Lipoma in Dogs
Lipomas are subcutaneous (underneath the skin) masses or tumors that develop commonly in dogs. They are usually soft, with limited mobility under the skin. The overlying skin is usually not affected. Over time they can grow larger and can impede movement if they are located between the legs or low on the chest. Most dogs that develop a lipoma will develop multiple tumors. But, it is important to recognize that additional masses do not necessarily indicate malignancy or metastasis. Since other cutaneous masses may appear similar to lipomas, it is recommended that every mass be checked individually.
Another sub-classification of benign lipomas are infiltrative lipomas. These typically invade locally into muscle tissue and fascia and may need to be removed.
Liposarcomas, on the other hand, are malignant and can spread (metastasize) to the lungs, bone and other organs. These tumors are rare, but are indicative of the importance of examining all subcutaneous masses respectively.
Most lipomas feel soft and movable under the skin. They usually do not make pets uncomfortable unless they are in a location where normal movement is disrupted, like in the axillary region under the front leg. Often they are located on the belly or trunk, but can be anywhere on the dog’s body. Most dogs with one lipoma will eventually develop several.
Your veterinarian will do a complete physical exam, checking for all palpable masses. A fine needle aspirate will indicate whether the mass is a benign lipoma, or whether it is a more worrisome masses that is mimicking a lipoma. If the aspirate is inconclusive, surgical removal and histopathology may be necessary to arrive at a clear diagnosis.
Infiltrative lipomas may require a computed tomography (CT) or magnetic resonance imaging (MRI) to adequately understand the mass and tissue location. This can be important information for the surgeon to decide how much of the mass can be removed and what approach needs to be employed for surgery.