Well this isn't one of my favorite topics I just had to ask... My dogs have terrible gas including Lincoln my Goldendoodle. I feed them Blue Buffalo Large Breed, and Blue Buffalo canned Chicken and Brown Rice, Lamb, and Fish with Sweet Potato. I'm also letting them eat Pork raw hides, and give them Mother Hubbards biscuits. I never feed them table scraps or people food except maybe a real piece of chicken or beef or potato every now and then, but not often. Help I'm being fumigated on a daily basis!!!!
Feeding cats is much more complicated and tricky than feeding dogs. Cats are classified as "obligate carnivores", which means they cannot survive without animal protein and a certain amount of fat in a very specific proportion. Cats are much less tolerant of poor diets than dogs, and seem to become malnourished and ill much more easily.
I cannot offer any advice on feeding cats, except that veterinary RX foods are garbage, and to add insult to injury, premium priced garbage. Maybe you can find advice about this in cat forums.
You can buy Blue Buffalo at PetSmart. Not sure about Petco. We can buy other specialty foods at Pet Supplies Plus. You can also buy some of these foods online.