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  • A lipoma is a benign (noncancerous) mass made of fat cells.
  • These lumps may appear just under the skin anywhere on the body or inside the chest and abdomen.
  • Middle-aged and older female dogs are more likely to have lipomas.
  • All skin lumps should be examined by a veterinarian.
  • A lipoma is diagnosed with a fine needle aspirate or biopsy sample.
  • Since most lipomas are harmless, surgical removal is only necessary if they are large enough to cause discomfort or interfere with walking.

What Is a Lipoma?

A lipoma is a benign (noncancerous) mass that is made of fat cells. Owners often notice these lumps on the chest, abdomen, and limbs of their pets, but lipomas can also occur inside the chest and abdomen.

Middle-aged and older dogs, such as Labrador retrievers, Weimaraners, and Doberman pinschers, are more likely to have lipomas, although they can occur in any breed. Female dogs may be more likely than males to have lipomas. These fatty masses rarely occur in cats.

Unlike cancerous tumors, lipomas do not metastasize (spread throughout the body). Lipomas may appear alone, but dogs may have multiple fatty lumps. The exact cause of these masses is unknown.

Although lipomas are relatively harmless, dogs may develop other skin lumps that are more serious. You should never assume that any lump is a lipoma. A veterinarian should examine any new skin lump, especially those that change in appearance or grow rapidly.

What Are the Signs of a Lipoma?

Lipomas are typically round and soft, although some may be firm. These masses usually do not cause pain, unless they become large and interfere with the limb movement during walking or they affect organs inside the body.

How Is a Lipoma Diagnosed?

There’s no way to tell if a mass is a lipoma just by examining it. Your veterinarian will usually collect a fine needle aspirate, which involves inserting a needle into the mass and extracting cells. These cells are then examined under a microscope. Because fine needle aspirate samples are fairly small, some veterinarians may prefer to perform a biopsy of the mass to confirm a diagnosis.

These same tests will help your veterinarian differentiate a lipoma from a liposarcoma, which is a cancerous tumor arising from fat cells. Liposarcomas, which are uncommon, can invade local tissues and spread to other parts of the body.

How Is a Lipoma Treated?

Since lipomas are benign, it’s not necessary to surgically remove them unless they are large and causing your pet discomfort. If your pet is under anesthesia for another procedure, it may be practical to remove smaller lipomas at the same time.

Lipomas are often self-contained within a capsule, and surgical removal usually prevents their regrowth in a particular location. However, some lipomas may be infiltrative, meaning that they invade the muscle and other tissues. These masses are more difficult to remove with surgery alone. In these cases, radiation therapy may be necessary to prevent regrowth.