Thats an awful thing to happen. The dog must have jumped into the pigs enclosure? I have a large male GSD, and he is never, ever, allowed anywhere unattended, or even off the lead where there are other people, or any animals, even our own who is he used to. To be honest, that would apply to any of our dogs.
Hopefully the poor little pigs will recover from their dreadful ordeal. I would think this has been a wake up call for the dog owner, but really the pig owner needs to stress, that she must keep the dog under control and well away from any livestock, as its obvious it will attack. I hope the dog owner has the decency to offer to pay for any vet treatment, etc.