The usual prescription for hoof angle is to make the hoof angle and the pastern angle parallel to each other.
When we lower a horse’s heel, we will also move the fetlock joint forward and upward in space. This occurs because of the structural relation of the DDFT to P3 and the back of the cannon bone via the inferior check ligament. So if a horse’s hoof angle is broken forward, we can correct the alignment by lowering the heel. The opposite is true if the hoof angle is broken backward.