What are Fatty Tumors (Lipomas)?
A fatty tumor (or lipoma) in dogs is one of several different types of skin tumors. It is a slow-growing collection of fat cells usually found just under the skin. Fatty tumors are different than normal fat because they form lumps rather than a flat layer under the skin.
Like any tumor, fatty tumors are a form of cancer, but they are a benign form, which means they are a group of cells that multiply without normal control but do not travel through the body (metastasize) or invade surrounding tissue. Even though fatty tumors are not destructive to other cells, they can cause health problems by growing so large they press on internal organs. Depending on where they develop, fatty tumors can interfere with your dog's walking and movement. When fatty tumors interfere with movement, which is common when they grow between your dog's front leg and body wall (in the axilla), friction can wear through the skin and infections can develop.