Mast Cell Tumors in Dogs: Symptoms, Staging & What to Expect

Mast cell tumors are the most common type of malignant tumor found in dogs. They present as skin nodules on the skin. Noticing skin nodules on your dog’s skin may give you some concerns, but not to worry, in this article, you will understand what mast cell tumor looks like, its signs, stages, diagnosis and available treatment options.

Content:

1. What Is a Mast Cell Tumor in Dogs?
2. Signs & What It Looks Like
3. Staging & Grading
4. Diagnosis & Treatment Options for Canine Mast Cell Tumors
5. Prognosis: Life Expectancy & Survival Rate by Grade
6. Conclusion

What Is a Mast Cell Tumor in Dogs?

Mast cell tumors are nodular masses found under the skin of dogs. Mast cells are normal cells of the immune system which could become cancerous. When they do, they become hyperactive, release histamine and cause inflammatory reactions.

Signs & What It Looks Like

Mast cell tumor presents as nodules or masses under the skin, some reddened while some could appear like benign wart or a squishy mass under the skin.

Features of mast cell tumors on skin may include:

• Varied sizes of lump
• Reddened lump
• Sore mass
• Itching and pain
• Darier’s sign (puffy after touch)

Other systematic signs other than skin lesions may include:

• Diarrhea
• Enlarged lymph nodes, spleen and liver
• Swollen belly
• Stomach upset
• Digestive bleeding

Staging & Grading

To locate and identify the stage of a mast cell tumor, veterinarians carry out staging and grading through a series of tests such as X-rays, blood work, ultrasound and microscopic examinations.

Low vs. High Grade

Low grade mast cell tumor cells are easily differentiated, slow growing and less likely to spread.

While the high grade tumors are difficult to differentiate, they are metastatic and often ulcerative. These cell types could spread to lymph nodes and internal organs.

Stage 1–4 Explained

The different stages of mast cell tumor in dogs:

• Stage 1: Only one tumor on the skin is identified with no spread observed.
• Stage 2: One cell tumor found with possible spread to a nearby lymph node.
• Strange 3: Multiple tumor cells found on the skin with or without lymph nodes involvement.
• Stage 4: Here the tumor cells have spread to internal organs and other locations such as the liver, spleen, blood and bone marrow.

Diagnosis & Treatment Options for Canine Mast Cell Tumors

A fine-needle aspiration technique is usually used to diagnose mast cell tumors by suctioning a sample of a cell through a needle and syringe then viewed under a microscope. In my practice, local lymph nodes are examined, abdominal ultrasound done accompanied with microscopic examination of splenic and hepatic cells.

For treatment, there are varied options. A study revealed that most mast cell tumors in dogs are cured with surgery, especially low grade non-metastatic mast cell tumors.

“Surgery is considered the gold standard for mast cell tumor treatment, and it’s often curative”.
— Dr. Lauren Alfino

Aside surgery, here are effective mast cell tumor treatment options:

• Electrochemotherapy: This method uses direct application of chemotherapy into tumor cells. This method ensures there is no relapse.
• Chemotherapy: This method targets tumor cells that must have spread throughout the body. Common drugs of choice are Vinblastine and lomustine (CCNU).
• Radiation Therapy: This method employs the use of X-rays to alter and destroy cancerous mast cells.
• Targeted Therapy: Here, oral medication is prescribed especially for recurrent mast cell tumor cases.
• Intramural Injection: This method employs the use of direct liquid medication injection into tumor cells to cause death of cells.

Treatment is not just enough, post-surgical care is essential to ensure the dog recovers and the site where mast cells were removed are not infected. It is recommended to adopt the Petcube App to help monitor recovery, this will help notice changes and behaviour of the dog as it recovers from surgery.

“Mast cell tumors don’t tend to spread, they stay local, this makes surgery an effective treatment option”.
— Reddit User

Prognosis: Life Expectancy & Survival Rate by Grade

Prognosis of canine mast cell tumor depends on the grade of tumor cells found.

• Low-grade tumors: This type of tumor has an excellent prognosis. With surgical treatment, dogs tend to live out their natural lifespan with a 4-year survival rate for 83-86% of low-grade causes according to a study done.
• High-grade tumor: This type of tumor usually has a guarded prognosis because of its advanced stage.

Conclusion

Mast cell tumors in dogs could be fatal when left untreated. It is crucial to visit the vet for a check up if unusual skin nodules are found on your dog. This way they could be curtailed at an early stage. With the right treatment and early detection, dogs with mast cell tumors could be treated and still live their best lives.