Mast Cell Tumor Vs Lipoma: The Truth About Lumps on Your Dog

Mast cell tumors and lipomas are both common canine skin masses that can be easily confused, but they differ in their malignancy and treatment options. Dogs can develop various lumps and bumps on their skin, and two of the most common ones are mast cell tumors and lipomas.

While both can feel similar to the touch, the biggest difference between them is that mast cell tumors are cancerous and can spread to other tissues, while lipomas are benign and do not metastasize. Identifying the type of mass is crucial to determine the best course of action.

In this article, we will go over the characteristics and treatment options for both mast cell tumors and lipomas in dogs, so pet owners can make informed decisions about their furry friend’s health.

Mast Cell Tumor Vs Lipoma: The Truth About Lumps on Your Dog


Mast Cell Tumor: What Is It?

Mast cell tumors and lipomas in dogs are two common types of skin growths that pet owners often notice. While lipomas are generally harmless, mast cell tumors can be more problematic. In this section, we’ll explore what mast cell tumors are, their common locations, what causes them, and the symptoms and treatments.

Definition Of Mast Cell Tumor

Mast cell tumors are a type of cancerous growth that can occur in dogs. Specifically, these tumors develop from cells called mast cells, which are a normal and important part of the immune system. Mast cell tumors can occur anywhere on a dog’s body, including the skin, internal organs, and bone marrow.

Common Locations Of Mast Cell Tumor On Dogs

The most common locations for mast cell tumors in dogs include:

  • On or under the skin, particularly on the trunk, limbs, and head
  • In the spleen
  • In the liver
  • In the gastrointestinal tract

What Causes Mast Cell Tumor In Dogs?

The exact cause of mast cell tumors in dogs is unknown, but several factors may increase a dog’s risk of developing them. These include:

  • Age: Mast cell tumors are more common in older dogs
  • Breed: Certain breeds, such as boxers, bulldogs, and pugs, are at a higher risk
  • Genetics: There may be a hereditary component to mast cell tumor development
  • Exposure to certain chemicals or toxins

How Common Is Mast Cell Tumor In Dogs?

Mast cell tumors are one of the most common types of skin tumors in dogs, accounting for approximately 20% of all skin tumors. They are more common in dogs over the age of 8 and occur more frequently in certain breeds.

Symptoms Of Mast Cell Tumor In Dogs

The symptoms of a mast cell tumor can vary depending on the location of the tumor. Common symptoms include:

  • A lump or mass on the skin that may or may not be painful
  • Swelling
  • Irritation or itchiness around the tumor
  • Gastrointestinal symptoms, such as vomiting or diarrhea
  • Signs of anemia, such as pale gums and lethargy
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Diagnosing Mast Cell Tumor In Dogs

If you suspect that your dog may have a mast cell tumor, it’s important to make an appointment with your veterinarian. Your vet may use different techniques to diagnose mast cell tumors, including:

  • A physical exam
  • Blood tests
  • Imaging tests, such as X-rays or ultrasounds
  • Biopsy

Treatment For Mast Cell Tumor In Dogs

The treatment for a mast cell tumor will depend on the location and severity of the tumor. In general, treatment options may include:

  • Surgery to remove the tumor
  • Radiation therapy
  • Chemotherapy
  • Palliative care

It’s important to note that the prognosis for dogs with mast cell tumors can vary widely depending on the specific situation. Early detection and treatment can help improve outcomes.

Lipoma: What Is It?

Mast cell tumors and lipomas are two common types of lumps that can grow under your dog’s skin. Understanding the difference between them can help you ensure that your furry friend receives the best care possible.

Definition Of Lipoma

A lipoma is a soft, fatty lump that develops under the skin. They are usually benign and don’t pose any serious health risks to your dog. However, they can sometimes grow quite large, causing discomfort and mobility issues.

Common Locations Of Lipoma On Dogs

Lipomas can appear anywhere on your dog’s body, but they are most commonly found on the trunk, shoulders, and upper legs. They can also develop in the chest cavity or the abdominal organs, although this is less common.

What Causes Lipoma In Dogs?

It’s not entirely clear what causes lipomas to develop in dogs. Some experts believe that genetics play a role, while others suggest that obesity or hormonal imbalances could be contributing factors.

How Common Is Lipoma In Dogs?

Lipomas are very common in dogs, especially in middle-aged and older animals. They can develop in any breed, but they are more common in certain breeds such as labrador retrievers, Doberman pinschers, and miniature schnauzers.

Symptoms Of Lipoma In Dogs

Most lipomas are asymptomatic, which means that they don’t cause any noticeable issues for your dog. However, some signs that could indicate a lipoma include:

  • A soft, movable lump under the skin
  • Swelling or enlargement of the lump over time
  • Lumps that feel warm or irritated to the touch

Diagnosing Lipoma In Dogs

To diagnose a lipoma, your veterinarian will perform a physical exam, which may include taking a sample of the lump for testing. In some cases, a biopsy may be needed to rule out other conditions.

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Treatment For Lipoma In Dogs

In many cases, lipomas do not require treatment and can be left alone if they are not causing any issues for your dog. However, if the lump is growing rapidly or is interfering with your dog’s mobility, your veterinarian may recommend surgical removal. This is usually a straightforward procedure with low risk.

Differences Between Mast Cell Tumor And Lipoma

Mast cell tumors (MCT) and lipoma are common skin masses found in dogs. While both can cause lumps on dogs, they differ in appearance, consistency, texture, growth rate, and potential risks and complications. Let’s take a closer look at the distinctive characteristics of mast cell tumors and lipoma in the following paragraphs.

Distinctive Characteristics Of Mast Cell Tumor And Lipoma

Mast cell tumor:

  • A mast cell tumor is a cancerous growth and can appear as single or multiple lumps on the dog’s skin.
  • These tumors are often red, swollen, and irritated in appearance.
  • The size of the tumor can range from small to large, and they tend to grow quickly.
  • They can be located anywhere on the body, both externally and internally.
  • Mcts are also more likely to spread to other parts of the body, including the lymph nodes, liver, spleen, bone marrow, and gastrointestinal tract.


  • A lipoma is a benign fat tumor and is often soft, squishy, and moveable to the touch.
  • They can grow anywhere on a dog’s body where there is fatty tissue.
  • The size of the lump can range from small to large, and they tend to grow slowly.
  • They are typically painless, but can occasionally cause discomfort if they press on nearby organs.
  • Lipomas rarely spread to other parts of the body.

Differences In Appearance, Consistency, And Texture

Mast cell tumors and lipomas differ in their appearance, consistency, and texture.

  • Mcts are usually red and swollen in appearance and can have a wide range of consistencies, with some feeling rubbery, while others are firm and hard.
  • Lipomas, on the other hand, are typically soft, squishy, and moveable to the touch. They are also yellowish or white in appearance.

Differences In Growth Rate And Spread

Mast cell tumors and lipomas also differ in their rate of growth and their propensity to spread.

  • Mcts tend to grow more aggressively than lipomas, and they can spread and metastasize to other parts of the body quickly.
  • Lipomas, however, typically grow slowly and rarely spread.

Differences In Potential Risks And Complications

Mast cell tumors can carry the risk of severe complications, such as:

  • Bleeding and ulceration
  • Intestinal obstruction
  • Anaphylaxis
  • Widespread metastasis

Lipomas, however, are considered to be relatively safe, and the only real concern is if they grow to a size that starts impacting the dog’s mobility or if they are located in an area that might need removal for cosmetic or safety reasons.

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Understanding the differences between mast cell tumors and lipoma is vital for dog owners as early detection and proper treatment can be the key to a successful outcome. If you discover any lumps on your dog’s body, never hesitate to contact your veterinarian for expert advice.

FAQ For Mast Cell Tumor Vs Lipoma Dog

What Is A Mast Cell Tumor In Dogs?

Mast cell tumors are the most common skin tumors in dogs. They originate from mast cells in the body and can spread to other organs if left untreated.

What Is A Lipoma In Dogs?

A lipoma is a non-cancerous tumor composed of fat cells that typically grow slowly and don’t spread. They are common in older dogs and usually don’t require treatment.

How Can I Tell If My Dog Has A Mast Cell Tumor Or A Lipoma?

A veterinarian can perform a physical exam, biopsy, and imaging to determine whether the lump is a mast cell tumor or lipoma. Mast cell tumors may feel firmer and be more likely to appear red and inflamed than lipomas.

Can Mast Cell Tumors And Lipomas Coexist In A Dog?

Yes, a dog can have a mast cell tumor and a lipoma at the same time, especially as they age. It’s important to have any lumps or bumps examined by a veterinarian for proper diagnosis and treatment.

What Is The Treatment For Mast Cell Tumors And Lipomas In Dogs?

Treatment for mast cell tumors varies depending on the grade and location of the tumor. Surgery is the most common treatment, but chemotherapy or radiation may also be recommended. Lipomas usually don’t require treatment, but surgical removal may be recommended if they’re causing discomfort or affecting mobility.


Ultimately, distinguishing between a mast cell tumor and a lipoma in a dog can be difficult even for experts. However, it’s crucial to identify the right diagnosis as soon as possible. Mast cell tumors require prompt treatment to prevent them from spreading and becoming life-threatening, whereas lipomas are typically benign and just require monitoring.

If you notice any lumps or bumps on your dog’s body, it’s always best to take them to a veterinary professional who can perform an accurate diagnosis. Remember to monitor any changes in the appearance or behavior of these lumps as they could indicate a more serious or possibly fatal condition. Keeping your furry friend healthy and happy should always be a top priority, so make sure to stay vigilant and aware of any abnormalities in your dog’s physical health.