slightly thick leg

[Marilyn]

I'm sure I'm just being worried for nothing but this morning my mare has a slightly thick hind leg...we have just moved her into a field with a three year old who is determined to make her pay with him and this morning she was dashing round like an idiot to teach him a lesson...so i'm sure it's just a slight twist or something. The thickness is just in the tendon area...any ideas?

 

[Tia]

Is she lame? Is her leg hot and puffy? How much swelling is there and how extreme is it?

 

[Marilyn]

not lame, warm at worst, slight swelling...literally just a bit thick, stiff definition where tendon and cannon bone are