Hi Kara,
Dogs can be wonderful subjects for a photograph, in part because they really do show their emotions in a visible manner.
I like this photo in that you have managed to keep the background simple without going too high or too low with the camera angle.
That being said, it would have been good if you did not crop the dog's rear leg out of the frame… aside from the fact that the dog now seems to have an amputation, his leg leading out of the right hand side of the picture also leads viewers' eyes out of the frame. It is the equivalent of putting an exit sign on the side of your image.
Now, the only other problem I have with this picture is that the highlights are blown out on the dog's paw and muzzle.
Sadly, if you blow out the highlights of an image while shooting in JPEG mode there is no way you can really recover the highlight details afterwards in Photoshop.
The way to avoid this in the future is to keep an eye on either the histogram or the highlight warnings when reviewing an image. If you get the feeling an image is going to be too bright then either dial in some Exposure Compensation (-0.7 might have helped in this instance) or switch the camera into Manual Exposure mode and take control of the exposure that way.
Alternatively, if you captured this image in RAW mode you can just go back to the original file and make a new conversion.
Cheers,
Anthony