Hmmm... if you want my advice, I have a few suggestions. If you really want it to look fierce, maybe add some drool to the snarl, and make the tail erect instead of droopy so it matches that of an angry wolf or other canine. The same can be said about making it's head a bit lower than it's torso. Ears should probably be pointed backwards for aggressiveness rather than neutral-outward. Make the neck-fur stand out so it looks like it's a threat. If you're planning on coloring, I'd suggest some dramatic shading on the far side of it's face so it looks more imposing.
That's about all the advice I have to give, otherwise it looks really great! Better than I would've drawn, anyway. Good job! ^w^