What is cancer?

Cancer is the uncontrolled and abnormal growth of a subset of cells. They are able to bypass the normal cell growth controls, allowing them to grow and replicate without receiving instructions to. These cells acquire changes or mutations which can have a negative impact on the their surrounding, healthy, tissue. Not all cancers form tumours but if they do then we refer to the initial mass or tumour as the primary tumour.

What do the terms benign and malignant mean?

Tumours are referred to as being benign or malignant. Benign means the tumour is not cancerous and will therefore not spread / metastasise to other organs but may grow significantly in size and can cause local problems, such as discomfort. Malignant tumours contain cancerous cells and have the ability to spread to other organs.

What are the different types of canine cancer?

  • Lymphoma
    Lymphoma is a cancer of the white blood cells and the lymphoid tissue (such as lymph nodes). The lymphoid tissues most commonly affected are lymph nodes throughout the body, the gut, chest, liver, spleen and kidneys. It can affect any breed, sex or age
  • Mast cell tumour
    Mast cell tumours are the most common skin tumour in dogs. They can also affect other areas like the gut, spleen, liver and bone marrow.
  • Osteosarcomas
    Osteosarcomas are bone tumours, typically they are found in the dog’s limbs, but they can also occur in other bones (like spine, skull and ribcage) and rarely are also found in other tissue, such as the mammary gland.
  • Soft tissue sarcoma
    Soft tissue sarcoma are a broad group of cancers affecting connective, muscular and nervous tissue
  • Fibrosarcoma
    Fibrosarcoma is an example of a soft tissue sarcoma arising from fibrous connective tissue, often occurring in or beneath the skin. They are normally found on the limb and trunk regions but also occur around the mouth and nose.
  • Haemangiosarcoma
    This is an aggressive cancer of the blood vessel walls. They can be found anywhere, though most commonly in tissues with a rich blood supply such as the spleen, heart or liver.
  • Carcinoma
  • Squamous cell carcinoma
    Squamous cell carcinomas make up the majority of both - skin tumours and tumours in the mouth. Squamous cell carcinomas on the skin often occur on areas of light or unpigmented skin (areas like the nose, eyelids, lips or the tips of white ears) and have been linked to exposure to the sun (UV).
  • Oral squamous cell carcinomas
    These are tumours occurring inside the mouth, they can cause ulcers and may therefore cause your dog to struggle eating.
  • Anal sac adenocarcinoma
  • Melanoma
  • Leukaemia
  • Mammary Tumours
    In humans, we call this breast cancer. It is more common in female dogs, particularly older, entire dogs (dogs that have not been spayed).

What does metastasis mean?

If a cancer is referred to as metastatic, that means the cancer is no longer confined to one place in the body and is able to spread.

Is cancer in dogs like cancer in people?

Dogs can get a lot of cancers that we see in humans. Often the tumour progression can be a lot quicker due to the overall shorter life span of our pets compared to us people. The way we treat cancer in dogs is also very different and is less aggressive than in humans. The aim when treating our patients is to ensure a good quality of life and to prolong it, where possible

What is the difference between the terms stage and grade for cancer in dogs?

  • Staging describes a tumour’s size and how far the tumour has spread from the original mass (metastasis). It can often be determined by your vet using diagnostic imaging and sampling techniques.
  • Grading is usually done by a veterinary pathologist and gives information on the appearance of the cells when looked at under a microscope. There are different methods of grading tumours, but they all aim to classify how different the tumour cells are from normal, healthy cells, and aids prognostication.

Does cancer cause pain in dogs?

There are different ways cancer could cause dogs pain, for example if the tumour is enlarged and pressing on other areas of the body or if the tumour becomes ulcerated. Both your referring vet and our specialists will discuss ways to appropriately manage your pet’s pain.

Is cancer treatable in dogs and how is it treated?

The majority of cancers in dogs are treatable but only rarely is treatment curative. We aim to prolong life maintaining a good quality of life. Some patients will receive chemotherapy, surgery, radiotherapy or a combination of those treatments to achieve this. We often refer to these treatments as definitive. In very advanced cases we sometimes opt for palliative treatment making the patient comfortable and slowing down tumour progression as best as possible.

What are the side effects of cancer treatment in dogs?


Like any other surgery, there are always risks associated with undertaking surgery to remove a mass. After the surgery, it is important we monitor the patient for signs of regrowth and pain.


With most chemotherapy protocols in animals, we try to minimise the side effects, though it can be difficult to predict how each animal will react. If the chemotherapy is affecting your dog’s gastrointestinal system, you may notice vomiting, diarrhoea and/or a loss in appetite. Dogs do not typically lose their fur with chemotherapy, but the texture of their fur may change, and you may notice that they lose some whiskers.


Fur loss and changes to skin pigmentation can sometimes be seen. These are usually cosmetic changes. In some cases, reddening of the skin and ‘hot-spot-like’ areas can occur during and after radiotherapy.

What should I expect if my dog has been diagnosed with cancer?

Every case is different, and the treatments have different outcomes – some might have side effects. With chemotherapy, you will be asked to take extra precautions to not come into contact with your pet’s urine or faeces after they received treatment. Risk of significant exposure is unlikely but certain people are more at risk (those who are pregnant or breast feeding, children, people trying to conceive, immunocompromised people).

Will my insurance cover my dog’s cancer treatment?

Most insurance companies will cover the costs. We would however advise you to contact your insurer to discuss the matter and to also be certain of the maximum coverage.

How can I help my dog if it has been diagnosed with cancer?

We generally advise to treat your pet as normal and allow him or her to carry on their daily routines. Our staff would always make you aware of any precautions you should be taking with them. You may be asked to administer certain medications at home which may either be a chemotherapy drug or a supportive medication such as pain killers and prophylactic drugs such as anti-sickness medication.

Is it safe for my dog to have vaccines and flea and worming treatment when receiving medication for cancer?

Always check with your vet first, but most flea and worming treatment is safe to give when receiving medication for cancer. It is generally advised not to give vaccinations to dogs whilst receiving chemotherapy or immunosuppressive medication as vaccines rely on an immune response which these patients can fail to produce to adequate levels to be protected in later life.

Do I need to change the way I feed my dog during cancer treatment?

We generally advise against changing the diet rapidly, especially when your pet is receiving chemotherapy. These medications can sometimes cause loose faeces or even diarrhoea and vomiting and it is important for your oncologist to be able to assess this. In some dogs a diet change can have similar effects and the chemotherapy protocol may be falsely changed.

What should I do if I am struggling to manage my dog’s cancer treatment?

If at any point you are concerned about your pet receiving treatment it would be advisable to contact your vet for advice. If your pet is receiving chemotherapy you should discuss further action with your animal’s oncologist.

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