Have him tested for metabolic syndrome. I have a handsome cremello warmblood whose dam had metabolic syndrome. We discovered it in her because she was walking short then foundered, thankfully not badly. She was getting barely any grain at the time, less than any of the other horses. When the gelding seemed a little off, walking gingerly, I had him tested and he also has it. Neither of these two can be left out on grass or they will founder. First cut hay only. No grain, just supplements. I give them smartpacks for feet, plus an ounce of California Trace twice a day. I have to worry about the same problem, and had to change farriers to get one that knew what they were doing. I can keep him barefoot almost always, and rarely glue ons in front if he needs the growth support.