Lipomas in Dogs (Fatty Tumors)

Lipomas that appear in our dogs are common masses associated with certain causes. They can be a cause for concern, since some reach a considerable size. Not all are harmful, and it's not always necessary to remove them.

Let's take a detailed look at everything related to lipomas appearing in dogs. What causes them, symptoms that should worry us, and what to do if we find one.

What Is a Lipoma?

Lipomas are common benign tumors or masses of mesenchymal origin, containing adipocytes (fat tissue cells) inside. They're often not clinically notable, since they cause hardly any symptoms besides the appearance of the mass itself. Normally, since they're noticeable masses, they tend to alarm owners.

Lipomas are usually rounded masses, which, if found in the subcutaneous tissue (the fat layer under the skin), can be "moved" fairly easily, clearly showing their boundaries and shape. This, generally, is a characteristic that the mass is benign (in this and other tumors).

Why Do Lipomas Appear on My Dog's Body?

Despite evidence showing a fairly frequent occurrence of lipomas in dogs, there's very little published evidence on the risk factors that tend to cause lipomas. It's been suggested that older age, and overweight dogs, carry a higher risk.

Every breed can be prone to developing lipomas. However, according to a study conducted in the United Kingdom, the breeds diagnosed most often were the Weimaraner (7.84%), Pinscher (6.96%), German Pointer (5.23%), Springer Spaniel (5.19%), and Labrador Retriever (5.15%).

Neutered males and spayed females carry a higher risk than intact dogs. Purebred dogs and heavier individuals were also more likely to be diagnosed in that study.

What Symptoms Does a Canine Lipoma Show?

As described above, symptoms are usually limited to the presence of a rounded, painless fatty mass that produces no clinical signs. That said, depending on its location, it may interfere with vital functions like eating, sleeping, limiting movement…

The large majority of lipomas are external and present with the symptoms mentioned above. However, there are lipomas, much less common, that occur in internal cavities in dogs such as the abdomen or thorax, producing varied symptoms depending on how severe the compression is due to proximity to the organs affected in each cavity.

In a study conducted by PD Mayhew and DJ Brockman, first published on February 10, 2006, it was confirmed that three dogs had a large intra-abdominal mass causing severe abdominal distension, two other dogs had a mass extending into the pelvic canal, compressing the colon and causing constipation, and one last dog had an intrathoracic mass causing intermittent coughing.

All the dogs had complete resolution of signs after surgical removal of these lipomas.

Diagnosis of Lipoma in Dogs

The vet will need to take a thorough history about the episode. We'll need to give them all the details we know, since these will be needed to form an initial idea. This includes: how long it's had it, how the tumor has progressed, the animal's age, etc.

Afterward, the vet will perform a general exam of the patient and the tumor itself. As for additional tests, although normally with this information the vet will already be fairly confident it's a lipoma, it can't be confirmed until a fine needle aspiration, or FNA, is done. In other words, contents from the mass will be aspirated after puncturing it and examined under a microscope.

Adipocytes will be visible, rounded, whitish cells. We'll then have the diagnosis.

What Treatment Does a Lipoma Need?

After confirming it's a lipoma, the first thing to do is measure its dimensions. At first glance, the vet may conclude that, if it doesn't bother the animal in performing any function, it needs to be monitored so it doesn't grow in size compared to the measurement taken.

However, if the lipoma starts growing in size, especially over a short period of time, it's best to remove it surgically. This will be a minor, simple surgery that shouldn't worry you (keeping in mind that any surgery and anesthesia carries some risk).

It's worth adding that there's a chance lipomas can come back some time after being removed.

This is a condition that shouldn't worry you, since it's easy to diagnose and treat, and in most cases produces no other sign besides the presence of a benign mass. However, we always recommend seeing a specialist so they can confirm it's a lipoma, since other tumors don't have as good a prognosis.