As far as they can tell, the idea grew up many decades ago after a stuffed hero of the passes, Barry, was left in the basement of a Swiss museum. Museum workers used to eat their lunches in the basement, and, it seems, one of them left his portable wine barrel hanging round Barry's neck. The barrel was found when the museum rehabilitated the famous dog, and, judging it picturesque, the curators left it there. The rest is history.
The dogs themselves are still very much in evidence as they breed and pass the summer in kennels at the top of the pass. They are no longer used for avalanche search and rescue, however, having ceded their place to lighter, helicopter-friendly pedigrees.
Heavy wire also keeps any traveller from trying to approach the great animals: local Swiss still remember the day when one of the St Bernards chose to gobble up one too-curious child for lunch, even though it may have had no brandy to chase it down with.