Hydration is crucial when a dog's stomach is upset, states Canine Journal. A dog may naturally be driven to eat grass and expel the offending item, but if this does not occur, a diet of rice, boiled chicken and banana baby food can settle the dog's stomach.
Other foods and treatments that can help settle an upset stomach include plain, unsweetened yogurt, pumpkin, oatmeal, sweet potatoes and bananas, according to Animal Sense. A dog can also be given small quantities of Pepto-Bismol. While the dog is vomiting or has diarrhea, however, food may only agitate the stomach and prolong symptoms, so Animal Sense recommends fasting the dog for 12 to 24 hours. Once the fast is over, a bland diet of rice and boiled chicken prepared without any oil or seasonings can help reawaken the dog's appetite without upsetting the stomach. Mixing the regular dog food in with the rice and chicken in slowly increasing quantities helps keep the dog's stomach stable.
Dehydration is the key danger when a dog is vomiting or has diarrhea, warns Canine Journal. Warning signs of dehydration include dry gums and non-elastic skin. In this scenario, water may not be sufficient to keep the dog hydrated; supplementing the water with powdered Pedialyte can help replenish electrolytes and vitamins. If symptoms last more than 24 hours, medical attention is required.