Lipoma – Benign Fatty Lump

Lipomas are one of the most common tumors found on dogs.

lipoma in armpit that has started growing back after surgery

They are benign which means they are NOT cancer.

  • What is a lipoma?
  • How is a lipoma diagnosed?
  • What is the treatment for lipomas?
  • What should you watch for?

What is a lipoma?

A lipoma is a benign fatty tumor. Generally they have a smooth round or oblong shape. When pressed they feel firm, almost elastic, are moveable and not painful; they do not feel hard.

The tumor is composed of mature fat cells with some fibrous tissue.

They are usually found just under the skin, predominantly on the belly and upper legs. Another area where they are frequently found is in the arm pit.

Lipomas grow slowly; although over time they can grow to be quite large.

Though lipomas are most common in overweight female dogs, they can occur in any dog. As a dog ages the likelihood of developing a lipoma increases. Most old dogs will eventually develop at least one lipoma.

Once a dog has one lipoma is it quite likely that they will develop more.

How is a lipoma diagnosed?

There are several other types of tumor (which are cancerous) that can feel like a lipoma, so it is important any that lumps are checked.

The vet will do a needle aspirate. This involves inserting the needle of a sterile syringe into the lump. The vet will suck some cells from several areas within the lump into the syringe. This is not painful for the dog, and often they do not even seem to pay any attention.

The vets will put the cells on a slide and look at them under a microscope to determine whether the cells are fat cells.

What is the treatment for lipomas?

Usually lipomas will not be treated.

However, if the lipoma is interfering with any function of the dog they will be removed. For instance a large lipoma in the armpit may create a friction rub. (My dog had a lipoma in his mouth removed.)

Lipomas are also sometimes removed for cosmetic reasons, but most vets discourage this since it requires anesthesia and there is always a risk with surgery. Additionally, depending on the form of the lipoma it can be hard to remove all of the tumor, so often they will grow back.

If a dog is overweight the vet will suggest the dog lose weight.

What should you watch for?

If your dog has a lipoma it is likely that they will develop more. Always get new lumps checked to confirm they are lipomas (as stated above there are other tumors that feel like lipomas that are cancerous).

If a lipoma starts to grow quickly get it rechecked immediately.

In conculsion

Lipomas are non-cancerous fatty growths that are very common particularly in older dogs. (See background information about tumors – benign, precancerous and cancer) They should be checked by a vet to confirm that they are lipomas. Unless there is a reason to remove them, usually there is no treatment.

All new growths should be checked. Never assume a growth is a lipoma.


* In the image a lipoma was previously surgically removed from the armpit – the pale spots are the sites of the stitches. A lipoma in the mouth needed to be removed since if it grew very large it could have made eating and swallowing difficult, so this large lipoma in the armpit was excised at the same time.. In the case of lipma in the armpit it is likely that a little bit of the lipoma was not removed since it is slowly grwong back.