Frequently Asked Questions about mast cell tumors

A mast cell is a type of white blood cell involved in the body's allergic response. When exposed to allergens, mast cells release chemicals like histamine, which cause common allergy symptoms such as itchiness, sneezing, and a runny nose. 

A Mast Cell Tumor (MCT) is a cancerous growth made up of mast cells, commonly forming in the skin but potentially affecting other organs like the spleen and liver. MCTs are the most common skin tumors in dogs.  

The exact cause of mast cell tumors (MCTs) in dogs is not fully understood, but several factors may contribute to their development:

• Genetics: Certain breeds, such as Boxers, Bulldogs, and Boston Terriers, are more prone to MCTs, suggesting a genetic predisposition.
• Environmental Factors: Exposure to environmental toxins or carcinogens may increase the risk of developing MCTs.
• Chronic Inflammation or Irritation: Persistent inflammation or skin irritation could potentially lead to the formation of MCTs.
• Immune System Dysregulation: An imbalance in the immune system may contribute to abnormal mast cell growth and tumor formation.

Further research is ongoing to better understand the precise causes and risk factors associated with MCTs in dogs and we want to aid in this pivotal research. 

Clinical signs of a mast cell tumor (MCT) in dogs can vary depending on the tumor's location and the extent of its spread. Common signs include:

• Skin Masses: A lump or mass on the skin, which may change in size, appear red, or become ulcerated.
• Swelling: Swelling around the tumor due to the release of histamine and other chemicals.
• Itching or Irritation: The tumor may cause the dog to scratch or lick the affected area.
• Gastrointestinal Symptoms: Vomiting, diarrhea (sometimes with blood), and loss of appetite if the tumor affects internal organs or releases large amounts of histamine.
• Systemic Symptoms: Lethargy, weight loss, or difficulty breathing if the cancer has metastasized to other parts of the body.

Early detection and diagnosis are crucial for managing MCTs effectively. If you notice any unusual lumps or changes in your dog's health, please consult your veterinarian. 

MCTs in dogs are diagnosed through a combination of the following methods:

• Physical Examination: A veterinarian will inspect the lump or mass on the dog’s body and assess any changes in size, shape, or texture.
• Fine Needle Aspiration (FNA): A small sample of cells is taken from the tumor using a fine needle and examined under a microscope. This is often the first diagnostic step and can help identify the presence of mast cells.
• Biopsy: A tissue sample from the tumor is surgically removed and sent to a laboratory for a more detailed analysis. This helps confirm the diagnosis and provides information on the tumor's grade and aggressiveness.
• Histopathology: The biopsy sample is examined to determine the malignancy of the tumor and its potential to spread.
• Imaging Tests: X-rays, ultrasound, or CT scans may be used to check for the spread of the tumor to other organs.
• Blood Tests: These may be conducted to assess the overall health of the dog and to detect any signs of systemic effects from the tumor.

Diagnosing MCTs accurately is essential for determining the appropriate treatment plan and prognosis.

Treatment options depend on the tumor's size, location, grade, and whether it has spread. Your veterinarian should determine the best treatment for your dog. 

Common treatments include:

• Surgery: Surgical removal of the tumor is the primary treatment, especially for localized MCTs. The goal is to remove the tumor with clear margins to reduce the risk of recurrence.
• Radiation Therapy: This may be recommended if complete surgical removal isn't possible or if the tumor is in a location that makes surgery difficult. It can help control the growth of the tumor and prevent recurrence.
• Chemotherapy: Used for high-grade or metastatic MCTs, chemotherapy can help manage the spread of cancer and improve the dog's quality of life. It is often used in combination with surgery or when surgery isn't an option.
• Targeted Therapy: Medications like tyrosine kinase inhibitors such as Palladia®  (toceranib) can specifically target cancer cells and are used for non-resectable or metastatic MCTs. STELFONTA® (tigilanol tiglate injection) is an intra-tumoral injection approved for use in nonmetastatic MCTs and is used in specific areas. 
• Supportive Care: Antihistamines (e.g., Benadryl) and corticosteroids may be prescribed to manage symptoms caused by histamine release, such as swelling and gastrointestinal issues.
• Combination Therapy: A combination of the above treatments may be used depending on the specific case and the veterinarian's assessment.
• Holistic Care: Many owners are finding a more holistic approach beneficial.  While holistic care can be a beneficial complementary approach, it is essential to coordinate with a veterinarian, especially one experienced in integrative medicine, to ensure that these treatments do not interfere with conventional treatments like surgery, chemotherapy, or radiation therapy. If you're interested in exploring holistic care, there is a group on Facebook that might be beneficial to join:  Holistic Help for Dogs with Mast Cell Cancer - Cleo’s Protocol. 

Early detection and a tailored treatment plan are crucial for improving outcomes. Regular follow-ups and monitoring are also important for managing the condition. The approaches mentioned above are for examples only, please consult your veterinarian for the best treatment for your dog. 

To hear what other pet parents are doing or get support, consider joining  Pet Parents of Mast Cell Tumor Dogs