Swollen Hock

[pixiebee]

My horse came in from the field today with a larger hock, no obvious heat an doesnt appear lame, didnt worry about me poking it, cant see any cuts/marks. She has been a bit grumpy with my gelding so wonder if she has been kicked?? I have put a pick of where the swelling is (borrowed pic from net) the swelling is actually quite hard?

 

[pixiebee]

forgot to add, the swelling basically fills in the bit that would be the narrow part of the hock (the bit on the outside where he goes in) is filled in, it does not extend beyond this point, looks more puffy than swollen as such?