There are some medical reasons for some dogs to eat a diet with alkalinizing vegetable and fruit and plant based proteins . Soy is not the only option for this . Hemp flour is one source . The medical reason , for which you can have a DNA evaluation , just as you would for DM , is hyperuricosuria , common in Dalmations, but GSD are on the list "
Detailed Hyperuricosuria Information
The VGL offers a DNA test for hyperuricosuria to assist owners and breeders in identifying affected and carrier dogs. The test uses DNA collected from buccal swabs thus avoiding invasive blood collection. Breeders can use results from the test as a tool for selection of mating pairs to avoid producing affected dogs. The test is offered to all breeds, including Dalmatian, Bulldog, Black Russian Terrier, Weimaraner , Jack Russel/Parsons Terrier, Pitbull, American Staffordshire Terrier, Giant Schnauzer, South African Boerboel, German Shepherd, Large Munsterlander, and Australian Shepherd. "
This was brought to my attention at one of the "health" shows I attended - stand still enough and someone will bring a problem to you - expand your horizons on what is out there.
On this site there are many recommendations for sweet potato treats , sweet potato in kibble, or as a substitute for pumpkin- well sweet potato is high in oxalates which is kidney stone forming . I *think* pumpkin may be in the high category???? not sure .
For an antidiarrheal then carob which is low in oxalates is a better choice.