It used to be that truffles were hunted in the wild by sows - the pig has a great sense of smell. But they wouldn't hand the mushrooms over so dogs were trained. They're good at it and can be trusted (usually) to bring the truffle back to their master.
I spent a morning at the Domaine Bramarel in SE France watching these dogs at work. They're trained almost from birth to love truffles and find them. It's easier these days because truffles tend to be farmed so there's no gallivanting through the woods.
The idea of hunting truffles (worth $1200 a kilogram, by the way) isn't a chore for the dogs, it's fun. They see it as a game, one with a lovely reward at the end. If they find a truffle, they're given a biscuit - or even a truffle, but a piece of the cheaper varieties.
The Domaine Bramarel organizes visits, on weekends in winter and on weekdays in summer. Just email (the owner's wife is perfectly at ease in English) and ask if you can join a group for a visit. If you love truffles, you can also buy them there at prices lower than you'd pay once they're on the open market. Even so be ready for a shock when the bill comes.
Love truffles but can't afford the Black Diamond? Buy some truffle oil. It's delicious and perfumed and if you close your eyes you'll feel you're eating the real thing. And you'll still feel your wallet has something in it.