Passing gas is a sign of poor digestion. Have you recently changed her diet? If she drags her bottom against the floor or in your case a stuffed animal, it's possible that she's suffering diarrhea. Is her stool normal? No blood and no mucus(黏液)?
You should put your dog on a balanced diet with about 28% protein and 3% fiber, give the dog a lot of water, but regulate her food intake as suggested on the label of your dog chow. Some better brands of dog kibbles are:
Nutro
Wellness
Natura
Innova
Wysong
California Natural
Canidae
Holistic Select by Eagle Pack
Newman's Own
Chicken Soup
Naural Balance
Royal Canin higher end stuff