Hard lump on back of front fetlock?

[huskydamage]

so I'm wondering...what the hell is this??? The lump is stone cold and rock hard, she doesn't mind me touching it and seems not bothered at all. She is 22 so does have lumps and bumps, but I've not seen a weird rock hard one like this before. It's central on the back of the fetlock, does not move and feels like bone. I did ride today as she's not lame at all, but as it didn't go down after (as her windgalls usually do) I do not feel comfortable riding again without knowing what it is. (She is the sort who doesn't show me something hurts until it's too late!) Will talk to vet later but wondering if anyone has any ideas/seen similar?

 

[Ronalda]

Looks like either a windgall of the proximal tendon sheath where the distension has evolved into synovial tissue and therefore not drained as it would if remained fluid.

Although there is no lameness it maybe sesamoiditis where the insertion of the suspensory ligament branch has pulled against the sesamoid bones due to over extension and caused swelling and bone growth. If you look from behind the fetlock is the lump located centrally or over to one side (ie both or one sesamoid bone). Raise the leg off the ground, so the suspensory ligament is slack and palpate with fingers along the ligament down the leg to the sesamoid on both sides; is there local heat or a reaction?

 

[huskydamage]

Hoping it is a windgall ! :s It is ever so slighty to the right, still seems fine this morn- but will have a go picking up the leg and investigate further this eve