After reading several threads concerning fences, and dogs I thought I might make a few observations.
I was a land surveyor for about seven years and have alot of experience with trespassing. First off in MO surveyors are exempt from trespass but are liable for damages. They are NOT required to ask permission or inform.
#1 On dogs. You're big mean rot/pitbull/doberman is a sucker for a porkchop bone or a $.99 McD's cheeseburger. I've been in many back yards with "vicious" dogs and all it took was a little baby talk and maybe a treat. Yes if your dog is a barker he may alert you, but if your dog stays outside and your burgler is a pro the dog will be just as happy to see him as you.
#2 There isn't a fence made (short of razor wire) that a person can't get over or arround. Electrified you say? I used to carry some old speaker wire to ground out electric fences. No sweat.
#3 If you want your gate locked use a combo padlock and a hasp on the inside of your gate. There are only so many key patterns out there. We also had a big ring full of padlock keys. 5 minutes and we were in. If someone really wants in a 24oz ripper will either knock the lock open or pry the screws right out of the wood.
#4 Getting fancy with booby traps will get someone hurt and you in trouble. Land surveyors, utility workers, meter readers etc, may need to gain access to your yard while you are at work or out of town. Some cutesy booby trap that will "only hurt you if you're doing something you're not supposed to be doing" may hurt someone that is just doing their job. BTW if you have a utility easement in your yard (check your deed) you have to allow access to your yard. If you don't they will think nothing of cutting down you 8 foot privacy fence to get the backhoe in.
#5 Pay attention! I don't know how many times we parked a big white truck in front of a clients house, marched arround their yard for two hours, finished the job, knocked on the door to let them know we were done, only to be met by a homeowner saying "oh you're here?" Umm we got here 2 hours ago where were you? I'm not saying sit by the window with binoculars all day, but a peek out the window every now and then is a good idea. SA doesn't end when you walk in the front door.
#6 Thorny vegitation. Well, one of my old crew cheifs most common sayings was "I's born and raised in uh brar patch". Machete's are cheap and there is no waiting period or background check.
I realize alot of these comments are toung-in-cheek, but I just thought some of these observations might be usefull.
BTW if you plan on building a fence, call a surveyor. It's alot cheaper than a law suite and you may find out your yard is bigger than you thought.