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Mast cell tumors in dogs

Mast cell tumors in dogs

In this article we’re going to be shedding light on one of the most common and perplexing health concerns that can affect our beloved canine companions: mast cell tumors (MCTs). Dogs bring immeasurable joy and love into our lives, so it's only natural that we want to ensure their well-being and provide them with the best possible care.

Mast cell tumors are a type of cancerous growth that arise from mast cells, which are normal cells found in various tissues throughout a dog's body. While MCTs can occur in dogs of any breed, size, or age, certain breeds may have a higher predisposition. This enigmatic condition can present itself as skin masses or affect internal organs, making early detection and understanding of MCTs crucial for effective management and treatment.

The veterinarian doctor treating, checking on dog at vet clinic The veterinarian doctor treating, checking on dog at vet clinic. dog vet stock pictures, royalty-free photos & images

What are mast cell tumors?

Mast cell tumors (MCTs) in dogs are cancerous growths that originate from mast cells. Mast cells are normal cells found in various tissues throughout the body, including the skin, respiratory system, digestive system, and more. They play a role in the body's immune response and the regulation of allergic reactions.

When mast cells undergo abnormal changes and start dividing and growing uncontrollably, they form a tumor known as a mast cell tumor. MCTs can occur in dogs of all breeds, ages, and sizes, but certain breeds may be more predisposed to developing these tumors.

Mast cell tumors can appear as lumps or masses on or just beneath the skin, but they can also be found in other areas of the body, including the spleen, liver, gastrointestinal tract, and bone marrow. The tumors can vary in size, texture, and appearance. Some may be small, round, and firm, while others can be larger, irregularly shaped, or ulcerated.

MCTs are classified into different grades based on their microscopic appearance and the degree of aggressiveness. The grades range from low (Grade I) to intermediate (Grade II) to high (Grade III). This grading system helps determine the tumor's behavior, potential for metastasis (spreading to other parts of the body), and prognosis.

What causes mast cell tumors?

The exact cause of mast cell tumors in dogs is not fully understood. Genetic factors, environmental factors, and chronic inflammation are believed to play a role in their development. However, the exact triggers or underlying mechanisms that lead to the formation of MCTs are still under investigation.

Early detection and prompt treatment of mast cell tumors are crucial for a better prognosis. If you notice any new lumps, bumps, or skin changes on your dog, it is important to have them evaluated by a veterinarian. The veterinarian will perform a physical examination and may recommend further diagnostic tests, such as fine-needle aspiration or biopsy, to confirm the presence of a mast cell tumor and determine its grade.

The incidence of MCTs in dogs

The incidence of mast cell tumors (MCTs) in dogs can vary depending on several factors, including breed, age, and other individual characteristics. MCTs are considered one of the most common forms of skin tumors in dogs.

Estimating an exact percentage of dogs affected by MCTs is challenging, as it depends on various factors and can vary across different populations and regions. However, studies have reported that MCTs account for approximately 16% to 21% of all skin tumors in dogs.

Additionally, the likelihood of developing MCTs may increase with age, with older dogs being more commonly affected. However, MCTs can occur in dogs of all ages, from young puppies to senior dogs.

Dog breeds that are predisposed to MCTs

While mast cell tumors (MCTs) can occur in dogs of any breed, certain breeds have been found to have a higher predisposition to developing these tumors. It's important to note that breed predisposition does not guarantee that an individual dog will develop MCTs, but it indicates a higher likelihood compared to other breeds. Here are some dog breeds that have been reported to have an increased risk of developing mast cell tumors:

It's worth mentioning that this list is not exhaustive, and other breeds may also have an increased predisposition to MCTs. Additionally, while these breeds may be more commonly associated with MCTs, dogs of any breed or mixed breeds can develop these tumors.

If you have a dog from a breed that is known to be predisposed to MCTs or have concerns about your dog's health, regular veterinary check-ups and routine skin examinations are recommended. This can aid in early detection, as early diagnosis and treatment often lead to better outcomes.

Symptoms of MCTs in dogs

The symptoms of mast cell tumors (MCTs) in dogs can vary depending on the location, size, and grade of the tumor. Here are some common symptoms associated with MCTs:

Skin Lumps or Masses

MCTs often appear as raised skin lumps or masses. They can range in size from small nodules to larger tumors. The lumps may feel firm or soft and can be found anywhere on the body, including the limbs, trunk, head, or tail.

Changes in Skin

The area around the MCT may exhibit changes in color, texture, or thickness. The skin may appear reddened, inflamed, or ulcerated. Hair loss or thinning of fur over the tumor site can also occur.

Itching and Irritation

MCTs can cause intense itching, leading to the dog scratching, licking, or biting the affected area excessively. Persistent licking or biting of a particular spot should raise suspicion for an underlying MCT.

Gastrointestinal Symptoms

In some cases, MCTs can develop internally, affecting the gastrointestinal tract. Dogs may experience symptoms such as vomiting, diarrhea, loss of appetite, weight loss, or abdominal pain.

Systemic Signs

Advanced or high-grade MCTs may cause systemic signs, indicating the tumor's potential to spread (metastasize) to other parts of the body. These signs can include lethargy, weakness, loss of energy, enlarged lymph nodes, and difficulty breathing.

It's important to remember that not all skin lumps or masses are MCTs, as there are various other benign and malignant tumors that can present with similar symptoms. Only a veterinarian can provide an accurate diagnosis through physical examination, aspiration, biopsy, or other diagnostic tests.

Woman checking dog's skin for ticks on blurred background, closeup Woman checking dog's skin for ticks on blurred background, closeup dog skin  stock pictures, royalty-free photos & images

Treatment of MCTs

The treatment of mast cell tumors (MCTs) in dogs depends on several factors, including the grade of the tumor, its location, stage, and the overall health of the dog. The primary treatment goal is to remove the tumor with clean surgical margins while considering the potential for metastasis (spread) and any concurrent health conditions. Here are the common treatment options for MCTs in dogs:


Surgical removal is often the initial treatment for MCTs. The surgeon aims to remove the tumor with sufficient margins of healthy tissue to reduce the risk of recurrence. The extent of surgery depends on the tumor's location, size, and grade. In some cases, reconstructive procedures may be necessary, especially if a large tumor requires extensive tissue removal.

Radiation Therapy

Radiation therapy may be recommended for MCTs with aggressive features, incomplete surgical removal, or if there is a high risk of local recurrence. It involves targeting the tumor site with high-energy radiation to destroy cancer cells and prevent their regrowth.


Chemotherapy may be used as an adjuvant treatment to surgery and radiation therapy. It is particularly considered for MCTs that have metastasized or are at high risk of spreading. Chemotherapy drugs can be administered orally, topically, or intravenously to target cancer cells throughout the body.

Targeted Therapies

In recent years, targeted therapies have emerged as an option for certain cases of MCTs. These therapies work by specifically targeting and inhibiting specific molecules or pathways involved in the growth and progression of MCTs. They can be used alone or in combination with other treatments.

The choice of treatment and the specific protocols used will be determined by a veterinary oncologist or veterinarian experienced in oncology. They will consider the individual dog's health, the tumor's characteristics, and the available resources to develop a tailored treatment plan.

It's important to note that MCTs can be unpredictable, and close monitoring is necessary following treatment. Regular follow-up examinations, imaging studies, and laboratory tests may be recommended to detect any recurrence or new tumor growth.

Doctor embrace of scared dog with love Doctor embrace of scared dog with love. Veterinary clinic concept. Services of a doctor for animals, health and treatment of pets dog vet stock pictures, royalty-free photos & images

How to prevent MCTs in your dog

While it is not possible to completely prevent the occurrence of mast cell tumors (MCTs) in dogs, there are certain measures you can take to potentially reduce the risk or detect them early. Here are some tips for MCT prevention:

Regular Veterinary Check-ups

Schedule routine veterinary examinations for your dog, including thorough physical examinations. Regular check-ups allow your veterinarian to detect any abnormalities or changes, including the presence of skin lumps or masses that may require further investigation.

Skin Checks

Perform regular skin checks on your dog. Pay attention to any new lumps, bumps, or skin changes, including changes in color, texture, or size. If you notice any concerning growths or changes, consult with your veterinarian promptly.

Prompt Veterinary Evaluation

If you discover a lump or suspect a mast cell tumor, seek veterinary attention promptly. Early detection and diagnosis are crucial for effective treatment and better outcomes.

Minimize Exposure to Potential Carcinogens

Limit your dog's exposure to potential environmental carcinogens, such as pesticides, herbicides, and other harmful chemicals. Avoid exposing your dog to tobacco smoke or other known carcinogens.

Healthy Diet and Lifestyle

Provide your dog with a balanced and nutritious diet to support overall health and immune function. Regular exercise and maintaining a healthy weight can also contribute to overall well-being.

Flat lay of Kabo tender chicken cooked dog food with fresh human grade ingredients displayed around

Avoid Self-Mutilation

Discourage your dog from excessive licking, scratching, or biting at their skin. Chronic self-trauma can irritate the skin, potentially leading to inflammation and the formation of skin masses.

Early Intervention

If your dog has a history of mast cell tumors or is considered predisposed, discuss with your veterinarian the possibility of additional monitoring or preventive measures tailored to your dog's individual circumstances.

While these preventive measures can help with early detection and potential risk reduction, it is important to remember that MCTs can still occur despite taking precautions. Regular veterinary care and open communication with your veterinarian are key in maintaining your dog's health and addressing any concerns promptly.

Always consult with your veterinarian for personalized advice and guidance on preventive measures specific to your dog's breed, age, and overall health.

Black poodle casually laying outside
Black poodle casually laying outside

View Sources

London, Cheryl A., and Bernard Seguin. "Mast cell tumors in the dog." Veterinary Clinics: Small Animal Practice 33, no. 3 (2003): 473-489.

O’Keefe, Deborah A. "Canine mast cell tumors." Veterinary Clinics of North America: Small Animal Practice 20, no. 4 (1990): 1105-1115.

Govier, Susanne M. "Principles of treatment for mast cell tumors." Clinical techniques in small animal practice 18, no. 2 (2003): 103-106.

Thompson, J. J., D. L. Pearl, J. A. Yager, S. J. Best, B. L. Coomber, and R. A. Foster. "Canine subcutaneous mast cell tumor: characterization and prognostic indices." Veterinary Pathology 48, no. 1 (2011): 156-168.

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