Environment

Remember "naturally healthy hooves are the result of the horse living a natural liestyle".
A healthy natural environemnt is key.

So what is a healthy natural environment?
This question can only really be answered by looking at the world in which the has horse evolved to live in.
Horses adapt to deal with different environments but the environments they have specialised in fall with in these peramiters:

In general horses are animals that dwell in:
Open grass land, prairie, tundra, moorland, desert conditions, some mountainous areas, open marshland areas, sparse forest and woodland.

By choice they choose open areas.
As prey animals they have been under attack from preditors for millions of years and are therefore hard wired to seek areas where they can see trouble apporaching. Open areas and elevated areas offer the best views.
These areas tend to have sparse vegetation, burnt by sun and wind. They therefore have become accustomed to travelling over vast areas to find enough forage.

Click here for more on Natural Diet.

Shelter.
These open areas offer very little shelter compared to dense woodland habitats.
People often note how horses can tend to favour trees rather than walled field shelters. It may not make sense to us but to them they are safer in the open and would rather bare the cold than compromised their view.

As prey animals living in open grass land their primary defense is to run. Long before trouble arrives they are on the move. The need to move is mirrored on several levels.

Movement.
By constantly being on the move they will be more difficult to track down than animals living in one spot. Take rabbits for example, who can always be found near their burrow, the burrow is their protection.
Horses dont have that protection and so they are always on the move.
Keeping their distance is their primary defense.
They have been on the move for millions of years. This state of constant movement and constant fitness has shaped their bodies, everything from their internal organs to their external physiology has been shaped by this need to move.
All of this enabled of course by the hoof and its specially developed self maintaining design. Hooves need this movment to become healthy and naturally shaped.

See the Natural Gait Complex.

This constant movement generates heat which keeps them warm. They use less callories walking than they do shivering.
Movement also helps to push blood around their bodies by the action of the muscles.This type of circulation support must have always been available, movement is a must.Spured on by the physical threat of preditors their bodies evolved and adapted to accommodate constant movment.Through this the herd developed a two tear social structure so they could move in an orderly manner with "protectors" at the front and at the back. Alfa's - leaders at the front (mare) and pushers at the back (stallion)Beta's - followers (in the middle)The one element of the natural environment that has shaped the horse more than any has been the presence of preditors. With out them there is little reason to move other than through the search for food. A natural environment should therefore include something spooky. So if your horse has an issue with something make it part of his environment!

Summary
Horses have evolved to live in a certain environment and therefore the following factors should be viewed as MUST HAVES not optional extras.Freedom to move at speed at any given time. Sparse vegatation spread over a large area to encourage movement.Company, a social group of alfa and beta horses who they can either protect or who can protect them and encourage them to move.Shelter, either natural or "quick exit" man made types.Clean unpoluted water preferabley at ground level.You can also include spooky areas to encourage more movement.