From what I can see in the photos, could it be scar tissue? Is it hard or soft when you palpate it? If it's scar tissue you may be able to sweat some of it out if you get someone who's done it to help you or give you details on how to do it safely. I'm glad it's not causing him any lameness but I wonder if it may cause an arthritic condition later in his years. If you think that's a possibility, my suggestion would be to avoid shoeing and use boots when riding, be mindful of surfaces to limit damage from concussion. Simple factors, sometimes not costing a cent, can go a very long way toward lifelong soundness.
Noticing his feet, if you can have your farrier drop his heels and get him at a healthier hoof angle, as well as be sure his bars are also trimmed, it will go a long way to keeping those legs and the rest of him balanced and comfy too. If he appears a little sore at all after his heels are lowered, a product such as Absorbine gel to rub on the tendons a bit. I hope anything here is helpful to you for Poncho.
Editing to add, I am sure but from the photo he may have some high ringbone - getting those heels lowered and setting him up will help a great deal.
Last edited by DRichmond; 07-05-2012 at 08:25 PM.