This is a short interesting article with graphic pictures of the effect of dog attacks on domestic livestock. He stretches some good points by confusing general statements on individual dogs free roaming dogs with the effect of dog packs, both domestic and feral.
This does emphasis the need for dogs to be under control when off leash, but also the more extreme instances in the report cannot be applied to dogs under control.
http://agrilife.org/texnatwildlife/predators-and-predation/predator-species/dogs/