Mast cells are normally found throughout the body and are often involved in functions such as inflammatory and allergic reactions. Mast cell tumours (MCT) are the cancerous proliferation of mast cells at a particular site/s of the body. At present, no one knows exactly what causes normal mast cells to transform and develop into malignant tumours.
MCTs are one of the three most common types of skin cancer in dogs, and is also a common type of skin cancer seen in cats, although at a lower frequency than dogs1.
Although MCTs are usually associated with the skin, they can also occasionally develop in the internal organs, such as in the gastrointestinal tract or the spleen. Depending on the location, MCTs that develop in non-skin regions are termed disseminated or systemic mastocytosis or mast cell leukaemia.
While any dog or cat has the potential to develop MCTs, some of the following canine and feline breeds are thought to be more susceptible to developing these tumours. Do note that this is not an exhaustive list:
It is not possible to diagnose a MCT simply by just its appearance, because it can resemble many other benign or cancerous skin lumps.
A MCT on the skin may also present in many different ways. It may appear as a firm or soft lump attached to or located just beneath the skin. The mass may fluctuate in size and show signs of redness, swelling, bruising, hair loss and/or ulceration, or the skin overlying the tumour may just appear normal. Affected pets may have a single tumour or several masses in different locations on the body.
The non-skin (visceral) form of MCTs that occurs on internal organs may present in different and often vague ways, with affected pets showing a variety of vague clinical signs, for example loss of appetite, lethargy, vomiting, diarrhoea, abdominal enlargement or difficulty breathing.
Your veterinarian may recommend a number of tests to help determine if a mass is a mast cell tumour. These tests may also help to stage aggressiveness of the MCT. Staging is the process of determining the extent of metastasis (tumour spread) throughout the body.
While these may seem like a long list of diagnostic tests, not all patients with MCT will be subjected to the full range of tests as every patient is different. Your veterinarian will be able to tailor a diagnostic plan specifically for your pet.
Depending on whether the MCT is limited to the skin or if other organs are involved, treatment may include but are not limited to1:
The outcome and survival rate of pets with mast cell tumours depends on many factors. If there is one tumour that is limited to the skin, is a low grade MCT with no evidence of metastasis, and is completely excised at time of surgery, then the prognosis can be very good.
For more aggressive MCTs, systemic mastocytosis or those with suspicious evidence of spread to elsewhere to the body, the prognosis may not be as good. Your veterinarian may recommend a referral to a specialist oncologist for guidance about all available treatment options.
As early diagnosis and treatment can vastly improve the prognosis, it is important that you have your veterinarian to examine and/or investigate any new lumps or bumps, or changes to existing masses on your fur friend.
Please do not hestitate to contact us at (06) 3588675 if you have any concerns about suspicious lumps and bumps on your pet's body.