It's OK to trim the hair if necessary; it's not OK to cut off the foot as you've done here. But neither is required in this case. Here is how I would crop this shot, in (because it happens to work best in this case) a standard 2:3 ratio:
I also did a little bit of levels on it to brighten it slightly, a local contrast enhancement (USM 10/50/0) to add a little pop, and converted to sRGB (very important for web images).
There's nothing wrong with cutting off body parts (but as you say, not at the joint!) if it's necessary or contributes to a stronger image. But there's no need to do it for this shot (which is a very nice one IMO).
Nill
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