What is a cause for gangrene?

Dead tissue: Ischemic or dead tissue that is not getting enough blood supply for oxygen & nutrition to the site, maybe from combination of poor blood supply and infection., can result in gangene of tissue.

Two kinds: Dry gangrene is simply dead tissue. It could have been caused by freezing, burns, or a severe interruption of circulation with the necessary nutrients and oxygen wet gangrene is a type of infection of the dead tissue by a very specific bacteria. This bacteria produces a variety of toxins which can spread, cause more dead tissue (necrosis) and kill you. This is an emergency.

Causes of Gangrene: There are 2 basic types of gangrene...Dry and wet. Dry gangrene is caused by the lack of local blood flow, usually from arteriosclerosis. Wet gangrene can also start off as dry gangrene, but then gets infected, sometimes with very aggressive, flesh-eating bacteria.