Hm...Jax08 and Gretchen this is kind of alarming. Does that mean every time Smokey doesn't want to eat I should throw out an entire bag of kibble? What if Zeeva eats it just fine but Smokey doesn't???
When this happened with my previous dog - the Vet labeled her a picky eater, but I knew better - she had Cancer. If I force my current dog to eat something she does not want, her colitis flares up. Always
trust your GSD.
Something like this happened when my cats were kittens - similar situation as described by Jax08.
You have two different breeds, they probably have different needs. For example Huskies were originally fed a fish based diet, GSD's were not.