How Do You Tell If A Lump On A Dog Is A Fatty Tumor?

Fatty tumors, also known as lipomas, are benign masses of fatty tissue that frequently form under the skin of middle-aged and older dogs. While often harmless, fatty tumors can sometimes grow large enough to impact movement or even become cancerous, so it’s important for dog owners to regularly monitor their pets for any lumps or bumps. This article provides an overview of the causes, symptoms, diagnosis, and treatment options for fatty tumors in dogs.

What are fatty tumors?

Fatty tumors, also known as lipomas, are benign tumors composed of mature fat cells and connective tissue that form lump-like growths under the skin (Szanecki, 2017). Unlike cancerous tumors, lipomas are not malignant and do not metastasize to other parts of the body.

Lipomas are typically soft, movable, and painless growths that form between the skin and underlying muscle layer. They occur most often in middle-aged and older dogs, especially obese dogs. While benign fatty tumors rarely cause any problems on their own, their appearance may sometimes raise concerns that the lump could be cancerous (, 2022).

Common locations

Fatty tumors, also known as lipomas, most commonly develop on a dog’s torso, although they can grow anywhere on the body. Some of the most common locations include:

Under the skin on the chest and abdomen – This is the most frequent area for lipomas to develop. The chest and belly have abundant fat deposits under the skin, which is where lipomas form.

Legs – Lipomas often form on the inner thighs and upper legs. They grow in areas with extra fat content.

Armpits and groin – The folds of a dog’s armpits and groin are also prone to lipoma development.

Neck and shoulders – While less common, lipomas can sometimes grow on the neck, shoulders, and upper back.

Fatty tumors can vary greatly in size and location, but the torso is the most prevalent region. Monitoring lumps in areas where your dog has extra fat under the skin can help identify potential lipomas. However, lipomas can develop almost anywhere on the body.

Breed predispositions

Certain dog breeds seem to be more prone to developing fatty tumors based on research. Studies have found some of the highest rates of lipomas in Weimaraners (7.84%), Doberman Pinschers (6.96%), German Pointers (5.23%), and Springer Spaniels (5.19%) [1]. Overweight female dogs also tend to be more susceptible [2].


The exact cause of fatty tumors in dogs is not fully understood, but there are several factors that may contribute to their development:

Genetics – Certain breeds like Doberman Pinschers, Labrador Retrievers, Miniature Schnauzers, and Beagles seem predisposed to developing lipomas. This suggests there may be a genetic component.

Diet – Fatty tumors are more common in overweight or obese dogs. Excess fat cells may trigger tumor growth. High carb diets that lead to insulin resistance may also play a role.

Age – Lipomas usually develop in middle-aged to older dogs, between 6-10 years old. The risk increases as dogs age.

Inflammation – Chronic inflammation is linked to tumor development. Allergies, arthritis, and other sources of inflammation may contribute.

Hormones – Hormonal imbalances may increase fatty tumor risk. Dogs spayed/neutered at an early age are more prone to lipomas.

Trauma – Injury to tissue may potentially trigger the development of a fatty mass.

Overall, the tendency to develop lipomas likely involves multiple factors. Genetics, diet, hormones, and age seem to be the most significant risk factors according to current research.



The most common symptom of a fatty tumor is a soft, movable lump under the dog’s skin [1]. These lumps are usually round or oval shaped and are not attached to underlying tissues. Fatty tumors are often painless, though larger growths may cause discomfort if they press on nerves or muscles [2].

Additional symptoms that may indicate a fatty tumor include:

  • A lump that can be moved under the skin and feels soft or rubbery [3]
  • A lump that is often dome-shaped and found just under the skin
  • Changes to the lump over time, including growth in size
  • Occasional fluid discharge if the tumor ruptures
  • Loss of hair over the surface of the lump

Common locations for fatty tumors include the trunk, legs, armpits, and abdomen. Dogs may develop multiple tumors over time. If the lump interferes with movement or shows signs of inflammation, veterinary examination is recommended.


Veterinarians will diagnose fatty tumors through a physical examination of the lump, looking at its appearance and feel. They will check if it moves easily under the skin and if it feels soft and rounded. However, a physical exam alone cannot definitively diagnose a fatty tumor, as some cancers like liposarcomas can also feel soft and moveable (FirstVet).

The only way to conclusively diagnose a fatty tumor is to perform a fine needle aspirate and cytology. This involves inserting a small needle into the lump, extracting some cells, staining them, and examining them under a microscope. Fatty tumors will show an abundance of fat cells and no signs of abnormal cell growth. If the results are inconclusive, the vet may recommend surgical removal of the lump and biopsy for a complete diagnosis (Pawlicy).


The main treatment for fatty tumors in dogs is surgical removal. Surgery is recommended if the lump is growing quickly, interfering with movement or bodily functions, ulcerated or inflamed, or suspected to be cancerous. However, surgery may not be necessary for every case.

For small non-bothersome fatty tumors, veterinarians often recommend monitoring the lump and leaving it alone. Dogs can live normal lives with fatty tumors as long as they don’t cause problems. Periodic examinations help ensure the lump is not growing or changing.

Some holistic vets recommend non-surgical options to treat fatty tumors in dogs. These may include: dietary changes, nutritional supplements, herbal remedies, homeopathy, acupuncture, and using topical products containing ingredients like castor oil, essential oils, and CBD oil. However, there is limited evidence on the effectiveness of these alternative treatments.

According to Dr. Magda on, taking an integrative approach can help shrink lipomas and prevent their recurrence. This involves optimizing diet, reducing inflammation, supporting the immune system, and using natural therapies.


While there is no guaranteed way to prevent fatty tumors in dogs, there are some steps owners can take that may help reduce the risk of their dog developing them:

Maintaining a healthy weight – Overweight and obese dogs tend to be more prone to fatty tumors, so keeping your dog at an ideal weight can be beneficial. Feeding a nutritious diet and ensuring your dog gets adequate exercise can help maintain a healthy weight.

Providing antioxidant support – Antioxidants help protect cells from damage. Including antioxidant-rich foods like fruits, vegetables, and fish in your dog’s diet may offer some preventative effects against fatty tumor development.

Monitoring hormone levels – Reproductive hormones may influence fatty tumor growth rates in some dogs. Discussing preventative spay/neuter options with your veterinarian can potentially reduce this risk.

Limiting carbohydrates – Some research indicates that diets high in carbohydrates may increase the likelihood of fatty tumor development in dogs. Limiting carbs and grains in your dog’s diet may help reduce the chances of fatty tumors forming.

However, the exact causes of fatty tumors in dogs are not fully understood. Even with preventative steps, some dogs may still develop fatty tumors. Alerting your vet to any new lumps forming can allow for early evaluation and treatment if they are found to be fatty tumors.



The long-term outlook for dogs with fatty tumors is generally quite good. Fatty tumors, or lipomas, are typically benign and do not spread to other areas of the body. According to the VCA Animal Hospitals, once removed, the likelihood of recurrence is relatively low. However, it is common for middle-aged to older dogs to develop multiple fatty tumors over time.

Some large fatty tumors that are infiltrating or putting pressure on surrounding tissues may require more invasive surgery and carry higher risks of complications like nerve damage or recurrence. However, the prognosis is still good if the entire tumor can be fully removed. According to a clinical study published in the National Library of Medicine, complete surgical excision resulted in resolution without recurrence in most cases.

While some fatty tumors may grow quite large, they usually do not negatively impact a dog’s health or quality of life. Dogs can live normal lifespans with benign fatty tumors. Only in very rare cases where the tumor interferes with vital functions or cannot be fully removed would the prognosis be more serious.

Overall, with routine monitoring and proper treatment if needed, most dogs have an excellent long-term outlook and live happily with fatty tumors.

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