This is, all in all, a very nice piece. The concept is original and the actual art was well done.
The pose is great, but has minor flaws. The pony/zebra(?)'s swishing tail was well done and it really does look like (s)he's leaning her/his shoulder on the door but his/her head is held at an awkward angle to it. It's turned too far to the viewer's left and would intersect the door. At the creature's chest, as well, it's hard to tell where the leg stops and the belly begins.
The general effect of this comes clearly across as worried, and the facial expression is excellently subtle. My little nitpicks with this are that the general color scheme seems a little bright (the gold, in particular) for the atmosphere you seem to be trying to convey and the light source on the jacket seems a bit ambiguous. The shine comes from the left, the right, the top, whereas in the rest of the picture it comes from the center.
These problems are all very little, and it is a great drawing overall.