Over the years I have been amazed at the variation I have seen of the carpal (wrist) joint in greyhounds. Since the carpal joint acts as a shock absorber for the foot, it is very important that it is built correctly.
The correct leg (below) has a slight bend at the carpus.
An overextended carpal joint (below) is very weak and leads to breakdown of the joint.
An upright carpal joint (one with no bend) can lead to a lot of toe injuries since there is no give to thejoint. I have had one dog that had carpal joints like this and he lived in splints and casts through much of his life due to toe injuries. Both of the pictures below depict upright carpal joints.
Probably the worst carpal joint position is one that is overflexed. It is extremely rare and extremely unsound and incorrect. A dog with a wrist like this (below) can never be functional.
In addition to carpal joint angulation, foot position is also important. Most people believe that the correct foot position is straight forward as in the picture below.
Open field coursing folk would rather have a slight toe-out position (below) as they feel the dog can turn faster and easier thus staying with the hare.
Certainly a "pigeon toed" or "toed-in" front is not functional. A dog with this foot position, such as the one below, could not handle the stress of running.
In summary, a greyhound is a powerful breed that puts incredible strain on its legs and feet. A correct carpal joint and foot position is important to keeping the dog sound through the years.