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Mast Cell Tumor In Dogs - Symptoms, Prognosis and Treatment

María Besteiros
By María Besteiros, Expert veterinary assistant and canine/feline hairdresser.. Updated: February 18, 2019
Mast Cell Tumor In Dogs - Symptoms, Prognosis and Treatment

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Mastocytoma in dogs is a common type of skin tumor in dogs which can appear either benign or malignant. Although it usually affects older dogs of any breed, brachycephalic dog breeds, such as boxers or bulldogs, are more prone to developing mastocytoma. Prognosis and treatment of mast cell tumor in dogs depends on the size, appearance and location of the tumor. Treatment for mast cell tumor in dogs can include surgery, drugs, radiotherapy or chemotherapy.

Are you wondering what mast cell tumor looks like? What about the symptoms, prognosis and treatment of mastocytoma? For everything you need to know about mast cell tumors in dogs, keep reading here at AnimalWised.


  1. Mast cell tumor in dogs
  2. Mast cell tumor in dogs: symptoms
  3. Mast cell tumor in dogs: diagnosis
  4. Mast cell tumor: dog life expectancy
  5. Mast cell tumor in dogs: treatment

Mast cell tumor in dogs

Cutaneous mastocytomas in dogs are mast cell tumors, cells with immune function. They intervene, among other things, in allergic processes and wound healing. These cells contain histamine and heparin which the body releases as a response to allergens and inflammation. In fact, these mastocytomas release histamine, related to the appearance of gastrointestinal ulcers, which actually one of the main symptoms of mast cell tumors in dogs. Although less frequent, they can also cause coagulation problems due to the release of heparin.

Causes of mast cell tumors are often linked to hereditary components, genetic factors, viruses or trauma. However, often the cause remains unknown. These tumors are common in male and female dogs over the age of nine.

For more, we recommend reading skin tumors on dogs.

Mast cell tumor in dogs: symptoms

Mastocytomas are lumps that we can be located on different parts of a dog’s body but are more common on the torso and perineal area. Its appearance, as well as its consistency, is very variable, independent of whether it is malignant or benign. Thus, there can be one or multiple nodules, slow or fast growing, with or without metastasis, etc. This means that whenever you find any lesion of this type on your dog’s skin consider it a mast cell.

The tumor may ulcerate, redden, become inflamed, irritated, bleed, promote hair loss and grow or shrink in size. Mast cell tumor in dog symptoms include:

  • Scratching.
  • Visible lesions and growths.
  • Redness and/or bruising on the skin.
  • Gastrointestinal ulcers that cause symptoms such as vomiting, diarrhea, anorexia, blood in the stool or anemia.


Mast Cell Tumor In Dogs - Symptoms, Prognosis and Treatment - Mast cell tumor in dogs: symptoms

Mast cell tumor in dogs: diagnosis

A veterinarian can confirm a diagnosis by cytology, which means taking a tumor sample with a fine needle. A vet will also have to asses whether metastasis is present by examining the nearest lymph node. In addition, blood and urine examinations and spleen and liver ultrasounds may need to be performed, as sometimes the canine mast cell can spread. In addition, pleural effusions (water on the lungs) and ascites (fluid build-up in the abdomen) may be present. Mastocytoma, although not very common, can also affect a dog’s bone marrow.

A biopsy can also provide the necessary information needed on the nature of the mastocytoma, allowing for a reliable prognosis and treatment.

For more, we recommend taking a look at our article cancer in dogs.

Mast Cell Tumor In Dogs - Symptoms, Prognosis and Treatment - Mast cell tumor in dogs: diagnosis
Image: cliniciansbrief.com

Mast cell tumor: dog life expectancy

One of the most common questions asked when it comes to mastocytomas in dogs is, what is mast cell tumor dog life expectancy? The life expectancy of dog with mast cell tumor will depend on the pathological classification of the tumor. There are different degrees of malignancy (grade), from I to III, which define the tumors severity:

  • Grade I: Appear on the skin and are not very deep. They can sometimes be difficult to remove, but are less likely to spread.
  • Grade II: Grow into subcutaneous tissue under the skin.
  • Grade III: Much deeper within the skin and extremely aggressive.

Some dog breeds are naturally prone to more severe cases of mast cell tumors. These breeds include brachycephalic dog breeds, golden Retrievers, Labradors, and Cocker Spaniels. Boxer are the only exception, as they usually develop differentiated mastocytomas. If you are not sure which dog breeds are brachycephalic, we recommend reading our brachycephalic dog breeds list.

The tumors which are the most aggressive are often the least differentiated. In most cases, surgery cannot extract these tumors as they are too far infiltrated within the skin. The average lifespan of mast cell tumor in dogs suffering from Grade III tumors, without the necessary treatment, is only a few weeks. Few dogs with severe mastocytoma survive a year. In these such cases, treatment will only be palliative[1].

In addition, the lympth node involvement in the staging of the mast cell tumor is necessary to know when analyzing the severity of the mastocytoma. Often, however, it is important to know that mast cell tumors are incredibly unpredictable. Therefore, establishing a prognosis is very difficult and can take time.

Mast cell tumor in dogs: treatment

Again, treatment will depend on the type, grade and characteristic of the mast cell tumor. If your are faced with a solitary tumor, well-defined without metastasis, surgery is likely. Sometimes, however, the substances released by the tumor may delay surgical wound healing. It is also important that the extraction includes a margin of healthy tissue. These such cases have a more favorable prognosis, although recurrences are sometimes possible. If, after surgery, tumor cells remain on the healthy border, it will be necessary to re-intervene[2].

Sometimes it’s not possible to leave this above mentioned margin or the tumor is extremely large and difficult to fully remove. If this is the case, additional drugs or treatment are prescribed, such as prednisone and/or chemo/radiotherapy. Chemotherapy is commonly used in multiple or disseminated mastocytomas. For more about canine chemotherapy, we recommend reading our article about chemotherapy in dogs and what you need to know.

Mast Cell Tumor In Dogs - Symptoms, Prognosis and Treatment - Mast cell tumor in dogs: treatment

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Mast Cell Tumor In Dogs - Symptoms, Prognosis and Treatment, we recommend you visit our Other health problems category.


1 Ríos, A. (2008): "Mastocitoma canino y felino", Clín. Vet. Peq. Anim., 28 (2), 135-142

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Mast Cell Tumor In Dogs - Symptoms, Prognosis and Treatment