Give Science Diet a call: 1-800-445-5777 from 8 a.m. - 5 p.m. CST, Monday-Friday (per their website)
There are many causes to stomach issues in dogs, and not knowing what is wrong with your dog, you'll have to trust your vet. On the other hand, a lot of stomach issues in dogs are resolved with more natural food, with fewer processed ingredients. (Much like people... no surprise.) We stick to smaller companies that use whole ingredients and don't have PN/TN on site: Acana/Orijen and Innova/California Natural. Not sure if your vet would recommend either of those for your dog's condition.