My horse has a more pronounced "lump" on the back of his right hind fetlock than his left - I say "more pronounced" because I think that you can see a bit of a bump on most normal horses anyways (it may be the annular ligament? I'm not sure) - in his case, the right hind is about twice the size of the left. On top of that, he tends to get puffy right above the lump (looks like windpuffs), and his entire right hind leg tends to be warm (including the hoof).

The lump is hard, appears to be non-painful to palpation, and doesn't give off significantly more heat than the rest of that leg (the whole leg is warm).

I tried to take some pics, but the shadows were working against me! lol

Here is his left hind (the one I'm not worried about), from this angle you can see the small lump which appears to be "normal":





The next two are of the right leg - if you make the pictures big and look past the shadows, you can see the more pronounced lump - I know they are bad pics







Has anyone seen something like this before?

I have called the vet, but she said that without lameness and pain, it's probably OK. If I get really worried, she'll come out of course, but it's a $100 call fee plus whatever they do when they're here, so of course I'd like to save myself the money...