You may be able to find a specific brand of food that diminishes the amount of gas your dog produces. The gas is generally due to a failure to breakdown complex carbohydrates before they reach the large intestine. If this happens, the carbohydrate is fermented and gas ensues. So when looking at different foods, make sure the carbohydrate source is different. If you have already tried multiple foods, try the product Beano. It is made for humans but can be safely used in pets. Typically I start with one tablet per 50 pounds body weight; however, you can increase the dose as needed as the product is extremely safe. It contains an enzyme which breaks down complex carbohydrates prior to them reaching the large intestine. The Beano needs to be given before the puppy eats. Also, encourage exercise just before retiring to the den for the evening. This, at least, causes the gas to be expelled outside!