Dog fighting is a type of blood sport that turns game and fighting dogs against each other in a physical fight, often to the death, for the purposes of gambling or entertainment to the spectators. In rural areas, fights are often staged in barns or outdoor pits; in urban areas, fights are often staged in garages, basements, warehouses, alleyways, abandoned buildings, neighborhood playgrounds, or in the streets. Dog fights usually last until one dog is declared a winner, which occurs when one dog fails to scratch, dies, or jumps out of the pit. Sometimes dog fights end without declaring a winner; for instance, the dog's owner may call the fight.

A blood sport or bloodsport is a category of sport or entertainment that involves bloodshed. Common examples of the former include combat sports such as cockfighting and dog fighting, and some forms of hunting and fishing. Activities characterized as blood sports, but involving only human participants, include the ancient Roman gladiatorial games.