A foreign body penetrating into the foot is a fairly common, and potentially life-threatening problem. Nails and screws are commonly scattered around construction areas, and horses step on them and drive them through the ground surface of the hoof. Nail punctures are potentially serious because the critical structures of the lower limb lie within the hoof. The severity of the problem depends on what structures are penetrated.

Occasionally a shallow, simple nail puncture results in no problems once removed. Sometimes the object does not involve critical structures but results in a sub-solar abscess that, once drained, causes no long term complications. In contrast, sometimes the object may penetrate bone, joint, bursa or tendon sheath resulting in massive infection, severe lameness, and life-threatening complications. The absence or degree of lameness is a helpful indicator of severity and infection.

Typically these injuries are discovered when you pick up your horse's foot and see the offending object.