You don't
need to use circles in art (I don't quite a lot) but getting down basic shapes is always a good idea. That's where a lot of artists seem to go wrong; trying to do too many details too quickly.
Here's a photo of a wolf in about the same pose as your example [click]; See the differences?
As far as it goes, yours is pretty good! You have your own style developing, you just need to work on anatomy a bit.
Reference images are almost a
must when learning anatomy.
I'm assuming you reffed the Balto movies for quite some time? I know I made the same mistake, but reffing from the work of other artists - particularly a movie, usually only gets you into a hole.
Google is a decent place for refs, the only problem being not knowing who they belong to.
DeviantArt has many very good stock images of wolves (although dA's search feature seems rather glitched...).
GettyImages and Flickr are also very good places for ref images.
There's also WolfPhotography.com which is Monty Sloan's website and he takes fantastic wolf photos.
You don't need to copy a reference image exactly, that's a mistake a lot of people make, just grab 2-4 photos of the animal you want to draw in the pose you want to draw; a similar pose; a close up of a face; anything that will help you get to grips with the anatomy.
But you have a good start point!
Personally, I don't think your style looks much like Balto-style buuut that's a problem here; everyone seems to think every wolf drawing looks like Balto. XD
Have fun with learning anatomy, don't look at it as a chore; look at it as a fun challenge.
(Also, when I have time I can redline some of your art for you if you like? A redline often helps to see small mistakes more easily as it's directly on your art and not just looking at examples of anatomy. c: )