Chocolate~Complete

I've finally completed Chocolate, the Great Dane. I'm just not sure if the background is complete. As this is basically a full length portrait of this dog, I didn't want to create any detail in the background but I had to find a way to ground him. I used various washes of my original palette (FUB, burnt sienna and cobalt blue deep), applying them at different angles to give a faint impression of backdrop and floor. The reference photo showed the light coming from above which didn't leave many shadows and highlights to work with. As I look at this my instincts are telling me I need to bring in a dark value somewhere to make the dog better relate to the background. I'm just not sure where to place it yet. I've printed out a few copies and experimented with different options but I think at this point I need to set Chocolate aside for a few days until I have an epiphany.