Common Dog Diseases: The Lipoma (Fatty Tumour)

You feel your dog and find a soft lump under the skin. Your first thought: tumour. In older dogs, a harmless lipoma is the most common explanation for such a lump. However, this is only confirmed after examination.

A lipoma is a benign accumulation of fat cells that forms encapsulated under the skin. They occur twice as often in older bitches as in males. Overweight dogs develop them 30% more frequently than those with a normal weight.

How do I recognise a lipoma in a dog?

Lipomas feel soft and movable. You can usually distinguish them clearly from the surrounding skin. They grow slowly; a typical lipoma increases by approximately 1–2 mm per month.

Typical locations are the chest, abdomen and inner thighs. However, they can occur anywhere. A dog usually does not notice a lipoma with a diameter of 2–3 cm. It becomes problematic at approximately 5 cm in diameter or if it rubs against joints.

Caution is advised for hard, rapidly growing lumps. These may indicate a liposarcoma, a malignant fatty tumour that forms metastases in 15% of cases.

When must a lipoma be surgically removed?

Surgery is necessary if the lipoma grows larger than 5 cm or restricts movement. This also applies if it rubs against joints or if the dog shows signs of pain.

Infiltrative lipomas are a special case. They grow between muscles and can even reach bones. These must always be removed as they are difficult to delineate and often regrow. Recurrence occurs in approximately 20% of operated infiltrative lipomas.

Surgery costs range from 200 to 800 euros, depending on size and location. For dogs over 12 years old, vets weigh the anaesthesia risk against the benefits.

How do I distinguish dangerous lumps from harmless ones?

Harmless lipomas grow slowly and are soft and movable. It becomes dangerous with rapid growth (more than 1 cm per month), hard consistency or if the lump is fused to the underlying tissue.

Fine-needle aspiration provides clarity in 90% of cases. The vet inserts a thin needle into the lump and examines the cells under a microscope. This usually takes only a few minutes and is barely noticeable for the dog.

If findings are unclear, a biopsy follows. A small piece of tissue is removed and examined histologically.

Can lipomas be prevented?

There is no direct prevention. However, maintaining a normal weight reduces the risk by approximately one third. Overweight dogs develop not only more frequent but also larger lipomas.

Regular palpation aids early detection. A lipoma discovered at 2 cm in diameter is easier to operate on than one measuring 8 cm.

Does every lipoma require a vet visit?

Yes. Even though many lumps are harmless, only the vet can make a reliable distinction. Liposarcomas initially look like normal lipomas.

Do lipomas regrow after surgery?

For normal lipomas, this happens in approximately 10% of cases. Infiltrative lipomas return in 20% of cases as they are difficult to remove completely.

Can lipomas burst?

No. Lipomas are encapsulated and do not burst. If a lump breaks open, it is another condition, usually an abscess.