I noticed my mare has developed a weird lump on the back of her fetlock joint (on/near the Sesamoid bones?). While she is standing, it's hard, almost bone-like feeling, but when her foot is lifted, the mass has a slight 'squishy-ness' around it. There's no heat or swelling. It doesn't hurt her and she is sound on it. I am still lightly riding her, while riding I keep her legs wrapped or booted, and there hasn't been any problems... I'm just concerned as to what it may be. No one at the barn has any ideas; the farrier will be out Tuesday afternoon so I will ask him about it then, but still.... it's just weird. At first I thought she accidentally kicked herself, but it's been a week and there's no change. Then I thought freak-bone spur, but it's perfectly round and the 'texture' just doesn't seem right to be that. Anyone have any ideas? Pictures: [^^^The lump is rock hard, not puffy or bubbly.] * NOTE: Her pastern/fetlock isn't swollen (even though it looks to be in the pic) and yes, the farrier is coming out in a few days.