This riding school horse came in from the field with just a slight lameness. I took a look at him and at first there wasn't anything obvious to find. I then methodically applied pressure around the whole of his foot with hoof testers to find where the source of pain was. When I hit the right spot he sure as hell let me know! I scrapped around with my knife and although I couldn't see anything stuck in there to start with I could hear a scraping noise with something connecting with my knife. After some careful investigating I removed a thin shard of flint from his foot. It bled quite a lot which is good as it flushed out any dirt that went in with it. After a week of poulticing he never had any more problems with it.