Long term treatments for dog digestive problems might be related to changing your pet's diet, or the way he eats.
Things to consider: How much and how fast the dog eats, dealing with gas, and how to change food.
Slow Down, Cut Back - Digestive troubles like frequent diarrhea or vomiting could be caused by overeating or eating too quickly. While dog medicines may relieve the temporary symptoms, if diet is the problem, further action is required. Cutting down portions is an obvious start, but unless your dog has a weight problem, you do not want to take the risk of under nourishing him. What you could do is combine those smaller portions with more frequent servings (say 3 small meals a day instead of 2 large ones).
Digestive Medicine for Dogs - Stinky dog gas is a problem that many dog owners suffer from. Fortunately, what helps prevent gas in humans -- HCl (that is hydrochloric acid) tablets for digesting proteins and digestive enzymes for digesting carbs -- will also help prevent it in dogs. HOWEVER, the dosages for humans and dog medicines to aid in digestion are decidedly different. That is why, as a supplement with your dog's daily meals, add a digestive enzyme capsule or HCl tablet made specifically for dogs.
Slow Transition - When changing your dog's food, change over gradually, mixing mostly the old food with a little of the new and, with each serving, slowly increasing the proportion of new to old. This will help you save your dog from serious digestive upset because of any nutritional shock to her system. An acceptable exception to this, however, is if your dog is already suffering from digestive troubles. Then you are free to make an immediate switch to bland dog food for a period of time. When his digestive difficulties disappear and you return him to his old food, do it gradually, as instructed above. That will keep you from unintentionally causing any new digestive troubles.