Below is the photo I was using for reference. I printed it out, then sketched the changes I'd need to make -- primarily, correcting the way the camera had "shrunk" her rear end. Copying verbatim from photos rarely makes for good art, and camera distortion is one big reason why not.
In the photo, her tail was tucked underneath her so you could barely see it. I pulled it forward to show that adorable little Greyhound tail-curl at the end. And I thought I was done, until Josephine Geiger said, "But what's she looking at? Put an ant in there!"
I groaned, but she was right. We needed to see what had caught Louise's eye. The dog's expression and winglike ears made me think of a butterfly, so that's what I went with. Just a small one -- but enough to emphasize Louise's charming, lively character.