Hi Julie

Your images are great. Just a couple of suggestions. Since your muslin is so big have you thought of draping it over the box or stand that you sit the dogs. It would make a more seamless background.
Also have you thought of putting the background light on the ground behind the dogs pointing up. I would just guess that your MAIN would be enough of a hairlight by itself. Mine has a slave built in so is triggered by the Main. Just some thoughts.
www.bsvirginian.smugmug.com