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As
dogs age, many develop lumps. Some are malignant growths that are
ultimately fatal. Others are benign. Luckily, the most common canine
tumour – the lipoma – is benign and rarely needs surgical removal.
Some breeds are more susceptible to lipomas than others. Labrador
Retrievers, Doberman Pinschers, Miniature Schnauzers, Cocker
Spaniels, Dachshunds and Weimaraners are at greater risk. However,
despite this breed predilection, lipomas are not believed to be
genetic in origin.
Lipomas form primarily in middle-aged to older dogs. Obese animals
are more likely to develop them compared to their lean counterparts,
and female dogs are at a higher risk than male dogs.
A
lipoma, as its name suggests, is composed of fatty tissue, but not
normal fat. The fat cells in a lipoma grow without regulation.
Because lipomas do not spread, they’re considered benign tumours.
Although most lipomas are solitary, many dogs develop more than one.
They can grow anywhere on the body, but are found mainly on the
lower abdomen and chest. The only time a lipoma causes a problem is
if it becomes large enough to cause functional difficulties. For
example, one growing inside the armpit can put pressure on the
foreleg, changing angulation, stressing joints and triggering
lameness.
Lipomas are characteristically round and soft except if they grow
under a muscle sheet, in which case they feel quite firm. It’s not
uncommon for other tumours to be mistaken for lipomas. Mast cell
tumours can feel just like lipomas, but unlike benign lipomas, mast
cell growths are aggressive, malignant tumours.
To
differentiate a lipoma from another tumour, your veterinarian
performs a fine-needle aspirate – inserts a needle into the growth,
extracts a few cells and spreads them on a slide. A pathologist
looks at the cells to determine the nature of the mass.
Even though lipomas typically grow slowly, they can become large
over a dog’s lifetime. The biggest one I have removed was located
beside the prepuce of a senior Labrador Retriever. It was the size
of a 10-pin bowling ball. Once removed, the dog, who was also
arthritic, was able to move with greater ease – not surprising,
since he had lost 14 pounds.
If
your dog develops a lipoma, should you have the tumour removed? Some
veterinarians prefer to monitor lipomas and remove them only if they
grow excessively large in an awkward place. Others believe it’s
better to remove them when they’re small because surgery is less
extensive.
Sidebar:
Can lipomas be prevented? Keeping a dog on the trim side
theoretically helps. As well, according to the book Manual of
Natural Veterinary Medicine, some Chinese herbs have reportedly
dissipated lipomas in people. The same might hold true for dogs.
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