Mine get Kirkland lamb & rice. I started Moose-dog on chicken & rice, but it didn't sit well with him, so I switched to the lamb & rice. He's been great on that for years, so I've never switched back. Bat-dog eats the same with no problem.
Have you looked at the quantity of food you're giving her? Bat-dog gets less than the recommended quantity (by weight) while Moose-dog gets more than the recommended. His metabolism is very fast, even at 8 years; while hers is much slower. Both are in very good shape, although some people look at her and think fat, but that's because she's got a square, squat and muscular body.