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Mast Cell Tumour

Although Mast Cell Tumours (MCT’s) are a common tumour affecting both dogs and cats, they behave very differently depending on which species is affected. 

What is a Mast Cell Tumour?

Mast cell tumours are tumours arise from cells called mast cells that are found in connective tissues in the body, particularly in skin and blood vessels. They have a role in the immune system. In dogs, mast cell tumours commonly occur as tumours on or under the skin. In cats, there are two forms of mast cell tumours – visceral (within the abdominal cavity), and cutaneous (on the skin).


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Which pets are most affected?

Any breed of dog or cat can have a mast cell tumour, however Boxers and other brachycephalic (short snouted) dogs tend to be overrepresented. In cats there is less of a breed predilection.  

According to PetSure data in 2020, mast cell tumours are most prevalent in the following breeds of dogs:







Bernese Mountain Dog


Dogue De Bordeaux


American Bulldog


Rhodesian Ridgeback 


Bull Arab




Staffordshire Bull Terrier


Great Dane


According to PetSure data in 2020, mast cell tumours are most prevalent in the following breeds of cats:





Maine Coon






Devon Rex


British Shorthair


Domestic Shorthair


Russian Blue






Prevalence = Total number of unique claiming pets / total number of insured pets across 12-month period. Excludes breeds with less than 500 active pet insurance policies.

Signs of Mast Cell Tumour

The signs of mast cell tumour vary depending on the location of the tumour and the species affected.  In dogs, the first sign may be a mass or lump on or under the skin. Sometimes, the cancer has progressed by the time it has been noticed, so signs may be more generalised and include vomiting, weight loss and lethargy. In cats, mast cell tumour can also appear as lumps on the skin, which are often pink and raised. In the visceral form of mast cell tumour in cats, the signs may include vomiting, diarrhoea or reluctance to eat. 

Diagnosing Mast Cell Tumour

Mast cell tumours in both dogs and cats are diagnosed by taking some of the cells from mass and studying it under a microscope. This may be done with a fine needle aspirate or a biopsy. Testing nearby lymph nodes and checking the chest for cancer spread (metastasis) with an X-ray is common. Understanding whether the cancer has spread, and how aggressive it is will help your vet devise the best treatment plan as well as give you a better understanding of prognosis. 

Management of Mast Cell Tumour 

Surgery is often recommended to remove the tumour. Radiation and chemotherapy may also be recommended by your vet. In advanced cases palliative care may be recommended. For cats, the skin tumours tend to be less aggressive than in dogs and sometimes removal of the mass can resolve the problem. 

Radiation therapy may be performed where surgery isn’t possible, or the tumour wasn’t completely removed during surgery and further control is needed. Once diagnosed with MCTs, there is an increased likelihood of others developing, so pet parents should routinely check dogs and visit their vet for diagnosis if new tumours are found.

Your Vet will be able to recommend a plan to manage your pet’s Mast Cell Tumour. 

If you are concerned that your pet might be unwell, get in touch with your vet for advice.

How much does it cost to treat?

According to PetSure claims data in the 2020 calendar year, the average, single treatment cost relating to Mast Cell Tumours was $646 with the highest, single treatment cost being $13,689.

Disclaimer: Reimbursement for these claims would be subject to limits, such as annual benefit limits or sub-limits, benefit percentage, applicable waiting periods and any applicable excess. Cover is subject to the policy terms and conditions. You should consider the relevant Product Disclosure Statement or policy wording available from the relevant provider.

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Kylie Mitchell is a veterinarian with over 17 years experience in animal health and welfare, including in the veterinary and pet insurance industries

She has three rescue cats (Noah, Bei Bei and Meeka), four very old cockatiels and a pond-full of fish.

Kylie's pets

Bei Bei
Bei Bei