What's the deal on pork and dog food?

WyoTraveler wrote:
May not be the food that is causing the gas in your dog. It may be that be that the dog is not getting the exercise needed for the food to properly digest. Never had a dog that got enough vigorous exercise have gas. I did have an old dog in his last years have gas because he ate and slept and never moved around much. Ever see an old man walking down the street and hear that gas at every step? I would feed your dog good good quality dog food and take him for exercise every day.:S

You may of hit on an answer. They don't get out much for exercise in the summer 110* heat here in AZ. One of the dogs had heat stroke while in the yard with me.It doesn't take long. Since then I don't let them out for more than about 15 minutes. I've run the food gauntlet, all grain free and most limited ingredients /limited calories. Blue Buffalo, Taste of the Wild, Calf. Natural, Balanced Diet, Zignature, etc. in flavors of beef, fish, duck, turkey, venison, etc. I'm now trying store bought raw that they ate two 3# bags and don't like it. I divide about a cup of ground chicken, fat rendered off, between the three dogs. Doc said maybe a chicken allergy. About a half dozen turkeys later, still some gas days. He had the Pit Sonogramed for internal problems, all ok. They were a bit overweight but are about right now. The Rottie needs to lose another 5#. The Shepard eats the same diet and has no gas problems. The Vet said he thinks I about covered the food allergy question. I should hope so. It's hard to figure out being they don't have problems at the same time and only about every two weeks. They won't eat anything for about a day until it passes, then back to normal. They don't gulp their food and drink enough water. The weather has cooled down some so I took them out yesterday and intend to keep at it. The Rottie has Valley Fever and gets short of breath so we have to take it slow. It's still better than no exercise at all..
Anyway, I'm going to step up the exercise and I thank all you folks for your suggestions.