First thing, if you're using Gimp, for outlines I'd recommend turning on Smooth Stroke and use sizes in a range of 1.0 - 5.0. Second thing, if you aren't, turn on layers. It gets a whole lot easier if you use them.
As for anatomy, it's pretty good. The snout to forehead transition isn't amazing if you're going for realism, but if you're pursuing your own style then that's fine. The position of the ears and mane is kind of odd and the mane itself is pretty off itself, so I recommend trying to fix that a bit.
To help you more, I'll need some information on what you currently use n' stuff, because I'm going off the background as indication of "it's probably gimp."
I hope this helped.