Most breeds of dog have 16 toes, as each paw has four toes. Certain breeds can have an additional toe on each hind foot, called a dewclaw. Dewclaws appear on dog breeds that were historically used for guarding flocks, such as the Australian shepherd and the Rottweiler.
The Great Pyrenees is another exception; it can have up to six toes on each hind paw. The presence of an additional toe may be an evolutionary reversion in dogs. The dewclaw, which is attached either by flesh or by bone, can be surgically removed if it presents a problem for the dog's mobility.