People remove horseshoes from horses after a while and replace them with new ones. So a loose horseshoe may not imply a dead horse or the show falling off. It may just mean that it's a little worn out, but still good for luck.
    The horseshoe above my front door, incidentaly, points up, to keep the luck in. There is no room for the devil to sit in it, anyway,there is a thing over the door(what is the opposite of a sill?) that the points are nearly touching; it would be very uncomfortable for the devil.