Any ideas what this is?

[redmimosa]

Ok, so this is a five year old mare, that I bought cheaply unhandled (and hence unvetted). She appeared to have what was a windgall type swelling on one foreleg. I have her about four months, she is now broken and riding and never shown any sign of lameness. The other day I clipped her legs to better treat a bit of mud fever/cracked heels and also as we have a showing clinic coming up and the legs were quite hairy!
Upon clipping the leg in question it became obvious that the windgall was not really a windgall but a bump which for all the world feels like scar tissue. Any ideas what could cause such a bump in this location. It looks quite unsightly now that the leg is clipped as she has very fine pins! It doesn't seem to bother her when you poke and prod but I'd like to know its cause!!!

Any ideas welcome

 

[ILuvCowparsely]

cant help but notice the rings in her hooves!!!

 

[redmimosa]

yes, pretty sure they are from the change in nutrition when i bought her as they are at about four months growth!? ie from the field with no food to proper diet!