Navicular is an innocent bystander. Quite often a horse will be sore in center of the frog but have a clean x-ray.  This is called navicular syndrome. Research has shown this is most often soft tissue damage. I believe this is caused by under run heels combined with contracted heels.

This I think is caused by shoeing with too small of shoes and the old 'long toe, low heel'.
This way of shoeing does not properly support the elastic parts of the foot which is for shock absorption.

If you look at these feet, the one on left has very little digital cushion. The one on right has way more depth to it. The one on left has under run heels. The one on right dose not. Thus THE DIFFERENCE!

This picture shows a navicular bone with bone spurs on both sides of the navicular bone. Even though this horse has true navicular with proper balance we have been able to keep him sound for 7 years.  Refer to Grey and to [Henry still to come]. I believe that if we keep these horses balanced properly they can be maintained indefinitely.

I'm not saying all navicular horses can be helped. But if we can help some, it is worth it. Proper balance simply helps most horses.
                                                           Grey with balanced foot.

Henry first came to me the end of June 2003.He had been to Okotoks vet clinic.
He was diagnosed with navicular.He had bone spurs on both sides of his navicular, on both front feet.The prognosis was not good .They told Sue that she might get one more year out of him.Henry had severely under run heels,long toes as well as contracted heels.His frog was almost nonexistent.
                                                     Right front with  low angle.
Left front with low angle.

                                                            This shows navicular spurs.
                                  This is a xray from Dec 4  2008 you can see there is no change.
Henry was at a 45% angle. Witch is lethal to a horse .He also had way to small shoes on turned in at the heels . The first time I put shoes on him I put a 6 % wedge on him and put the heel back under his cannon bone where it should be.I used a wedge pad with sole support to get his frog working again.Henry showed improvement right away.The first challenge was to get his heel back under his cannon bone where it belongs. 
Once this was done I slowly started taking the wedges off till he was just in a shoe.We had Henry re. xrayed in Dec 2008 there was no change from his 2003 xrays.This goes to show proper balance can make a big difference.Henry is still going today March 2011.

                                              This xray shows proper alignment of bone column.