Molly, the 14-year-old centre cat at Northiam

Coping with cancer in cats

As with people, cats commonly get cancer, especially as they get older – although even young cats can be affected. The commonest types of cancer affect the white blood cells, the skin and the breast.

The vet says my cat has a tumour – is it cancer?

The language surrounding cancer can be confusing and definitions are difficult. Tumours (also called growths) can be cancerous or non-cancerous, depending on what they do within the body.

A tumour is the uncontrolled growth of microscopic body components (known as cells). This causes disease, often by forming a lump within the organs of the body and disrupting their normal layout so they cannot function properly. Some tumours stay in the tissue where they started; these are generally described as a 'benign' and are not actually cancers. Others can spread within the body; these are described as 'malignant' and are called cancers.

What causes cancer? Could I have done something to prevent it?

There are some factors that statistically make certain cancers more likely to occur. White cats are more at risk of skin cancer from sunlight exposure. Infection with some viruses, including feline immunodeficiency virus (FIV) or feline leukaemia virus (FeLV) may increase the chances of getting cancer. Spaying a female cat when she is young greatly reduces the chances of breast cancer.

What are the symptoms?

Cancer can occur in any part or system of the body, so its symptoms are very varied. Many of the symptoms are also common to a large range of diseases. A diagnosis of cancer cannot be made on symptoms alone.

You should certainly take your cat to the vet if you have discovered a lump, but not all lumps are cancers. Non-healing sores should also be investigated. Other signs of tumours (benign or cancerous) affecting internal organs can include loss of appetite, weight loss, lethargy and weakness, difficulty in breathing, limping and recurrent digestive problems. However, these can be signs of many other illnesses as well. They are certainly signs that mean you need to visit the vet. Even though cancers may be slow growing, they can sometimes cause sudden signs of illness.

What happens next?

Usually, the vet cannot tell whether an animal has cancer just by looking. Blood tests to screen for cancer are still in their infancy. Further tests, such as blood samples and x-rays, are usually needed. Ultrasound or MRI scanning may be suggested. It may be useful to test whether the cat is infected with feline leukaemia virus and feline immunodeficiency virus.

The tests give an indication of your pet's general health, which affects his ability to withstand surgery. They may also help in discovering whether the cancer has spread to other areas of the body – a process that vets refer to as “staging”. A biopsy (taking a small sample for examination under a microscope) may help to identify the tumour and see if it is cancerous. Reaching a definite diagnosis can sometimes be difficult – for example, biopsies do not always contain enough good quality material for diagnosis.

Read more on FIV and FeLV.

Can cancer be treated?

There are many types of tumours and treatment is available for some non-cancerous and even for some cancerous tumours. For an isolated lump that has not spread, surgery may provide a cure, but it does depend on where the tumour is growing. Even a benign tumour in an area such as the brain cannot be easily removed in animals. Where a cancer is spreading inwards, the possibilities for treatment depend on the exact type and how far it has spread. However, quality of life is important and if an animal is in severe unrelievable pain, your vet is likely to encourage you to choose euthanasia.

There are three basic types of treatment – surgery, chemotherapy and radiotherapy. Several other new therapies are also sometimes available, such as photodynamic therapy or immunotherapy. Some forms of treatment require frequent visits to your own vet, or to specialists and it may be important for treatment to be given at particular time intervals.

Surgery is often chosen for tumours of the skin, or for internal growths that are apparently, distinct. The lump removed at surgery will usually need to be analysed to find out whether or not it is likely to have spread. Sometimes with internal growths where the size of the tumour is causing illness, surgery can relieve the symptoms but the risk of recurrence remains.

Chemotherapy is appropriate for several types of cancer. Veterinary chemotherapy usually has few side effects, or none at all, because the doses used are smaller than those used in humans. Unfortunately, it does not usually cure – the aim is to slow the cancer down and reduce the symptoms.

Chemotherapy is sometimes carried out following surgery if it has not been possible to remove the entire tumour, to try to slow down recurrence. It is also used for widespread cancers that cannot be surgically removed, such as those involving the white blood cells (leukaemias). Some types of chemotherapy may be available from your own vet; others are only carried out by specialists.

Regular visits to the vet for treatment are usually essential and sedation may be needed during treatment. You may need to give tablets as well. Possible side effects from chemotherapy include a short period of reduced appetite, vomiting or diarrhoea. Sometimes the drugs will cause the white blood cell count to drop, which can increase the likelihood of infections, so blood tests are usually taken to check for this during treatment.

Radiotherapy is only available at a few specialist centres. Again, it does not usually cure, and regular visits are often needed for a period of time. Because your pet needs to be absolutely still for the treatment, a short general anaesthetic is given for each treatment.

Is it fair to treat an animal with cancer?

Vets are well aware of the importance of keeping animals pain-free and current painkillers are very effective. Sadly, for all animals with an incurable cancer, there will eventually come a point when they are suffering and have lost their quality of life. You and your vet should work together to recognise when this occurs and then opt for euthanasia. However, most vets would agree that a healthy, happy animal does not need to be euthanised even if your cat has an incurable disease.

How long will my pet live?

This is something that cannot be predicted with certainty. The type of cancer and how far it has advanced give some idea, and for some cancers there are more specialised tests that help indicate prognosis. However, like all illnesses, cancers do not necessarily follow a set course. Unfortunately, sudden deteriorations can occur.

Specific types of tumours and cancers

The information given below is not exhaustive, but it gives some general information about types of cancer commonly found in cats.

Skin tumours

Many lumps that occur in the skin are benign and can be surgically removed. Occasionally, there may be obstacles to removal if the lump is very large, or in an area where repairing a surgical wound is difficult. This is something your veterinary surgeon will discuss. Unfortunately, there are some types that recur in the same place and a few that spread to other sites in the body. Biopsies may be helpful because if an aggressive tumour is identified, then cutting out a larger area of skin at surgery may reduce the likelihood of recurrence or spread.

Breast tumours

Cats have four breasts on each side of the tummy, visible as two rows of nipples, and tumours may occur in one or more. Four fifths of these tumours are unfortunately malignant cancers. Surgery to remove all the breast tissue on the affected side is usually recommended so that further lumps cannot grow on that side – which quite often happens if only the lump is removed. However, it is unlikely to stop the spread of cancer internally. If the growth is malignant, then spread to the lungs is common, so chest x-rays prior to surgery are advisable, although an early spread may not be visible.

Leukaemia or lymphoma

This is a cancer that affects the white blood cells. A particular type of white blood cell, called a lymphocyte, is usually involved. Lymphocytes circulate in the blood and also in the lymphatic system, which is a system of vessels and centres (swellings called lymph nodes – are often referred to as glands). This is where the body screens for infections and other foreign bodies that may be attempting to enter the system.

When lymphocytes become cancerous, their numbers increase uncontrollably. The lymphocyte numbers in the blood may rise, but often the lymphocytes sit in one place and multiply. There may be enlargement of one or more lymph nodes, producing lumps in the throat area or elsewhere, or it may involve internal organs, such as the liver, spleen or bowel. The cancerous lymphocytes can easily spread to other parts of the body through the blood circulation or the lymphatics (tubes that connect the lymph nodes). They may also multiply in one place only, particularly in the bowel.

Because lymphoma is usually widespread, surgery alone is not usually appropriate. Untreated, the average survival time from diagnosis is about two months. This can be prolonged with chemotherapy (in some cases for 12 months or occasionally longer), although unfortunately not all lymphomas respond, especially if the cat has feline leukaemia virus. Survival expectations are something you should discuss with your veterinary surgeon.

Warning signals that your pet may be in pain:

  • Changes in behaviour
  • Loss of appetite
  • Reluctance to move around and go for walks 
  • Restlessness, difficulty in getting comfortable
  • He may seem withdrawn or tense
  • Purring is not a sign that your cat is free from pain – even badly hurt cats may purr
  • An improvement in demeanour with painkillers (only ever give painkillers prescribed by a vet)

For further information, see time to say goodbye to your cat.

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— Page last updated 20/12/2023