The pastou is not so much a sheep dog as a dogsheep.
White, woolly, and normally docile, the Great Pyrenean mountain dog, to give the animal its formal title, hardly looks the sort of beast to see off a marauding wolf.
But appearances can be deceptive.
"When they are with a flock, they are quite peaceful dogs, but when they get angry, it's for real," says Christel Durand, who has spent the last two years training pastous in the French Alps.
Pastous are descended from Tibetan dogs, as are all the 25 breeds used to protect livestock around the world. Until recently they were to be found only in the Pyrenees Mountains along the French border with Spain, where they had long guarded sheep and cattle against wolves and bears.
So when wolves first appeared in the Alps, sheep breeders and naturalists trying to help shepherds deal with the new threat quickly turned to pastous as dogs with experience.
While shepherds in the Alps have always relied on their sheep dogs to help herd their flocks, pastous play a completely different role. Indeed, while a solitary shepherd often develops an intense friendship with his sheep dog, he must deliberately avoid getting close to the pastous in his flock.
Ideally, says Ms. Durand, a pastou pup should be born among the flock he is to guard. "The flock must be his family," she explains. "He must eat with the sheep, sleep with the sheep, live his whole life with the sheep. They are his masters, not man."
In this way, the sheep grow comfortable with a dog in their midst, and the dog stays close to the flock at all times, instead of following the shepherd.
This does not happen all the time. All it takes is for a sheep breeder to allow his children to play with the adorable pastou pup in the sheep barn, and the dog is useless on the mountainside. On the other hand, dogs that have not taken properly to their flock can frighten ewes at lambing time and cause all sorts of trouble.
Even dogs that are well installed in their sheep family cannot provide 100 percent protection: Shepherds tell stories of watching one wolf launch a diversionary attack to draw the pastou's attention, while other members of the pack attack the flock from the rear.
But for the time being, they seem the best that shepherds can find. "I used to sleep with my cabin door open," says Didier Castelle, a shepherd who now uses pastous.
"This year I could shut my door and sleep peacefully. I knew the dog would wake me if a wolf came close."
(c) Copyright 1999. The Christian Science Publishing Society