Growing up my family's GSDs got chicken breasts, eggs, and yogurt mixed in with their kibble, but I can't really say I'd I noticed how it helped/harmed them at the time as I was younger.
My bf and I have a Heeler/lab mix who eats Natural Balance, and I mix in yogurt. I have seen the benefits of beneficial bacterias in lots of animals, so I am hoping it helps him too. He used to have horrible gas, but since being with us it has vanished. I would love to supplement his diet more as enrichment, as he is active, has beautiful gums/teeth, and a very soft coat.
The cats eat Before Grain, but they would laugh at me if I tried a raw diet with them.