A deviation from normal movement in terms of limb flight as seen from the front, the back or from the side. From the front and back a limb should move approximately in a sagittal plane: lateral or medial deviations are known as winging, brushing etc. From the side the flight of the limb depends on the gait in which the horse is moving: gait abnormalities that are observed from the side include forging and toe dragging. If limbs strike each other as a result of a gait abnormality this is known as interference.