At best we can only expect to manage the feet to minimize the founder damage and to maintain a reasonable level of comfort. That is the simplest solution. Any kind of shoe adds to the load on the wall. It is best to remove them. It is critical that the horse be provided with a large area of turn out on a 24 hour basis.
Exercise simulates circulation which promotes healing.
Next it is important to provide for positive drainage of the fluids building up under the wall and sole callous. Rasp away the hoof wall or cut gouges through the wall thickness exposing soft moist horney laminae adjacent to the sole abcess. Apply a poultice over this exposed laminae on a 24 hour basis for 4 to 7 days, until no more fluids are drawn out. You may not get there exactly on the first trimming. Do not trim away any sole callous around the toe.