This is the Left Front foot, shoes just removed, and has sheared heels.
This type of pathology can be caused when the feet are trimmed unlevel, and the shoes fix the structures and tissues in this position. It is most easily dealt with by allowing the horse to be barefoot, where the foot can be trimmed in such a way to allow the imbalances to correct themselves.
While the inside and outside walls are the same in length, the inside is higher, starting further up the leg (point B). The hairline (green line) is steeper on the outside than the inside. The connective tissue inside has been held in place pathologically and has adapted to this orientation. To make a change towards a healthier foot, the inside (higher) wall is trimmed shorter. As the horse places weight on the leg it allows point B to move down (from the red line to the yellow line), and eventually the tissues readapt to their natural position.
Three months later
The inside and outside heel points and wall weightbearing points (in red) are beginning to line up (as demonstrated by the light blue dashed line). The hairline (in green) has begun to adopt a healthier appearance with more similar angles comparing inside to outside, as well as becoming more rounded or curved in appearance, reflecting the improving health of the inner tissues.