From: Equestrian and Horse | Horse Ailments
Bruises
This is where the underlying surface is damaged. Bruising can occur from a kick or knock or from treading on an uneven surface and bruising the sole.
Symptoms
If the horse has been kicked there will often be swelling in the area along with a tenderness to touch.
If the sole of the foot has been bruised by treading on a sharp stone or uneven surface then the horse will show a reluctance to walk and/or a shortened stride with weight being kept off one foot in particular or discomfort in all four
Treatment.
Prevention