Even after the SUSF representative came out and "retrained" her by putting a second shock collar around her groin to keep her in the yard, this previously aggression-free dog continued to run through the fence and attack dogs and humans passing by.
* A SUSF doesn't protect your dog from intruders (other dogs, humans) and hence puts her at risk from them (maybe an aggressive stray dog, a rabid fox who wanders into your yard, or a human with evil Intentions), and puts innocent intruders at risk (a child, perhaps) especially if your dog has become aggressive due to the shock association.