Several types of skin tumors can affect dogs. Most are benign. However, some skin tumors are malignant.
The benign tumors are usually slow growing, soft, and free moving; meaning that you can grasp them and move them around under the skin. Benign tumors include: skin tags, warts, moles, and lipomas. Skin tags, warts, and moles look similar to the ones we get. They are unsightly, but harmless. Lipomas are fatty tumors that are very slow growing and soft. Lipomas are very common in older, overweight dogs. They typically don’t cause any problems unless they are located in an area that restricts movement; such as under a front limb.
The most common malignant tumors found under the skin are Mast Cell Tumors and Osteosarcomas. Both of these tumors are usually fast growing, hard, and attached to the tissue under the skin.
Mast Cell tumors are very common and can be found in all breeds. However, Boxers, Beagles, and Boston Terriers are the breeds most commonly affected. These tumors can be found anywhere on the body, but are often located on the limbs. They can change shape and size very rapidly. Mast Cell tumors are made up of cells the body uses to respond to inflammation and allergies. These tumors can release high amounts of these cells into the dog’s body and cause damage to the internal organs. Some Mast Cell tumors remain localized, but others can metastasize to other regions of the body. It is very important to have Mast Cell tumors removed and sent for a biopsy to determine the malignancy and risk to the dog’s overall health.
Osteosarcomas are bone tumors. These tumors are highly malignant. They are most commonly seen at the elbow, wrist, or shoulder. However, any bone can be affected. Limping on the affected limb is usually the first symptom. However, often times the tumor isn’t noticed until it becomes visible. At the point when it is visible, there is a 90% chance it has already metastasized to another area of the body, usually the lungs. Treatment of osteosarcoma is very aggressive and usually involves chemotherapy or radiation.
In conclusion, although there are many types of skin tumors that are benign, it is important to have all tumors examined by your veterinarian, so that treatment of malignant tumors can begin as early as possible.