Mast cell tumours in cats

If your cat has been diagnosed with a mast cell tumour, knowing more about the disease can help you provide them with a better quality of life.

Mast cell tumours in cats represent 20% of skin tumours and 15% of splenic tumours. They are the third most common intestinal tumour.

What is a mast cell tumour?

Mast cells are part of the body’s immune system. A mast cell tumour is an abnormal growth of mast cells and can be found in a cat’s skin, spleen, or intestines. 

The tumour contains histamine granules that, when released, can cause gastrointestinal signs, or allergic reactions. A mast cell tumour can be “well-differentiated”, which represents between 50% and 90% of all cases in cats, or “poorly-differentiated”, and have the potential to spread to other body organs (metastasis).

What are common mast cell tumour signs in cats?

Early signs include:

  • A skin tumour, possibly pink or red in color
  • Itching at the tumour
  • Sudden tumour growth or disappearance

Intermediate or advanced signs include:

  • Multiple skin tumours
  • Lethargy
  • Loss of appetite
  • Vomiting or diarrhoea
  • Distended abdomen
  • Collapse

Lethargy can be a sign of mast cell tumour in cats.

How are mast cell tumours managed in cats?

Complete surgical excision of a mast cell tumour is the preferred treatment. Removal of the spleen (splenectomy) is recommended for splenic tumours. Radiation therapy and/or chemotherapy may be recommended, especially if surgery is not an option. 

Corticosteroids can lead to a brief remission. Palliative medications to prevent systemic or gastrointestinal effects can be helpful. Discussing a personalised management plan with your veterinarian and a veterinary oncologist is important for the best outcome for your cat. 

What is the prognosis for cats?

The prognosis depends on successful surgical tumour removal, and whether signs of metastasis are seen. Complete excision of a well-differentiated skin mast cell tumours is often curative, but has a 24% local recurrence rate. 

A splenic mast cell tumour has a metastatic rate of up to 22%, with a 12-19-month survival time after surgery. Intestinal mast cell tumours have a high metastatic rate and a poorer prognosis.

Management tips for a cat with mast cell tumours

At-home needs include:

  • Easy access to food, water, and litter box, and a comfortable location
  • Consistency with prescribed medications
  • Close monitoring for tumour recurrence, or systemic disease signs
  • Post-surgical care as recommended by your vet

For end-of-life care:

In a crisis:

Immediately contact your vet if your cat develops swelling or drainage at the surgery site, lethargy, loss of appetite, vomiting, or diarrhoea; collapses or vocalises in pain.

It is vital to begin end-of-life care discussions before your cat’s condition becomes unmanageable, or they begin losing their quality of life. 

The team at Goodbye Good Boy offers individualised support to help you and your family navigate this difficult time by providing quality-of-life checks, in-home euthanasia, cremation and aftercare services, and personalised memorialisation options. Our services can even be pre-paid to help ease the financial burden at the time of your pet’s passing. 

To learn more about our pet end-of-life services, give us a call on 1800 953 619 or visit our website

This article was reproduced with permission from Goodbye Good Boy advisor Dr Dani McVety, of Lap Of Love.