Lipomas are common in dogs
My Dog Has a Lipoma. Now What?
Lipomas are relatively common tumors in dogs that can arise from fatty tissue anywhere in the body. Dachshunds, cocker spaniels, poodles, and terriers seem to be especially predisposed to these, but dogs of any size can come down with them as they get older. Lipomas present as soft, fluctuant round masses that are adhered tightly to surrounding tissue.
As a rule, lipomas rarely pose a health risk to a dog and surgical removal is usually not recommended, since they tend to recur after surgery and elsewhere on the body. However, if they grow very large and mechanically interfere with the limbs, removal may be necessary. Fortunately, the malignant form of fatty tumors, liposarcomas, are rare in dogs.
All dogs that develop lipomas should have their thyroid function checked. Also, putting a dog on a fat-reduction (weight loss) program will help shrink the size of the lipomas for obvious reasons.
Sometimes, lipomas can form within the body cavities from fat adhered to body organs or from membranes lining the cavities. These can form large space-occupying masses that can impinges on surrounding organs. Here's a picture of one lipoma that was removed from the abdomen of a Labrador retriever (no, not from the dog in the picture..he was there to give you a size perspective).
Needless to say, the Lab felt much better (and lighter) after surgery!