What You Need to Know About Mast Cell Tumor In Dogs

Abdominal ultrasound evaluation of benign and malignant mast cell tumours form

For many pet owners, discovering that their beloved animal companion is facing a serious illness is deeply distressing. Unfortunately, similar to people, pets are also prone to being diagnosed with cancer, which encompasses the risk of developing mast cell disease. The most crucial approach to tackle this issue is to:

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 i, grade ii tumors, grade iii, and grade iv)

Step 4: Suitable treatments involving procedures 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 type of white blood cell (those that assist the body in wound healing) that is normally found in many tissues. It is a cancerous accumulation of granulocytes 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, a mast cell is a white blood cell that appears 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, preventing allergic reactions, and also helping 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 have a high rate of spread to different parts of their body (metastasis). Subcutaneous tumors also often precede visceral mast cell disease.

Symptoms Of Mast Cell Cancer In Dogs

So, what does an MCT look like, and what are the signs to watch out for? 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.

They may also fluctuate in size, getting larger or smaller daily. This happens because of the agitation of the tumor, which causes degranulation and swelling of the surrounding tissue.

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?

Canine mast cell tumors (MCTs) are more commonly found in the skin as well as the subcutaneous tissues and account for 16–21% of all canine skin tumors. Dog mast cell tumors can also originate from other regions such as the mouth, liver, spleen, bone marrow, or gastrointestinal tract, but they are mostly found on the skin and usually spread to the lymph nodes (resulting in enlarged lymph nodes) and internal organs.

When mast cell tumors 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. Additionally, cutaneous mast cell tumors can also spontaneously regress, while higher-grade tumors tend to metastasize, which occurs first at the local lymph nodes.

Most tumors occur alone, but boxers and pug breeds have an increased predilection for multiple skin tumors. These tumors are often noticed in the skin and subcutaneous tissue. MCTs can also be mistaken for an insect bite or an allergic reaction.

What Causes Mast Cell Tumors In Dogs?

The cause of canine MCTs or any other form of tumor is unknown. Very few types of cancer (like common malignant skin cancer) have a known cause. In most cases, they are caused by a complex combination of risk factors (including both genetic and environmental ones) and are the most common skin tumors in dogs.

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 Retrievers, 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 determine the type of treatment needed. After the tumor is completely removed, the biopsy will provide the veterinary oncologist with more information about the tumor’s grade. The staging of MCTs 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 the pet’s mast cell tumors 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 cell 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 for more information. The information provided will help the veterinary oncologist determine the organs that have most likely been affected by cancer and proceed with providing veterinary medicine.

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 the cancer.

The veterinarian may also take a sample from the bone marrow, lymph node, or kidney. Abdominal organ ultrasound and chest X-rays may also be used to identify the site and clinical 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.

A biopsy or needle aspiration is necessary to determine the best treatment options in a given case, such as surgical excision of the primary tumor, radiation therapy, or chemotherapy drugs, so that you can get a good idea of the expected mast cell tumor dog life expectancy. Radiation therapy is an option to go for if the mass is not in a suitable location for surgical removal or if the primary tumor is not completely removed. Dogs typically tolerate both radiation therapy and chemotherapy well, although there is a risk that the radiation therapy will also damage the healthy tissue surrounding the tumor.

Determining the staging of cancer helps your primary care veterinarian decide which treatment method is required. Generally, prognostic factors that help pet owners 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. Most commonly, surgical removal is the preferred treatment option if there’s no evidence of spread. Such treatment is more effective for low-grade patients. Some cutaneous mast cell tumors will spontaneously regress.

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, which determines the margin of normal cells. Aggressive local therapy combined with systemic chemotherapy also provides long-term control for grade II MCTs and higher-grade tumors.

Low-grade tumors that are completely removed with adequate margins usually do not need further therapy or surgical removal. Nonetheless, pups that show high-grade MCTs (grade iii tumor) or those with evidence of the 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. A procedure called “wide resection” also completely removes the tumor and the surrounding tissues.

Several drugs could be used for dogs’ mast cell tumors, including traditional therapies (Lomustine, vinblastine), RTK inhibitors (Kinavet, Palladia, toceranib phosphate), and steroids. The protocol followed by a veterinary oncologist will vary considerably, along with the involvement of multiple drugs. Occasionally, antibiotics are prescribed if a fever is associated with a pet having a low white blood cell count since an infection is possible.

If your pets have canine mast cell tumors, they may be placed on a variety of supportive medications during 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. The removal of grade II tumors generally requires follow-up treatment.

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.

A dog diagnosed with MCT before is at increased 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 life. Palliative therapy is used to reduce the symptoms of a pet’s mast cell tumor 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 tumor 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 in other regions of the body, including the stomach. Weight loss resulting from the 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, dog mast cell tumors can be cured. These tumors are often treated with modern therapy using radiation therapy, 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 age, diet, health history, tumor location, how far it has spread, and what treatment methods are used.

When should we stop fighting mast cell tumors in dogs?

When to stop fighting mast cell tumors in dogs is normally the end of cancer. However, this does not apply to some other kinds of tumors. The most common tumors are 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 tumors 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 it’s strongly recommended that you 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 a suitable diet for a dog who has a mast cell tumor?

A suitable diet for dogs who have mast cell tumors 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 pets grow mast cell tumors. There’s some debate that tumors develop due to inflammation or skin disease, but this has not been proven. Dog 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 dogs with mast cell tumors 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.

The post What You Need to Know About Mast Cell Tumor In Dogs first appeared on Well Pet Coach.