HI, I will leave this open. The steriods are an issue. THIS problem has haunted owners and Vets for ions. Race horse people have two minds. Race still they break down, shot them up, race them until it is permanent, sell them to a kind compasionate owner that suffers emotional trying to save the horse. Most likly the former owner (over)used steriods and created this problem. This is no different in human that have long bone tendon calcification because of over steriod use intentionally or not. Double hip replacments and knee replacements are the end result. However, your Vet and farrier are right. Each time the tendon scraps the bone, it gets inflames. However, the injectable at the end of the article suggests a synovial fluid injection that may give relief for 2-4 weeks at a time with Sarapin and another med. You may not even have that available to you. Also your horse could be worse than I know because I can not see him. However, the question of lameness seems to also be an issue, they say Yes, you say no. This needs to be determined so you horse can try a treatment of not. I leave ths open to any other Vet that wishes to comment. I wish you the best. A racehorse Vet would be your best choice.