Snowdoll, in the meantime, has suffered from on and off again diarrhea and it took us forever to find a food that is good for her. Finally, she is eating something that agrees with her sensitive tummy and Rob and I have decided that we are switching Romanov to the same food because obviously, whatever his age may be, he is not happy with the mature dog food.
What we are going to feed them (along with the usual treats and extras) is Eukanuba's Naturally Wild North Atlantic Salmon & Rice. This seems the most obvious choice because in the wild their diet would be more likely to include fatty fish like salmon and with Snowdoll's ongoing need for rice to keep things good for her we saw no reason not to make the change.
I'm hoping we'll soon see a more slender Romanov. I'm sorry we ever made the switch and I doubt that when it's Snowdoll's turn to be labeled "mature" we will be so hasty in changing her diet.