What is cancer?

Cancer is the uncontrolled and abnormal growth of a set of cells. They can bypass the normal cell growth controls, allowing them to grow and replicate without receiving instructions to. They can acquire changes or mutations which can have a negative impact on the surrounding, healthy, tissue. Not all cancers form tumours / masses 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 unlikely to be cancerous and will therefore not metastasise (spread) to other organs; the tumour however can significantly grow in size locally. Malignant tumours contain cancerous cells and are known to metastasise.

What types of cancer are there?

  • Lymphoma
    Lymphoma is a cancer of the white blood cells and the lymphoid tissue (such as lymph nodes). The lymphoid tissue most commonly affected is found in the gut, structures in the chest, liver, spleen and kidneys. Cats who have contracted Feline Leukaemia Virus or Feline Immunodeficiency Virus are more likely to develop lymphoma. It can affect cats of any breed, sex or age. Feline Leukaemia Virus is a virus, which amongst other things, causes lymphoma as well as lymphatic leukaemia. There is a vaccine against FeLV which is used to prevent disease and protect the cat population.
  • Squamous cell carcinoma
    Squamous cell carcinomas make up the majority of feline skin and mouth tumours. 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 has been linked to exposure to the sun (UV light). Oral squamous cell carcinomas (tumours occurring in the mouth) can cause ulcers and your cat may struggle with eating.
  • Mast cell tumours
    Like squamous cell carcinomas, these can occur on the skin. There are two main types of mast cell tumours in cats:
    • mast cell type (often found in cats over four years old) and
    • histiocytic type (more commonly seen in Siamese cats under four years old).
  • Feline Injection Site Sarcoma
    These are rapidly progressive and aggressive tumours which have been associated with injection sites. They can grow quickly but often respond well to surgery. Surgeries can be extensive in order to catch all of the disease and expert advise as well as an experienced surgeon are usually required. The first surgical intervention is extremely important for prognosis of these cats.
  • Feline Mammary Tumours
    In humans, we call this breast cancer. It is more common in female cats, particularly older, entire cats (cats 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 cats like cancer in people?

Whilst cats can get a lot of cancers that we see in humans, the way we treat cancer in cats is less aggressive than in humans. The aim in our patients is to prolong life and ensure a good quality of life rather than aiming for a curative intent treatment causing significant side effects.

What is the difference between stage and grade?

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 therefore gives us important information about potential prognosis for a patient.

Does cancer cause pain in cats?

There are different ways cancer could cause cats pain, for example if the tumour is enlarged and pressing on other areas of the body or if the tumour becomes ulcerated which might occur with squamous cell carcinomas. Both your referring vet and our specialists will discuss ways to appropriately manage the pain.

Is cancer treatable in cats and how is it treated?

The majority of cancers in cats 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 for cats?


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 tumour 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 cat’s gastrointestinal system, you may notice vomiting, diarrhoea and/or a loss in appetite. Cats 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. In case of more severe side effects we will discuss appropriate dose reductions or change of the protocol given.


Fur loss and changes to skin pigmentation can sometimes be seen in cats being treated with radiotherapy. These are usually cosmetic changes. In some cases, reddening of the skin and ‘hot-spot-like’ areas can occur during and after radiotherapy. Overall, cats are incredible in tolerating this treatment form and only rarely have more serious problems.

What should I expect if my cat 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 cat’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 cat 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 cat 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 cat?

We generally advise against changing your cat’s 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 cats a diet change can have similar effects and the chemotherapy protocol may be falsely changed.

What should I do if I am struggling?

If at any point you are concerned about your cat receiving cancer, please contact your vet for advice. If your pet is receiving chemotherapy you should discuss further action you’re your animal’s oncologist.

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