After talking further, she said it fell through because the girl wanted a "cheap expensive horse". The mare was apparently raced until she was seven, but is sound, other than having a bit of soreness in her front fetlock. The woman said it was found during a flexion test and that the vet said it might end up bothering her or it might not.. just to give her a supplement and that she might eventually need injections.
I really appreciated her honesty about it, so I do trust her opinion. She said she hasn't had the mare jumping yet, but is getting jumps this week from a friend. As of right now, the mare has been back in work for sixty days and hasn't showed any signs of soreness.
So, my question is, should soreness in the front fetlocks cause any real issues for jumping and potentially dressage? She'd still be on supplements and I'd likely get some liniment for after and before rides.