If a foot ulcer is not treated, it becomes more susceptible to infection. Infected foot ulcers can also develop abscesses (pockets of pus) which can spread the infection to the skin, cellulitis, or cause bone infection or gangrene (dead tissue due to poor circulation). These complications can worsen the overall condition of the foot and may result in amputation or serious infection. It is important to seek proper treatment for foot ulcers in order to avoid these potential risks.