Get rid of the sulpher in the dog's food, and like cows you'll get CH4 instead of H2S. Attach baloon to anus and collect. I burns good, but isn't healthy to breath. Put sulpher back in in the form of methyl mercaptain (like the gas company used to do), and you can smell it again. In fact, almost all compounds of sulpher that don't have metals in them (except hydrogen) stink like h--l.