Why does dog gas smell so bad?

I guess I have never had a dog that passed nasty gas. I feed them right so there shouldn't be any farting.

Try the dogs diet in that case and see how yours smells

Obviously, you're keeping your face too far away, when you huff. The gasses should go directly into your lungs, not be smelled first. See? Then you get high.  And be sure and pet Fido and thank him. *burp* (Okay, I'm just talking shlt.  ..he he. Get it?   :D 

My dog's gas doesnt smell that bad except when I give him a soft boiled egg.  Just like humans..the smell is probably determined based on its diet. 

The methane is from SUGAR in the diet.  Dogs are carnivores, yet most are fed a grain-based kibble which they have:

1) trouble digesting - it takes 12 hours to digest

2) grain digests INTO sugars which feed bad bacteria & thus you get nasty intestinal gas

YOUR SOLUTIONS:

 Either feed the dog either a sweet potato based dog food (low glycemic factor) or go to an approved RAW diet, (btw, the dog can digest in 4 hours) & should have zero sugars.

Rubbish in, rubbish out - in whatever form.

Most of the smell comes from bacteria, they have a stronger stomach and different bacteria and stomach acids than we do, which gives them their own distinctive smell.

I would guess it's tinned dog food.