What You Need to Know about Mast Cell Tumor Dog

Well Pet - MCT Feature Image

For many pet owners, knowing that your pet is suffering from life-threatening illness is a piece of devastating news. Unfortunately, just like humans, the diagnosis of cancer could happen in pet animals as well. The most important way to tackle such an issue is:

Step 1: Understanding the factors for early detection

Step 2: Evaluation for further diagnosis

Step 3: Prognosis based on the progression of tumor grade (grade 1, grade 2, grade 3, and grade 4)

Step 4: Suitable treatments involving procedure such as radiation treatment (also known as radiation therapy), chemotherapy, or surgery

Stay with us as we continue to elaborate on them further.

What Is a Mast Cell Tumor?

A mast cell tumor (MCT) is a cancerous accumulation of granulocyte that originates from the dog’s bone marrow. Although these tumors usually reside in the skin, they can affect the internal organs as well. Typically, mast cells are white blood cells that appear closer to external surfaces such as the nose, mouth, and lungs.

These mast cells contain granules, which include heparin, histamine, proteases, and other chemicals and substances. They are responsible for protecting the body against any pathogenic infestations, prevent allergic reactions, and also help stimulate the formation of blood vessels.

In some cases, these cells can grow into tumors that could result in serious health complications later in a dog’s life. Thus, early detection is vital. These tumors come in different forms, such as relatively harmless (benign) and more life-threatening (malignant) forms. Some have high recurrence rates, while others tend to spread to different parts of their body (metastasis).

Abdominal ultrasound evaluation of benign and malignant mast cell tumours form

Symptoms Of Mast Cell Cancer In Dogs

So, what does a mast cell tumor look like, and what are the signs to watch out? These tumors can develop anywhere on the body and vary significantly in appearance. They can be raised lumps on or below the skin, which may be swollen, red, and ulcerated. Some signs may develop slowly, and some tend to appear overnight.

But how can you tell if your pet’s bump is an MCT? Here are some symptoms to watch out for:

  • The sudden growth of bumps or lumps (tumor growth)
  • A tumor that seems to fluctuate
  • Lumps or bumps that look similar to an insect bite.
  • Enlarged lymph nodes around the affected area
  • Inflamed or itchy bumps/swelling
  • Enlargement of the liver and spleen
  • Lack of appetite or no appetite at all
  • Vomiting
  • Diarrhea or stool changes
  • Lethargy
  • Redness
  • Reduced mobility
  • Panting and rapid breathing

Diagnosis of canine mast cell tumour or non cancerous skin tumors


Where Is the Tumor Commonly Found?

Mast cell tumors are more commonly found in the skin as well as the subcutaneous tissue and account for 16%-21% of all canine skin tumors. MCTs can also originate from other regions such as the mouth, liver, spleen, bone marrow, or the gastrointestinal tract, but they are mostly found on the skin.

When MCTs develop on the skin, they can spread to any other part of the body, including the head, neck, and muzzle. The most common locations of skin tumor spread (metastasis) include the lymph nodes.

What Causes Mast Cell Tumors In Dogs?

The cause of canine mast cell tumor or any other form of tumor is unknown. Very few types of cancers have a known cause. In most cases, they are caused by a complex combination of risk factors (including both genetic and environmental ones).

There are many genetic mutations involved in the development of tumors and their behavior. One known mutation is in a protein that is involved in cell division and replication (known as KIT).

Although any dog breed can develop skin tumor cells, some breeds are more vulnerable. These tumors are more common in Labrador Retriever dogs, Golden Retrievers, Miniature Schnauzers, Boxers, Pugs, Bulldogs, Boston Terriers, and Bull Terriers.

Breeds that you should check its tissue for potential mast cell tumor dog symptoms

Stages of Mast Cell Tumors In Dogs

The biopsy of a mast cell tumor in dogs provides vital information that helps veterinarians to determine the type of treatment needed. The staging of an MCT tells one how large it is and whether or not it has spread to other areas. Usually, the symptoms are determined by the stage of MCTs that occur in the following order:

  • 1: Involves a single tumor that does not metastasize
  • 2: Involves a single tumor that metastasizes in the surrounding lymph nodes [1]
  • 3: Contains multiple tumors or masses
  • 4: It means that the cancerous cells have spread to the organ. Or rather, a widespread mast cells in the blood

Prognosis & Types of Treatments

In the first checkup of the patient, the veterinarian will require the complete health history of your pooch, including his previous diseases and a history of the signs and symptoms of each condition. The information provided will help your vet to determine the organs that have most likely been affected by cancer.

Most canine mast cell tumors are successfully diagnosed with a fine needle aspirate (FNA). A biopsy of the mass might be taken to confirm the grade of the cells, along with a diagnosis to determine the extent of cancer.

The veterinarian may also take a sample from the bone marrow, lymph node, or the kidney. Abdominal ultrasound and chest x-rays may also be used to identify the site and staging of cancer. Other possible tests include a blood count and a urine test. The very first examination will involve an assessment of the cells.

Biopsy/needle aspiration is necessary to determine the best treatment options in a given case, such as surgical excision, radiation, or chemotherapy so that you can get a good idea of the expected mast cell tumor dog life expectancy.

Determining the staging of cancer helps your primary care veterinarian to decide which treatment method is required. Generally, prognostic factors that help pet owners to determine the best treatment recommendations include:

  • The stage of the tumor
  • The tumor grade
  • Completeness of the surgical margins


Generally, low grade canine mast cell tumors have a low rate of spread, while high-grade tumors may be aggressive with high incidences of metastasis. In most cases, surgical removal is the preferred treatment option if there’s no evidence of spread. Such treatment is more effective for low-grade patients.

For mast cell tumor dog prognosis without surgery, radiation therapy can be performed if the surgical margins are not clear for grade III MCTs based on the histopathology report.

Low grade tumors that are entirely removed with adequate margins usually do not need further therapy or surgical removal. Nonetheless, pups that show high grade MCTs or those with evidence of spread of MCTs to the surrounding lymph nodes will need radiation therapy and might also require further treatment, which is also referred to as multi-modality therapy.


There are a number of drugs that could be used for MCTs, including traditional therapies (Lomustine, vinblastine), RTK-inhibitors (Kinavet, Palladia, toceranib phosphate), and steroids. The protocol followed by an oncologist will vary considerably.

If your pets have MCT, they may be placed under a variety of supportive medications in the course of the treatment period. These include a small dose of prednisone, which can eliminate cancerous mast cells and reduce inflammation; antacids like Prilosec or Pepcid; and antihistamines like Benadryl.

Although it has proven to be an effective drug against cancer cells, this type of medication can result in side effects like nausea, vomiting, panting, increased appetite, increased panting, and increased urination.

It can also lead to bleeding, dark stools, and gastrointestinal irritation. On the other hand, antacids have proven to be effective at preventing or reducing some of the above side effects.

Dogs that have been diagnosed with MCT before are at an elevated risk of developing more tumors. Detecting tumors early and addressing them while they are small and local can increase the likelihood of effective treatment.

For mastocytomas that have already spread far or those that develop in areas aside from the skin (including the spleen and the gastrointestinal tract), the prognosis tends to be poor.

The aim of the various treatment options for such patients is to remove the tumors and ensure a high quality of living. Palliative therapy is used to reduce the symptoms of MCTs and provide the best outcome.

After prognosis, veterinarian performs organs surgery on the canine breeds


Frequently Asked Questions

Will a mast cell tumor kill my dog?

A mast cell tumor may not kill your dog. The most common effect of MCTs is a lump or bump. The cancerous cells stimulate the production of numerous chemical mediators (such as neutral proteases, proteoglycans, and histamine). 

Such mediators produce localized effects on cells around the immune system and the blood vessels, which can make the mast cell disease look a lot like an infection or an inflammatory reaction.

However, no two pets are the same. Tumors may bleed and vary in size and appearance from time to time. The mediators can also produce inflammatory effects on other regions of the body, including the stomach. Weight loss resulting from loss of muscle and body fat is often linked to malignant tumors.

Can dogs live with mast cell tumors?

Yes, dogs can live with mast cell tumors. While the majority of tumors are benign and may be successfully treated by surgery, some will spread to other regions of the body – resulting in serious health problems.

Can mast cell tumors be cured?

Yes, mast cell tumors can be cured. These tumors are often treated with modern therapy using chemotherapy or surgery as well as immunomodulation therapy like K9 or similar immune system boosters.

However, it is difficult to predict how a particular pet will respond to modern therapy. The effectiveness of treatment will depend on several factors, including the their age, diet, health history, the tumor location, how far it has spread, and what treatment methods are used.

When to stop fighting mast cell tumors in dog?

When to stop fighting mast cell tumors in dogs are normally the end of cancer. However, this does not apply to some other kinds of tumors. The most common tumors are the Thyroidomas (which affect the chest cavity), with some growing bigger than others. 

Other MCTs will invade the spine. These tumors get larger over time. Cancerous tumors seem to remain in the same location if they have not spread to other areas.

When to stop fighting cancerous dog mast cell tumor is when you notice a considerably large tumor that hasn’t spread to other parts of the body. Such tumors will reduce in size and disappear completely.

If you notice any of the aforementioned signs and symptoms of MCTs, then its strongly recommended to contact a vet as soon as possible. However, when to stop fighting mast cell tumors in your pet will depend on each case. If your dog hasn’t given up, then you should probably continue fighting with them.

What is the suitable diet for dog who has mast cell tumor?

A suitable diet for dogs who has mast cell tumor needs to contain lesser carbs, minimal amounts of easily absorbed sugars, and high quality proteins. The mast cell tumor dog diet should also contain unsaturated fats and Omega-3 fatty acids.


It is not clear why some pet grows mast cell tumors. There’s some debate that tumors develop due to inflammation or skin disease, but this has not been proven. Mast cell tumors mainly affect the skin, so it’s best to have your vet check any lumps or bumps that appear on your pet’s skin.

The key to battling cancer and increasing the life expectancy of dog with mast cell tumor is early diagnosis and immediate start of treatment. If you notice a new lump on your pet, make sure to contact your vet as soon as possible.