The hoof is an amazing part of the horse. It plays such an important role to the health and well being of your horse. If you have an unexplained lameness look to the feet. It may show up in the back or hind end and be a mystery to your vet but in many cases, the origin is the feet. A hind end lameness can originate in the front feet. The hoof is easily remodeled by improper trimming and shoes.
When a horse wears a metal shoe, the hoof is peripheral loaded, meaning the weight of the horse is placed on the exterior hoof wall. There is much controversy to this subject but if you look to nature, the horse's hoof was meant to walk on the ground. When we place a shoe on the hoof, it interferes with the natural foot function and now the horse is not walking as intended. The frog must touch the ground in order to work properly. Shoes prevent this from happening.
Over time the hoof remodels itself to the metal shoe. In many cases, the heels become high, the toes long and the joints become stiff and painful. This changes the break over placing it too far out in front therefore altering the way your horse travels which puts extra stress on the joints and spine. When you remove the shoe, the horse is sore footed. The shoe goes back on to keep the horse comfortable yet the shoe is reason why the horse is tender-footed. The horse appears more comfortable with the shoe on because the horse cannot feel the ground the foot is supposed to be walking on. Without the shoes, now all of a sudden the horse can feel the ground as a result they are sore because the hoof mechanisms have been damaged.
It takes time and proper trimming to re-shape the hoof and restore the proper circulation so it can start to perform as nature intended. During this remodeling stage the horse will have periods of discomfort and perhaps cannot be ridden. Most of us don't want to miss our days of riding so we keep the shoes on the horse and continue to ride them. If you choose this path, eventually your horse will experience some disability such as ringbone, arthritis, back and joint problems. These problems could mean the end of your horses' soundness.
To avoid reaching a point of destruction, please consult with a hoof care practitioner who can help you to rule out possible problems. Finding the right person can be as difficult as finding a needle in a haystack. There are so many differences of opinion in regards to how the hoof should be trimmed or treated that as a horse owner it is easy to be confused, not knowing who to trust. The more you can educate yourself about the hoof, the easier this job can be.
What I find fascinating is the hoof responds much like a plant. If you put a plant in a pot that is too small for it, eventually it becomes root bound and grows funny, or parts of it start to die since it can no longer receive the nutrients it needs to grow strong. The same thing happens to the hoof if it is trimmed wrong or forced to walk on metal shoes. The change does not show up right away, but it will within a year or longer if not corrected.
On the positive note with correct trimming, exercise and diet, the hoof can grow out and be reshaped within the limitations of the natural conformation and the extent of permanent damage. During the growth process, the circulation is slowly restored to the hoof and all of it's inner workings. This slowly allows for a detoxification process or healing to take place. Give it time. It can take over a year to remodel the hoof, depending on the severity of the problem.