Is This Lump Normal? A Guide to Identifying Mast Cell Tumors in Pets
Stephanie and Bogie
By Stephanie Boldt, RVT
My beloved dog Bogie developed strange, pink, fleshy growths about 10 years ago. At the time, he also seemed a little off and was vomiting. As a registered veterinary technician starting my career, I knew the importance of checking any unusual lumps.
The veterinarian examined Bogie and administered an injection of Benadryl to prepare for a fine needle aspirate. This minimally invasive procedure involves taking a small needle and inserting it into the lump to collect cells for examination under a microscope. After what felt like forever, the veterinarian confirmed Bogie had mast cell cancer. I was devastated, but I learned valuable information about this disease that I now want to share with you.
What Are Mast Cell Tumors?
Mast cell tumors (MCTs) are cancerous growths that originate from mast cells and account for 15% to 20% of skin cancers in dogs. Mast cells are typically found in the skin and help fight inflammation and allergic reactions by producing histamines. However, when these cells cluster abnormally, they form tumors.
MCTs vary in severity, with stage III being the most aggressive. Disturbing these tumors can release toxic granules, spreading cancer further in the body. This is why Benadryl, an antihistamine, is often administered to suppress this reaction during diagnostic procedures like needle aspirates.
Diagnosing Mast Cell Tumors
After Bogie’s diagnosis, the staging process began. This involved:
Chest radiographs to check for lung involvement.
Bloodwork to assess overall health.
Abdominal ultrasound to detect any spread to the abdomen.
Fortunately, Bogie’s disease was localized to his lumps. The veterinarian arranged for a surgeon to remove the tumors, which were in awkward areas like his armpit and chest. The surgery was successful, and clear margins—no cancer detected in the surrounding tissues—were achieved. The tumors were classified as low-grade, meaning low malignancy. Bogie was cancer-free for a time!
Treatment Options for Mast Cell Tumors
Treatment for mast cell tumors includes:
Surgery – Often the first recommendation to remove the tumor.
Radiation and Chemotherapy – Additional treatments for more aggressive or widespread cases.
Stelfonta – A newer option that involves injecting a drug into the tumor to cause necrosis. While effective, it carries risks and should be thoroughly discussed with your veterinarian.
The Importance of Diligence
Mast cell disease affects the skin and intestinal tract, and even with clear diagnostic tests, it’s impossible to detect every cancerous cell. Regular monitoring is crucial. Any new, unusual, or growing lumps—or lumps that change size—should be checked by a veterinarian immediately.
Over the past 14 years, Bogie has undergone four surgeries for mast cell tumors. Thankfully, all were low-grade. I credit this to being vigilant about checking and addressing any new lumps promptly. Regular examinations and early intervention can make a significant difference.
What About Cats?
While this article focuses on dogs, cats can also develop mast cell tumors. If you have concerns about your pet, consult your veterinarian for advice tailored to their specific needs.
Conclusion
Lumps on your pet can be concerning, but not all are harmful. Stay proactive about your pet’s health, and don’t hesitate to consult your veterinary team if you notice anything unusual. Early detection and treatment can save lives!