My male "Hoagy" can "clear the room" in seconds every evening.  I don't know why he is so very...uh... "fragrant"!  He is properly wormed, the vet has tried a couple of things (one of them antibiotics for 3 weeks), but it hasn't helped.  I really don't know how I could change the food significantly, as I am already pretty careful what I feed my 7 dogs.  Their food is gluten- and lactose-free, for whatever that is worth, with a high percentage of protein.  I don't really want to get into never-ending and emotionally-charged discussions about "nutrition", as each person is convinced that their way is best, and that's OK with me.  But does anyone have any suggestions about flatulence?  The poop, BTW, is perfectly OK.
Thanks.

have you tried adding a probiotic?

Have a check if the food contains any sugar-beet pulp, its used as a bulker. Over the years we had 3 xbreeds, 3 GSDs and a Rott. Only one ever affected was the Rott after the makers changed the makeup of the food, she could clear the room in seconds, you NEVER followed her going up stairs and we sat in the car at a dogshow in a thunderstorm with front windows wide open and umbrellas up through the windows to keep the rain out so we didn't suffocate

We read the ingredients list very carefully, went back to a very similar previous food and solved it.

Is the protein in his diet from one source or multiple  types of animals? I would try changing his diet as it could be he can't have a certain type of animal, if it's a single protien source try swapping to a diffrent type or if it's a multiple source one start off with swapping to a single protien source at first then start adding in others over a period of time.

Mine can't have fish, any fish in the food and OMG the farting never stops! We had a month of it once when the ingredients changed in the food I was then feeding to include alot of fish.
Beef will also cause a bit of farting when we give her some but nothing like the fish.

My boy the last week has awful flatulence.  The smell even outside is awful. His wormed and anal glands ok... He was loose 10 days ago I did rice/veg and then pasta/bit of chappie. Back to normal but the smell!
So if I buy a priobotic for him which is best?  The drinks like yakult or yogurt?
Weird just had this image of said dog drinking yakult out the bottle in sunshine! I swear it was one small glass of wine at lunch time.

Flatulence (gassy dog) is something I'm really hot about, living with a breed prone to GDV (and despite my best efforts, having had 4 cases, 2 'fatal' over the years).    I avoid cereal-based food as much as I can, and especially feed containing soya.   I test - drop a piece of kibble in warm water to see how much it expands too.    I have seen no relationship between protein and gas much as other than with puppies (and even then I keep a puppy food at no higher than 26% max), I tend to look for a food that's no higher than 22% protein.    Apart from the last case, years ago now (fingers x-d) where he was 8, fit and healthy and still on good exercise, the other 3 were elderly males.  

Most dog food contains probiotics these days, but you could try adding a bit of natural yogurt and see if this helps.

If you are looking for probiotics try Kefir. It is a polish yoghurt drink found in all the major supermarkets. It has a higher concentrate of live good bacteria and is better for canines than plain yoghurt. Some if not most is made from goats milk. Could try googling it.

Flatulence (gassy dog) is something I'm really hot about, living with a breed prone to GDV

I would love to know what GDV means.  All the abbreviations on this forum are becoming for me a real blockade. 
I do feed grain free, though not with such a low protein % as you do.  If only I knew what GDV was, I would know whether this might be affecting Hoagy as well.

Gastric Dilation and Volulus.  Commonly know as bloat.
abbreviations can be a bit of a pain!

OH!  Bloat!  For heaven's sake...  Thanks! 

GDV is Gastric Dilation - Volvulus which is Bloat, with torsion.   You can have Bloat, without it going to torsion which is obviously much less serious, although serious enough as with deep chested breeds especially, it can so easily go to a full torsion.

http://www.peteducation.com/article.cfm?c=2+2090&aid=402

Oh yes, here this is known as a Magendrehung, very serious (life-threatening) indeed.  I used to worry about this when I had my standard poodle (who died of cancer at age 9).  I'll never stop missing her.  I don't believe my small breed is very susceptible to this, but it is well to know that I should watch it carefully.  Thanks.

I suspect that dogs like humans vary in their reaction to foods, one of mine is a pretty good farter and the others fed exactly the same way don't do it at all, as long as the dog is well then why worry, granted it would be nice if they didn't but at least the humans have a dog to blame theirs on