There are so many horses that will never be ridden barefoot depending on the horse (health, foot etc), the surface being ridden on and the surface of the pasture. 2 of my horses have been bare for over 5 years, another has never had shoe in her lifetime - 15 years. My horses are out on a nice soft squishy and sometimes wet pasture, then I ask them to ride down a dirt/partial gravel road. They will gimp on and off, some worse than others. Now, I can ride them around in the woods just fine as the surface is the same as their pasture. So I guess what Im trying to say is, if the surfaces are not equal, then the foot never gets used to it and will be tender. I have heard of people putting gravel in thier pasture or barn entries to get thier horses feet to toughen and get use to that type of surface. Think of it this way, if you walk on carpet all day in your house with no pain, why can't you walk down a gravel road with no pain? For me, I use hoof boots, usually only fronts. I never ever ride my horses down gravel without thier boots on, they would be miserable. I could be completely wrong and your horse is pastured on the same surface as you are riding. I will leave it to the experts to assess the hoof.