How long has it been going on? I just went through this issue with my dog. He had the worst gas I have ever smelt. At first I thought he got into something, but after 3 days of the odor, I called the vet and took him in (he was due for shots anyway). Turned out, he had a "flu" like virus. the only sign we noticed was the gas, no diareha, vomiting, still energetic, ect. She gave him some antibiotics, and put him on a bland diet of : 2 hard boiled eggs, 1 cup plain yogurt, 1/2 cupt cottage cheese, and 1 Cup white rice. Feed him/her this 3 to 4 times a day 9but do not exceed the normal feeding per day. if he ususally has 4 cups of dry food per day, keep him at 4 cups of the bland diet) do so for a week...if that doesn't help, Id call the vet