A lipoma on a dog looks like a round, soft lump sitting just under the skin. It feels squishy, almost like a small water balloon buried in the tissue, and it moves freely when you press on it or roll it between your fingers. The skin over a lipoma typically looks completely normal, with no redness, sores, or hair loss. Most lipomas range from marble-sized to tennis ball-sized, though some grow much larger over months or years.
How a Lipoma Feels and Moves
The hallmark of a lipoma is its soft, doughy texture. Unlike a firm mass that feels hard or fixed in place, a lipoma slides around under the skin when you nudge it. This mobility is one of the first things a vet checks during an exam. The lump has a smooth, rounded shape and sits in the fatty layer between the skin and the muscle underneath.
Lipomas are benign fatty tumors, essentially a clump of fat cells growing in a contained pocket. Because they’re made of the same tissue as the surrounding fat, they don’t feel dramatically different from normal body tissue. They’re just concentrated in one spot. The skin covering a lipoma stays normal in color and texture, and your dog’s fur grows over it without thinning or falling out. If you notice skin changes like redness, ulceration, or hair loss over a lump, that’s worth flagging to your vet because it suggests something other than a simple lipoma.
Where Lipomas Typically Show Up
Lipomas most commonly appear on the trunk, chest, and belly, though they can develop almost anywhere on the body. The areas where dogs carry the most subcutaneous fat tend to be the most frequent sites. You might find one along the ribcage, on the shoulder, near the armpit, or along the thigh. Some dogs develop a single lipoma, while others sprout several over time in different locations.
Which Dogs Get Them
A large-scale study by the Royal Veterinary College found that about 2% of all dogs develop at least one lipoma. Certain breeds carry a higher risk, including Weimaraners, Dobermann Pinschers, and German Pointers. The study also linked lipoma development to neutered status, higher body weight, and advancing age. Middle-aged and senior dogs are the most common patients, and overweight dogs are more likely to develop them than lean dogs of the same breed.
Growth Patterns to Watch
Lipomas are slow growers. Many take months or even years to reach a noticeable size, and some stop growing entirely after reaching a certain point. A lipoma that’s been sitting quietly at the same size for a year is behaving exactly as expected. If a lump suddenly doubles in size over a few weeks, or if it starts feeling firmer or more irregular, that change in behavior is more concerning than the size itself and warrants a vet visit.
Some lipomas do grow large enough to cause problems. In one documented case at the University of Guelph, an infiltrative lipoma measured over 14 inches across. Lipomas in certain locations, like the armpit or between the legs, can interfere with movement even at moderate sizes. In these cases, removal becomes practical rather than strictly medical.
What a Lipoma Can Be Confused With
Here’s the challenge: you can’t diagnose a lipoma just by looking at it or feeling it. Mast cell tumors, one of the most common skin cancers in dogs, can feel soft and squishy and sit right under the skin, perfectly mimicking a lipoma. A mast cell tumor might appear as a raised, soft lump that looks identical to a harmless fatty mass on the surface. The Merck Veterinary Manual specifically warns that visual signs alone cannot distinguish between the two.
This is why vets recommend a fine needle aspirate for any new lump. The procedure takes about 30 seconds: a small needle draws out a few cells, which are examined under a microscope. Fat cells from a lipoma look distinctly different from mast cells or other tumor types. Research published in Comparative Clinical Pathology found that fine needle aspirates correctly identified skin and subcutaneous masses about 89% of the time when compared against surgical biopsy results. For lipomas specifically, the accuracy was even higher. It’s a quick, inexpensive test that gives you a confident answer.
Infiltrative Lipomas: A Less Common Variant
Standard lipomas sit in a self-contained pocket and don’t invade surrounding tissues. Infiltrative lipomas are different. Instead of staying neatly encapsulated, they weave into the muscle fibers and connective tissue around them. From the outside, an infiltrative lipoma may look and feel identical to a regular one. The key difference only becomes apparent during surgery or on imaging, when the fatty tissue is found threading between muscle fibers with no clear boundaries.
Infiltrative lipomas are not cancerous, meaning they don’t spread to distant organs, but they’re locally aggressive and harder to remove completely. They tend to recur after surgery because their edges are difficult to define. If your vet suspects an infiltrative lipoma based on location or imaging, they may recommend wider surgical margins or advanced imaging before operating.
When Removal Makes Sense
Most lipomas don’t need to be removed. If the lump has been confirmed as a lipoma through a needle aspirate, is growing slowly or not at all, and isn’t bothering your dog, monitoring is the standard approach. Many vets will measure the lump at each visit and note any changes.
Removal becomes worth considering when a lipoma grows large enough to restrict movement, sits in a spot where it rubs or causes discomfort, or is growing faster than expected. Location matters more than size in many cases. A golf ball-sized lipoma in the armpit can cause more trouble than a grapefruit-sized one on the ribcage. Surgical removal of a standard lipoma is typically curative, with low rates of recurrence at the same site.