So before I say anything I am going to say that if this doesn't go away in the next day or two that I will take her into the vet. Circumstances are that I can't afford to bring my horses into the vet for every little thing. If she was actually acting lame I would have taken her in right away.
So yesterday Gypsy's left hind leg turned up swollen with heat. It starts after the hock and ends at the fetlock. Checking it out today it felt like a vein just below her hock was swollen feeling as well. Yesterday I figured she might have been stocked up so I got her moving for a bit and the swelling did go down to where there was more definition to the fetlock, but there was still heat. There is no reason for her to be stocked up, she is on a pasture with plenty of space to move about and is never locked in (Doesn't it usually happen when a horse is in a confined space with little movement?). There are no outward signs that would suggest that she has been kicked, scratched or cut recently (there was an older scratch but it has healed and scabbed over).
Any idea what this might be? Like I said, if it is still an issue tomorrow I will make a vet appointment, but in the mean time I don't see the problem with asking your opinions.