Well..you could look under his hoof & try to see anything unusual. Feel for heat on both hooves, typically if there's heat, there's swelling inside somewhere. My mare abscessed last summer, & I could see ANYTHING or feel an abnormal amount of heat. The vet misdiagnosed her with laminitis (he wasn't used to large animals), but gave her a shot of antibiotics. The next day, the abscess had ruptured through the top of her hoof. I soaked it in warm water & epsom salts, and about a week later, she was perfectly sound.