I originally wasn't going to write a critique on this, but after looking at it for a while I felt like there were some things that needed to be pointed out.
I'll start off by saying that the detail you put into certain parts of this piece are absolutely astonishing, you really made the long, fluffy fur stand out on its own way, and the shading on it is pretty good, too!
Unfortunately, I have to say that I was actually quite disappointed with the other aspects of this picture. Obviously, your forte here the long fur as I already mentioned, but what about the rest of the picture? What about the tail? It could really use some more 'fluff' on it, it feels like you only focused on the neck of the wolf, to be honest, and the tail was just left out.
Moving onto anatomy now, I will say that most of it is actually pretty good! Now, what does 'bother' me a lilttle is that I feel like the ears are a bit too big for a wolf, considering they have fairly small and stubby ears, and their muzzle is pretty short, too (Compared to other canines, like Coyotes, for example) [ [link] , [link] , [link] ] The other thing I should mention is that the head is in an odd angle. The eye part looks like it's 'looking' back (to the background, obviously), but the rest of the head is looking sideways so overall it looks a bit 'off'. Maybe you should've tried doing it all on a side-way angle, or looking at a stock image/reference for the muzzle part.
Last but not least, the background. I personally feel like the blue-black transition is the sky is a bit too harsh, and you could've made it all a bit darker. Also, the snow looks rushed, and it seems like you didn't focus too much on it, either ):
Other than that, I don't really have anything else to say, I can't wait to see another piece of yours! The atmosphere here was really well done, and I'd love to see you improve even more!