Try Natural Balance - and Beano - check with the vet

Not sure if it is available where you are but my cat had undesirable bowel incidents as a kitten and young cat. The vet recommended 'James Wellbeloved'. I get it from specialist petshops. Not only does my cat like this food but it also seems to keep his innards functioning favourably, unlike the too-rich mush you get from the supermarket. Google it and mail them asking for suppliers near you.

I don't know a thing about cats, but I give my dogs a little plain yogurt every morning and the air stays much fresher in my house now.

Dogs can gulp air when they eat, just like humans, and that causes excessive flatus. My DD has a Rhodesian Ridgeback who develops gas when he gets nervous, too. If the flatus is really foul smelling, it suggests to me that his intestinal flora are out of whack. This can happen for any number of reasons, including a course on an antibiotic. I really don't see where yogurt would hurt, and may really help, by introducing good flora back into his gut. It's cheap and worth a try. Ask your vet.

Did your vet check for giardia? It's known for foul-smelling wind (and extremely toxic runny poo).

I'll add my vote for a little yoghurt from time to time. But please make sure that it is not one of the varieties that is thickened artificially with corn gluten, corn starch, or other plant based starches. Those using gelatine as a thickener are acceptable. I always have plain Greek yoghurt on hand. It is made of milk and culture with no grain thickeners nor gelatine (the very thought of gelatine makes me cringe) and is very good. I eat a spoonful, one of the cats gets a spoonful, I eat another spoonful, another cat gets a spoonful, and so forth until all cats have had their spoonful. You can also purchase probiotics at the market, most are acidophilus although others exist. A quarter to half probiotic tablet once or twice weekly should do the trick. IF this works but you find that you need to feed the probiotics forever and ever, you might wish to find out why the cat's flora are always off.

You may also need to consider getting your cat off of grain-based foods. Cats did not evolve to eat grains, which feeding can lead to serious chronic health issues later. Spend a little more to get your cat onto grain-free foods.

I did this with my youngest male Fionn, whose emanations would make the angels faint, they were so bad and far-reaching. He still had the gusty wind, even with the grain-free dry food. So I stopped feeding him dry food altogether. He's no longer windy. None of my other cats are flatulent after eating dry foods so this was a surprise. I no longer feed dry, but do keep Natural Balance Limited Ingredient Duck & Pea on hand. It makes a much healthier treat than do commercial cat treats (which are made up of corn, wheat and soy with a little animal fat added for flavour). The Natural Balance tinned foods are good-I feed only the Limited Ingredient tinned. Your Science Diet is a grain based food.

Reading labels helps. They're too tiny to easily read while at market, so check the below referenced link-it's a commercial pet food and supply company, but they have label information on all the foods they carry and it's much easier to read them on the pc monitor.

Oh, and cats can gulp air while eating too. Slowing their eating helps. Some say to put a tennis ball on the food so your cat must work out each piece from under the ball. When I tried that the cat just pipped the ball out with its paw and hoovered up his food, business as usual. Feeding wet food slows the eating too. You can also mix water with your cat's food so he must lap it up instead of inhaling it in.

Sorry this is so verbose. I'm throwing a lot of ideas out in case one might be helpful.

Here is a link that might be useful: Pet Food Direct Cat Foods

How old is your cat.... and also is he neutered?

Those are my first 2 questions... not sure they would lead to any diagnoses (since I'm not a vet) but I have to ask.

thanks for al the replies.

Beano - can you give that to animals???

I'll check out the ingredient list on foods when I get into Petsmart and I'm not sure where there is a specialty store but will check it out.

I'm giving him yogurt and did right after it started - no change.

Lucky is 11 and he was neutered when he was a kitten.

I will ask the vet about giardia.

thanks again for the suggestions