I have my dog on a electronic shock collar, yet he still manages to disregard the shock at the highest level and he still gets through the fence.  So if a dog is very agitated it will make it through the fence.  Sorry for the loss of your dog but people have to understand that an electronic fence is not effective if the dog is running full speed.  If you have your pet on a shock collar please put up the little signs that come with it to serve as a visual reminder for the dog and for people passing by.