I should have done this a couple of weeks ago, but hey-ho, better late than never. Here is the finished drawing. Although what you can't see here in this photo of the drawing is that I did add a subtle shadow beneath each dog to help ground them (thanks fellow Artpapians!). I was in a hurry to get the finished piece to the customer and didn't get a chance to take a photograph of the finished piece.
I found once I had drawn in the second dog, which is much darker, the golden retriever required some further darkening to help balance out the toning in the overall piece (I didn't want her to fade into insignificance!).
Another satisfied customer!