Part of the fun for me in photographing dogs is to capture images which portray the personality of the animal. When I am photographing for a rescue, that's kind of difficult because I don't really or thoroughly know the dog (haven't spent much time with it). By taking a few minutes to "welcome" or "play" with the dog, you get a sense of their personality.
When I photograph them, I use the continuous shooting setting on my camera and take quite a few images. This method allows me to capture the dog's personality.
This image of "Done Yet?" was taken at Noah's 5th birthday party. Though he's a patient dog, and lovingly cooperates when I photograph, he does get this expression of "are you done yet?"