Nice model there!
If I can say just a small thing... I think that you should add more definition to the shoulders of the front legs. Look at the shoulders of horses, dogs, etc: there are muscles that bulk only around the shoulder joint itself, and muscles that go from the shoulder to the elbow joint. In your model, it looks like there is just 1 large and smooth set of muscles going directly from the body to the elbow.
Did I make any sense?