Mast Cell Tumors in Dogs

Mast cell tumors (MCTs) are the most common skin tumor in dogs, accounting for roughly 20% of all reported skin tumors. While common in dogs, they are uncommon in people. These tumors form from mast cells, which are cells that are part of the immune system in both humans and dogs. When a person gets a cold, their healthy mast cells release granules to fight the infection, with the side effect of cold symptoms like a running nose or other inflammation.

In MCTs, mutations in a certain part of the tumor cell, called the c-kit tyrosine kinase receptor, are present in roughly 33% or more of these tumors. Because we know that this part of the cell isn't functioning correctly, and there are drugs that address this type of dysfunction and others, MCTs are a good candidate for targeted therapy

Veterinary oncologists often use targeted therapy to treat MCTs, and it has shown to be effective. 

FidoCure can help create a personalized treatment approach for dogs with MCTs.

Risk Factors and Causes of MCTs

Causes: While the causes of MCTs are mostly unknown, dogs of certain breeds develop MCTs in higher numbers, which supports an underlying genetic predisposition for the disease in those breeds. 

Breed: Breeds that are predisposed to MCTs include golden retrievers, Labrador retrievers, Boston terriers, boxers, and pugs. Other breeds can also be affected by MCTs, as it is still a common diagnosis across a variety of canines. 

Age: MCTs can affect dogs of any age, but the cancer typically affects middle-aged to older dogs. However, when younger dogs do get tumors, MCTs are a common tumor type for them as well.

Disease Progression, Diagnosis, and Treatment

MCTs have extremely variable behavior: they range from relatively benign and curable when removed locally, to aggressive, rapidly metastatic, and fatal. 

The rate of tumor growth is an important factor in diagnosis — some dogs may have rapid tumor growth while others may have a tumor that has remained unchanged for months to years. Pet parents might report seeing the tumor grow and shrink repeatedly, from local inflammation that leads to intermittent swelling. Other symptoms like vomiting, lack of appetite and changes in stools might occur as the disease progresses. 

Treatment is based on the severity of the disease, and in most cases begins with the surgical removal of the tumor(s). Additional therapy should be considered for MCTs, especially those with negative factors like: spreading and growing rapidly, tumors in certain locations or that extend deep into the body, additional symptoms like vomiting, and spread to the lymph nodes. 

When weighing therapy options, the unpredictability of the disease is important to understand. Some patients begin with a seemingly more benign version of MCTs and develop a systemic, aggressive disease; others with more negative initial diagnoses sometimes still achieve long term recoveries. 

To diagnose MCTs, a veterinarian will perform a physical examination and a biopsy, or small sample of tumor cells, sent to a lab for confirmation that those cells are indeed MCT cells. In addition to a biopsy, the FidoCure diagnostic test is also an option for testing the genetic signature of the tumor and understanding additional treatment options.

Learn more about the FidoCure process and how it can aid in the treatment of MCTs.

FidoCure + Mast Cell Tumors

While this disease can be highly variable, and seemingly unpredictable, FidoCure has proven effective in evaluating and treating MCTs. One FidoCure patient, Lulu, was able to take more control in her battle against MCTs with the help of FidoCure

Lulu's Journey

"We were devastated when Lulu was diagnosed with an aggressive mast cell tumor just before she turned 6 years old. Committed to doing everything we could for her, we were all in on surgery, radiation and chemo. Six months after her last chemo treatment, we found another tumor. And then another. And another. Four surgeries later, Lulu was growing more tumors before her surgery wounds were even healed. Lulu’s oncologist Dr. Brooke Fowler suggested FidoCure. Almost  immediately, Lulu’s tumors shrunk and soon disappeared. We wished we had known about FidoCure two years ago so we could have spared Lulu all the pain and discomfort and ourselves all the stress and despair.  Every day we have with Lulu from now on is a gift and we feel so fortunate that she is thriving and happy again. Thank you FidoCure!"

Dana Scanlan, Boulder, CO

DISCLAIMER: FidoCure™ is a leader in oncology research for dogs, and our team is committed to the breakthroughs in cancer biology to evolve canine cancer care, with each patient improving the outcomes for all future canine cancer patients. We use our best efforts to inform the veterinarian, who then decides which option is best for their patient. The therapies that veterinarians may prescribe and order from compounding pharmacies after receiving genetic test results from FidoCure, may constitute extra-label uses of those drugs. FidoCure is continuing to gather research data in support of novel oncology therapeutics in dogs.

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