The following is from the Great Dane Standard:
The hindquarters shall be strong, broad, muscular and well angulated, with well let down hocks. Seen from the rear, the hock joints appear to be perfectly straight, turned neither toward the inside nor toward the outside. The rear feet should be round and compact, with well-arched toes, neither toeing in nor out. The nails should be short, strong and as dark as possible, except they may be lighter in harlequins. Wolf claws are a serious fault.