Mast cell tumours in dogs

Mast cells are part of the body’s immune system, and can be found in the skin, lungs, and intestinal tract. They are an abnormal growth of mast cells, found most commonly in dogs in the skin. A mast cell tumour contains histamine granules that when released, can cause gastrointestinal signs or allergic reactions. 

Mast cell tumours are staged as “low-grade” or “intermediate- to high-grade”, according to the degree of malignancy and risk of spread (metastasis) to other organs. Certain breeds are predisposed to developing mast cell tumours. 

A mast cell tumour can mimic benign growths on or under the skin.

What are common mast cell tumour signs in dogs?

Early signs include:

  • A skin tumour, possibly pink or red in color
  • Rapid tumour growth or disappearance

Intermediate to advanced signs include: 

  • Multiple tumours
  • Tumour rupture
  • Enlarged lymph nodes
  • Lethargy
  • Loss of appetite
  • Vomiting or diarrhea
  • Distended abdomen
  • Collapse

How are mast cell tumours managed in dogs?  

Complete surgical excision of a mast cell tumour is the preferred treatment. Depending on the tumour grade or metastasis signs, management can include radiation therapy and/or chemotherapy. 

Corticosteroids can lead to a brief remission. Palliative medications may be recommended, to prevent systemic or gastrointestinal effects. Discussing a personalised management plan with your vet and a veterinary oncologist is important for the best outcome for your dog. 

What is the prognosis for dogs with a mast cell tumour?

The prognosis depends on successful surgical tumour removal, and the malignancy grade. Complete excision of a low-grade tumour is often curative. Dogs with higher-grade tumours, internal tumours, metastasis, or tumours that recur quickly have a poorer prognosis.  

Management tips for dogs with a mast cell tumour

At-home needs include:

  • Easy access to food and water, 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 dog develops excessive swelling or drainage at the surgery site, new tumours, lethargy, loss of appetite, vomiting, or diarrhea; or they collapse or vocalise in pain. 

It is vital to begin end-of-life care discussions before your dog‘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.