Mastocytoma Tumors in Dogs


Mastocytoma tumors, commonly known as mast cell tumors, are a prevalent form of cancer in dogs. These tumors originate from mast cells, which are an essential part of the immune system. While mastocytoma tumors can occur in any breed, they are more commonly found in Boxers, Boston Terriers, Labrador Retrievers, and Golden Retrievers. Understanding the types, signs, and treatment options for mastocytoma tumors is crucial for pet owners and veterinarians alike.


There are three primary types of mastocytoma tumors in dogs: cutaneous, subcutaneous, and visceral.

  • Cutaneous Mastocytoma Tumors: These tumors develop on the skin and are the most common type seen in dogs. They typically present as firm, raised masses that may vary in size and appearance. Cutaneous mastocytoma tumors are often found on the trunk, limbs, or perineal area of the dog.
  • Subcutaneous Mastocytoma Tumors: These tumors develop beneath the skin, often in the deeper layers of tissue. They may feel like soft lumps under the skin and can be more challenging to detect without thorough examination. Subcutaneous mastocytoma tumors can sometimes be mistaken for lipomas due to their similar texture.
  • Visceral Mastocytoma Tumors: These tumors develop in internal organs such as the spleen, liver, or gastrointestinal tract. Visceral mastocytoma tumors are less common than cutaneous or subcutaneous tumors but can be more challenging to diagnose and treat due to their location.


The signs of mastocytoma tumors in dogs can vary depending on the location and severity of the tumor. However, some common signs may include:

  • Visible Masses or Lumps: The presence of firm, raised masses on the skin or beneath the skin.
  • Skin Changes: Redness, swelling, or ulceration of the skin overlying the tumor.
  • Gastrointestinal Symptoms: Vomiting, diarrhea, abdominal pain, or loss of appetite may occur with visceral mastocytoma tumors.
  • Systemic Signs: In advanced cases, dogs may exhibit lethargy, weakness, weight loss, or jaundice.

It’s essential for pet owners to monitor their dogs for any unusual lumps or changes in behavior and seek veterinary attention promptly if any concerning signs are noticed.

Diagnostic Procedures

Diagnosing mastocytoma tumors in dogs typically involves a combination of clinical examination, cytology, imaging studies, and sometimes biopsy. These diagnostic procedures are essential for confirming the presence of a tumor, determining its type and grade, and guiding treatment decisions.

  • Clinical Examination: A thorough physical examination by a veterinarian is the first step in diagnosing mastocytoma tumors. The veterinarian will palpate the dog’s skin and underlying tissues to detect any lumps or masses and assess for signs of inflammation or ulceration.
  • Cytology: Fine-needle aspiration (FNA) or impression smear cytology may be performed to obtain a sample of cells from the suspected tumor. These samples are then examined under a microscope to identify mast cells and evaluate their morphology. Cytology can provide rapid and non-invasive confirmation of a mastocytoma tumor and help determine its grade.
  • Imaging Studies: In cases where there is suspicion of visceral mastocytoma tumors or metastasis, imaging studies such as ultrasound, X-rays, or advanced imaging modalities like computed tomography (CT) or magnetic resonance imaging (MRI) may be performed. These studies can help visualize the extent of the tumor, assess its involvement with surrounding tissues, and identify any spread to other organs.
  • Biopsy: In some cases, particularly if the diagnosis is uncertain or if surgical removal is not immediately feasible, a biopsy may be recommended. A biopsy involves the surgical removal of a tissue sample from the suspected tumor site for histopathological examination. Histopathology allows for a more detailed assessment of the tumor’s characteristics, including its grade, mitotic index, and margins.
  • Blood Tests: Blood tests, including a complete blood count (CBC) and serum biochemistry profile, may be performed to evaluate the dog’s overall health status and assess for any abnormalities that may impact treatment decisions or prognosis.

By combining these diagnostic procedures, veterinarians can accurately diagnose mastocytoma tumors, determine their severity, and develop an appropriate treatment plan tailored to the individual needs of the dog. Early diagnosis and intervention are crucial for optimizing treatment outcomes and improving the prognosis for dogs affected by mastocytoma tumors. Regular monitoring and follow-up examinations are essential to monitor treatment response and detect any signs of recurrence or progression.

Treatment Options for Mastocytoma Tumors:

The treatment approach for mastocytoma tumors in dogs typically involves a combination of surgical excision, chemotherapy, and supportive care. The specific treatment plan will depend on factors such as the tumor’s location, size, grade, and whether it has spread to other parts of the body.

Surgical Excision: For localized tumors, surgical removal is often the primary treatment option. The goal is to remove the tumor with wide margins to reduce the risk of recurrence. In some cases, additional surgery may be necessary if the tumor is large or has infiltrated surrounding tissues.

Chemotherapy: In cases where the tumor is aggressive or has spread to other parts of the body, chemotherapy may be recommended to help shrink the tumor and slow its progression. Chemotherapy drugs commonly used for mastocytoma tumors include vinblastine, lomustine, and prednisone.

Radiation Therapy: In certain cases, radiation therapy may be used either as a primary treatment or in combination with surgery and chemotherapy. Radiation therapy can be particularly beneficial for tumors that are not amenable to surgical removal or have a high risk of recurrence.

Supportive Care: Throughout the treatment process, supportive care is essential to help manage symptoms and improve the dog’s quality of life. This may include pain management, nutritional support, and monitoring for any potential side effects of treatment.

In conclusion, mastocytoma tumors are a significant health concern for dogs, requiring prompt diagnosis and appropriate treatment. By understanding the types, signs, and treatment options for mastocytoma tumors, pet owners can work closely with their veterinarians to provide the best possible care for their beloved canine companions. Regular veterinary examinations and proactive monitoring are essential for early detection and intervention, ultimately improving the prognosis for dogs affected by mastocytoma tumors.



Any other doubt? We are here to help, Contact us now.