All day, your dog is busy eating, digesting, extracting nutrients from his food, and getting rid of waste. The gastrointestinal (GI) system processes these activities. It includes the mouth, esophagus, stomach, small and large intestines, colon, and anus. Many of the problems that crop up in a dog's life involve these areas. It helps to recognize important medical issues such as stomach trouble, vomiting and diarrhea, inflammatory bowel disease, and deadly bloat in the early stages so you can give your dog some relief.