When I first started my puppy on Orijen puppy he was really gassy. I had to switch him very slowly and mix it half and half with his Innova puppy for quite awhile. He also had a bit of runny stools for awhile with it. Now that he has been eating it for about 6 months he does great on it and I won't switch him off of it. But he doesn't do well on all of the grain free. He didnt' do well on Natures Variety that I had left over from my Lhasa. Both dogs had terrible diarrhea and gas on it and I think one of the ingredients in it just didnt' agree with them. It has a TON of ingredients that they hadn't been exposed to before and I'm not sure which one it was that upset them but I never tried it again. You may want to try a different grain free if the gas doesnt' stop after a slower introduction.