In the last few weeks this has happened often, about 2 or 3 times a week and he has just started to refuse to pick up the canter lead on the right rein. Most of the time he will pick up the lead in front and disunite in behind. He is a reasonably lazy horse and is barefoot but have also noticed some squaring off of the back hooves and last night that he was dragging them slightly on the lunge. Not sure if this is related or if he is infact being lazy. I have spoken to a radiologist who suggested their maybe some cartilliage damage. He was a show pony and then did some dressage and very small abouts of jumping so their shouldnt be too much wear and tear. Has anyone had a smilar experience?