Why horses in transition are "sore on gravel"

The transition from shod to barefoot is not about "toughening up" the sole. It is not the sole that is sore, it's the corium -- a layer of living tissue on the bottom of the coffin bone that grows the sole. Iodine or other drying treatments do not speak to the actual problem. Putting gravel in the horse's turnout to "toughen the feet" will work against you; wait until after transition is completed

When we have a stretched white line -- due to the lack of nutrition in a shod hoof, or due to the mechanical forces of a flare -- the coffin bone sinks away from the hoof wall and presses down onto the sole corium. The corium gets inflamed by the constant pressure of the bone. When the horse walks on gravel or rocks, it hurts. It's like when you have an inflamed finger; you'd rather not bump into sharp corners with it.

Below is a cross-section diagram through a hoof with a tight white line (left), and a hoof with a stretched white line (right). Notice that the coffin bone actually hangs lower inside the hoof capsule; it sits down onto the sole corium and inflames it; and the sole is flatter.

10_transition_1_inflamed_corium

The horse will not go sound-on-gravel (or other hard, uneven terrain) until the white line has healed and tightened up, and the coffin bone is held firmly up inside the hoof wall. This should generally happen within a year, with a consistently renewed mustang roll.

Winter is a hard time for transition horses. Expect that your horse will be sore when the ground freezes, through the first and sometimes the second winter after pulling the shoes, even though he is sound on soft ground. You may need to provide boots for turnout on frozen ground.

Some transitioning horses go sore on deep sand or very soft arena footing. This is because the soft landing doesn't provide enough concussion to flex the hoof, so that there is reduced circulation and the feet become uncomfortably congested. The best solution I can suggest is to ride at least 10 minutes on firm ground, before and after the arena work, to get lots of circulation inside the hooves.

There are types if arena footing that are quite firm without being slippery. One kind used in my area is quarry screenings left over from making gravel. I would like to see us replace soft arenas with firm footing that gives the feet enough concussion. After all, for many of our horses, the arena is where their hooves get most of their work.

No hour of life is wasted that is spent in the saddle.  ~ Winston Churchill