
My friend has a GSD with a very sensitive tummy. she had her on a food for ages that suited her, and then they changed the formulation.
She now feeds Arden Grange Classic Lam and Rice. The dogs are really good on it.
It is a dry food, but your dog will learn to eat it if you mixz a spoonful of her tinned meat with it, until eventually you can stop.
Tinned food often gives horible smelly sloppy poos, and lots of them. It is an expensive way to give water, as they are 80% water.