I tend to be harsh on these kind of things, so don't think of it the wrong way.
Ok, the first thing I saw about this was the muzzle, its unnecessarily long and the lower jowl does not seem to match up with the main part of the muzzle. It's better to trim it down and give more definition on height and length.
The paws somewhat bother me as well, and so do the legs. The leg that is bending does not seem to have a joint, it just wrap around the chest and continues on the bone. It is also a strange angle you put the leg in, and when people over lap the arms on any sort of way, it either at the 'wrist' of the canine,like a cross, or the paws just lightly overlap without the other joints interacting. The paws need more definition on their part, and they need to be flat, then point up more towards the end.
The neck is over stretched, and the shoulder seem farther back then it should be. A little fact is that dogs don't have a chest, its just a imitation for the fur and extra skin. So it is better to place the shoulders first and give the skin and fur its part.This also caught my eye, the back legs seem to be forced back, due to the sticking out, and I knew that you were trying to make them stand straight, but they look distorted and painstaking. Just roll them forward and that is about it.
Sorry if I rambled on or hurt your feelings, it just I want to help you, and that is all
Thank you. I'd like to justify a few aspects here.
My choice in art programs is very limited, and the one I use for lineart always automatically curves my angles, making paws very difficult to draw. I can't shut off this option. I admit I often give up and lazily draw them in awkward angles after many tries, which ruins whatever anatomy streak I'm on. Joints are difficult for me to show in digital art.
As for the nose and chest, the character here is a Silken Windhound. This breed of dog is a sighthound -- it has a dolichocephalic skull, and a very large chest. I tried to portray that here, but sighthounds are difficult for me to draw when it isn't a profile view.
In other words, my anatomy sucks. xD That's why I try to get better all the time.
Thanks for the critique.