My dog had a mesenteric torsion surgery & had 30% of his small intestine removed. He recovered and is doing well except for horrible gas. Do you have any recommendations?

My 1 1/2 year old Golden suffered from bad GI issues as a pup. Ended up having surgery at nine months: vet called from OR and said it's mesenteric torsion. Basically asking if I wanted to stop the surgery and put the pup down. I decided to finish the surgery and see what happened. Vet removed an estimated 30% of the small intestine. Miraculously the dog recovered and is thriving with no apparent side affects, except the dog has terrible intermittent gas. I had him on Pro Plan salmon and oatmeal for sensitive stomach and skin (vet's recommendation). I recently changed him to Horizon. Gas is better but not 100% better. Any recommendations for food or anything else to improve the situation? Stools are normal.
But the gas can kill us!