After I grabbed a few shots of Robin running with Treasure, I turned around and watched Treasure walk down the beach:
And then tried to get a couple of the two of them walking together:
I tried converting that last photo in black-and-white and cropping around just their footprints:
I still don't have the footprint shot I want just yet. But it'll come one day.
(Shot with the Nikon D300 using the 18-200mm zoom; shutter-priority mode with shutter set to 1/1000 second (mistake!) and aperture set to f/14, f/16, f/8, and f/8 respectively at ISO 800; sunny white balance; SB-800 used as fill-flash; shot in RAW.)