Oh so much to talk about with this one!
Well I can easily see how you might be testing your ability on this one. Of which, in my opinion, you have succeeded.
First of all, I love how the first two panels seem so peaceful in comparison to the remaining four. You instantly catch suspicion on the second panel. Why hasn't the scene cut to the outside? Why did he pause? Then suddenly the answers rush in on you.
Which brings us to my second topic. Expressions. In response to the dog's call, you can see how alert/shocked the guards are easily. And the next panel is just priceless! Even the dimmest sighted people can see how rattled the poor mutt is there, being rushed upon by a hound that seems to be at least twice his size. Though i think in the last panel the faces can use a little more excitement but all the same, it is a very good piece in that department.
Thirdly, I love how the fifth panel seems to want to pop out of my screen! I can see that you drew every panel. Not just copied the background. Though its hard to see, if you look at the boulders in the first and second panel you can see them vary in size. Usually one thinks this is a mistake... i think its nice how you take the time to do every single panel. stroke by stroke.
And on that, I conclude my Critique.