Mast Cell Tumours in Dogs

What Are canine Mast Cell Tumours?

Mast cell tumours are one of the most common type of skin tumours in dogs. They arise from mast cells, which are special types of cell which play a part in the animal’s immune system. They are primarily found in the skin and play a part in inflammatory reactions, releasing a chemical called histamine. Mast cell tumours can vary greatly in shape and appearance (which often makes diagnosis difficult) and they can be present on or under the skin (in the subcutaneous tissue). In rare cases, mast cell tumours can arise from areas other than the skin. Mast cell tumours can occur in all ages and breeds of dogs, but the average age at presentation is ~8-9 years of age. The exact cause of mast cell tumours is still uncertain.

How Do I Know If a Lump is a Mast Cell Tumour?

Examination of any skin lump which is of concern generally involves a fine needle aspirate (FNA). This involves inserting a small needle with an attached syringe into the lump and aspirating some cells. This can usually be done with the owner present in the consultation room and rarely requires sedation . The cells collected are then examined under the microscope for the presence of purple granules, which is the classical appearance of mast cells. We also examine associated lymph nodes at this stage to determine whether they appear to be affected.

How Can Mast Cell Tumours Be Treated?

Surgical Removal

Due to the invasive nature of mast cell tumours, a wide surgical margin around and deep to the tumour is taken to ensure that the entire tumour is removed; consequently, the surgical wound is usually much larger than the tumour. If the associated lymph node appears to be involved, we may also remove this at the same time. If the histopathological analysis reveals that the excision was incomplete (ie there are still tumour cells remaining in the tissue), further surgery is often required.

Injection of chemotherapy into the mast cell tumour if is small and in the skin is now commercially available and fantastic!

STELFONTA for dog Mast Cell Tumour Therapy

STELFONTA is a prescription medicine used in dogs to treat mast cell tumors on the skin or in the tissues just under the skin. Given as an injection directly into your dog's tumor, it destroys the tumor by breaking down cancer cells and starving their blood supply.

Is Stelfonta safe for dogs?
The most common side effects of Stelfonta (which may affect more than 1 in 10 dogs) are mild to moderate pain on injection, wound formation at the injection site with pain and lameness, as well as vomiting and increased heart rate.

What Is The Prognosis?

Mast cell tumour grading (usually following surgery) provides the best predictor of prognosis. Usually reasonable.

Should mast cell tumors in dogs always be removed?

Answer: Mast cell tumors (MCT) are the most common malignant tumor in dogs. Most MCTs (more than 80 percent) are of low or intermediate grade and curable with surgery alone. So, surgical removal is the treatment of choice in most cases.