may be used in conjunction with each other, again, it all depends on the individual canine. The success of the treatment depends upon how aggressive it is, how far the cancer has spread and what type of cancer it is.

A dog suffering with cancer is a horrible thing to have to deal with but if it is caught early enough there is at least some hope.

Please be aware that this guide is for information purposes only. It is not a medical document and if you are worried that your dog may have cancer or any other type of illness then you should contact your vet immediately.

Looking for more dog advice?

Find the information you need as we support you through every step of your journey with your canine companion.


Need dog insurance?

Dog insurance can help cover the cost of veterinary treatment if your dog gets injured or falls ill.


We know pets

Animal Friends Insurance is a multi-award winning FCA-regulated pet insurer, founded in 1998 to provide industry-leading pet insurance and first-class animal care to create a better life for every animal.
As one of the UK’s largest pet insurance providers, Animal Friends works with vets, veterinary professionals, and partners pioneering the latest veterinary technology & healthcare advancements to achieve our vision.
Our policyholders have helped donate over £8.5 million to more than 800 animal charities worldwide and by educating and inspiring others to act on current events and responsible pet ownership, Animal Friends is driving positive change for animal welfare and conservation.