My Lab has gotten out a few times, but mostly think it was just dumb luck on his part, just saw or smelled something he wanted, and went for it. The fence is an old wooden privacy, which he could push right through if he really wanted out. Been about a year since his last escape. My last dog was a huge, Rottweiler-Curr mix, he always stayed close. Could even leave the doors open for the cat, and he would take off. Walked him off the leash most of the time, and would usually wait outside of stores, if I need something, but he would go in, if I took too long or it was really hot outside. Great thing about a small town, most of the locals don't freak out, but the tourists are terrified seeing a 140 lb dog roaming free.
Electric fence would be bad, and only temporary. Bummer if the dog took a leak on the wire, or a rainy day.