I don't understand..... were the sheep supposed to be guarding the puppies??
They don't say what the breed of dog was that the farmer raised.
If sheep were involved, they might have been a livestock guard dog breed like the Great Pyrenees for example. This type of dog is used for protection against coyotes, etc, for the sheep. In those cases the pups are raised with the flock. This way the sheep become part of the dogs pack as the dog grows up. It's best to get a dog like that use to being with the sheep from an early age.
Of course I'm just guessing at what the scenario might have been.