The fetlock is formed by the joint between the canon bone
and the longer pastern
bone. At the back of the fetlock lies a small bone called the sesamoid. Occasionally, you may hear the fetlock joint referred to as the pastern joint or ankle. This joint although it may appear so, is not actually analogous to the human ankle.
Pronunciation: fet lawk
She was alarmed when she felt heat and swelling in the fetlock joint after jumping her horse.