what you are animating is a trot. The dog would have more up and down motion for a trot. You need to look at a normal walk gait for a dog. the front legs and back legs are not sancronized like you animated here.
I think the animation is very good. I like how he seems to move around like an actual dog, which makes it look realistic. For future reference, though, I don't see the points of all the lines on his back leg (I see this is supposed to be a shadow) ,just shade it.