Sorry to hear of your canine conundrum Viking, but this reminds me of my dog 'Barney' who sadly is no longer with us.  However, many years back Barney used to let rip so violently and with a tremendous-sounding rasp that he scared himself and would then make a mad dash for a place of safety.  We always thought that the poor dog didn't even know that he was the culprit.  The problem with his emissions were that they were incredibly smelly and one of his little tricks was to creep behind the sofa when all the family were assembled and watching the box, and emit a silent fart (this type of flatulence he seemed to know were down to him).  This was greeted a few seconds later with a group exclamation of 'BARNEY!' and the poor dog would then be forcibly ejected from his normal hiding place to the garden.

The problem, we discovered, was vegetables, (usually leftovers from our dinners).  His constitution could not handle their digestion, although he always liked to whoof down all that he was given.