Most owners first notice a skin lump or bump on their dog while they are petting them. These lumps, more officially called skin masses, may be present under the skin or on top of the skin. Many masses located under the skin have normal appearing skin and fur covering them, so they are only noticed when they are stroked or brushed against.
Masses that are on the outside of the skin are more likely to be hairless, and may appear as a different color than your dog’s skin – commonly white, pink, or black. These masses can range from smooth to ulcerated to bumpy and wart-like.