A Primer On Lipomas

A lipoma is a soft, round, moveable lump or bump of fatty tissue under the skin.

Lipomas are very common in dogs and are seen occasionally in cats.

Because the dog tolerates the mass, they’re usually identified at a checkup or spotted by owners when petting or grooming their dogs. However, each new lump should be examined to ensure that it is a  lipoma and not a malignant growth.

Introduction

Lipomas are usually benign.

They grow slowly and stay in one place. Lipomas that tend to cause problems are the ones that are large, or that interfere with movement. (If the lipoma is in an area such as an armpit, it can hamper movement or become irritated by movement.)

Once a dog has had a lipoma, it is likely to develop others. Lipomas occur more often in middle-aged dogs and overweight female dogs but some younger dogs can get lipomas.

Dog breeds that are more likely to have these include cocker spaniels, dachshunds, poodles, and terriers.

How is it diagnosed

A fine needle aspirate (FNA), in which a thin needle is used for a quick in-clinic microscopic look at the lump’s cells, should be done for each lump. 

A biopsy may still be necessary if the results of the FNA are equivocal.

How is it treated

Lipomas can be removed surgically. However, if your dog’s lipoma is only a cosmetic issue, you may take a wait-and-watch approach. (We will check the lump on a regular basis to make sure it hasn’t changed.)

It has been our experience that the removal of most lipomas makes the patient feel better. 

The lipoma can be removed when your dog is scheduled for anesthesia for another issue. However, if the lipoma interferes with movement or it is so large it’s irritating or bothering your dog, we recommend that the surgery be scheduled sooner rather than later.

Infiltrative lipomas

Lipomas on muscles often infiltrate into the muscle and cause pain, reduced use of the muscle and lameness. These should always be removed and removed quickly to keep the function of the body as normal as possible.

Cancerous lipomas

Rarely, a lipoma can become cancerous. They affect the area around the original lipoma and can also metastasize (spread) to other areas of the body. These malignancies are called infiltrative lipomas.

Your veterinarian will need to take a biopsy for histopathology examination at a veterinary pathology center. Infiltrative lipomas are difficult to control. Treatment may require radiation and surgery. (Chemotherapy does not work on infiltrative lipomas.) Infiltrative lipomas are fairly rare, but because of the difficulty in treatment, you should always have new fatty lumps checked by your veterinarian.

Masses that mimic lipomas

Cysts, Hives, Mast Cell Tumor, Fibrosarcoma, Hematoma, Abscess, Mammary Gland Tumor, etc., (may all look and feel like a lipoma)

Related articles:
Fatty Tumors in Dogs: If It’s Got To Be A Lump, Let It Be Lipoma

Further reading:
Fatty Skin Tumors in Dogs

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