Stroking the dog revels a small mass growing. These small or large masses need not be cancerous. There are many types of non-cancerous tumors that are found in dogs; like abscess, cyst, hematoma, hives or lipomas. Things to look for are if there is one odd mass or there are multiple growths. Also observe if the lump is rapidly growing, is warm or painful, is ulcerated or bleeding, is irregular in shape or is well attached to the tissues under the skin
