Jessica,
One German Shepherd show kennel that I know of feeds SportMix Chicken & Rice, a pretty simple formula, without legumes (or potatoes) or gluten. And the dogs have been doing well on it.
It has that very moderate (to moderate high) protein & fat that most GSD show breeders tend to favor, 26/16.
https://www.sportmix.com/dog-food/wholesomes/wholesomes-chicken-meal-rice-formula/
I don’t know much about the line, other than that it is owned by Midwestern Pet Foods (which itself is owned by an old milling company, Nunn) which makes Earthborn, a brand that seems to have much more visibility and promotion.
Earthborn Holistic, with its many grain-free formulas, was heavily implicated among the DCM case reports to the FDA, while Sportmix was not.
