If you have a cat who has been diagnosed with a form of cancer, then you may want to know all the available options for treating them. Radiotherapy is commonly used to treat human cancers – but is it an option for our cats?

What is radiotherapy?

Radiotherapy is a medical treatment that involves firing a beam of radiation (usually one similar to x-rays) at a particular part of the body. This is usually done to treat certain kinds of solid cancers; though occasionally it is used to treat other conditions, too. 

The radiation damages the cells in the cancer, causing them to die. This means that the tumour will shrink down over time, though it may not go away completely.  

Is radiotherapy available for cats?

Yes! Most veterinary hospitals which offer radiotherapy services will treat cats as well as dogs. In fact, because they are so rare, many radiotherapy services will treat a wide range of patients, including large animals and exotic species. 

However, radiotherapy is not something that is offered by local vet practices. It requires specialized training and equipment to perform. So it is only offered in larger referral centres which treat patients from a wide area. Not all referral centres will have radiotherapy facilities, so if your pet needs this kind of treatment, then you may need to travel further than usual to find it. 

What conditions can radiotherapy be used to treat in cats? 

Most of the illnesses that benefit from treatment with radiotherapy are different forms of cancer. These include:

  • Cancers of the nose, including squamous cell carcinomas and lymphomas
  • Meningioma (a type of brain tumour)
  • Soft tissue sarcomas (cancers of muscle and connective tissue)
  • Osteosarcomas (cancers of the bone)

Not all cats with these kinds of tumours will benefit from radiotherapy. Sometimes it may not be suitable, or other kinds of treatment may be better. 

Radiotherapy should not be confused with radioiodine therapy, which is used to treat hyperthyroidism and sometimes thyroid tumours in cats. This involves an injection of a radioactive substance (iodine-131) rather than treatment with a beam of radiation. 

What are the risks of radiotherapy in cats?

As with any medical treatment, there are some risks involved in radiotherapy. These include:


Cats must be under general anaesthetic to receive radiotherapy, as they have to lie perfectly still during the procedure. Generally, radiotherapy is given as a course of treatments. So it is likely that cats will need to have multiple short anaesthetics over the course, which could last days or weeks. There will usually be specialist anaesthetists at the hospital who will monitor cats whilst they are being treated; but there are still risks involved. Your cat may need to have a heart scan (echocardiogram) or other tests done before undergoing these anaesthetics. 

Early Radiation Risks

The possible side-effects of radiotherapy are classed into two categories; “early” effects, which can happen shortly after the treatment, and “late” effects, which can happen months or even years later. Radiation side-effects involve damage to cells in normal body tissues in the area that is being treated. 

With early radiation side-effects, the cells that are affected are those that are growing quickly, such as the skin or the cells that line the inside of a body cavity. 

For example, if a cat’s leg was being treated, then we could see damage to the skin, which could become red and sore, a bit like sunburn. If a cat was being treated for a nasal tumour, then we could see damage to the cells that line the inside of the nose, which could cause the cat to become irritated, sneeze, rub at the area or even have a nosebleed.

These side effects can be irritating or even painful, but there are treatments available to help ease the symptoms, and they will normally resolve over time. However, there may be some long-term cosmetic changes in the area, such as fur loss or a change in the colour of the fur. 

Late Radiation Risk

Late side-effects of radiation treatment involve damage to slow-growing cells, such as those in the brain, spine, eyes, heart, or bones.  

For example, bones in the treated area may become weaker and break more easily. Cataracts may form if a cat’s eye was near the area being treated – for example, with tumours of the nose. In very rare cases, new cancers may form in the treated area as a result of the radiation. 

These kinds of side effects will not usually get better by themselves and may need treatment from your specialist vet. 

How can I access radiotherapy treatment for my cat?

If you or your vet think that your cat may have a tumour that could benefit from treatment with radiotherapy, you can be referred to a specialist to discuss it further. They can talk you through the benefits and risks of using radiotherapy to treat your cat and come up with a personalised treatment plan. 

Radiotherapy is a good treatment option for some cats’ cancers, but it can only be done at certain specialist centres. Cats must go under anaesthetic each time they receive a dose of radiotherapy treatment, and there are some short-term and long-term risks involved with the radiation that is used. However, these treatments can be very effective in some cases. 

If you want to know whether radiotherapy is a good choice for your cat, speak to your regular vet for advice.  

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