Being a positive methods clicker trainer does not make me a big fan of electronic fencing as it is grounded in punishment based methodology. Dog nears electronic fence field and dog receives a warning beep and then if he doesn't immediately retreat, gets shocked. Call it electronic stimulation, saying it is like a static electricity shock, IMHO, just is not true. It is a shock, and needs to be strong enough to discourage the dog from going through the invisible line. Try it on your own neck if you would like to find out how strong it really is (kidding here, I would not do that, too close to my brain). You could however, put in on your arm to get a real idea of what your dog feels.
That being said, where I live, it is a reality that a high percentage of my clients install invisible fencing. For me, nothing beats proper height and well installed physical fencing. It is what I have with my own dogs. Keeps them safely enclosed, and keeps other animals out.
As a trainer I have had to learn to adapt and live with it, so here is my take on using electronic fencing properly:
1. It is not meant to be a dog-sitter. Dogs should be let out to go potty, or for extended periods for play, with owners present. You should always have your dog under your verbal control, and your dog should be off-leash trained BEFORE you install the electronic fencing. Otherwise, the only thing you will have is a dog that won't leave your property, but how do you get him back inside if he prefers to be outside.
2. Never leave your dog outside and go run errands or horrors!, go to work for the day. Your dog could get so distracted that he runs through it, receives the shock, and now won't come back in knowing he will be zapped again. Result, you could lose you dog, and you weren't even home to know where he went and were unable to do anything about it.
3. Prolonged alone time outside can cause your dog to be a neighborhood nuisance. Some dogs bark all day and run the fence line barking and carrying on whenever someone passes by.
4. Over time this can cause an aggression problem. As your dog barks at people passing by, he believes his barking and guarding your property kept them away. The fact that they were never really coming to visit is something he doesn't know, and their continuing on their way is reinforcement for the dogs aggression. I can't tell you how many of my clients dogs have eventually bitten someone entering the property, despite my warnings not to use the electronic fencing with the dog unsupervised. You need to be especially vigilant if you own a breed bred to be a watchdog, your UPS man will not understand your excuses.
5. Fencing should not even be considered until your dog is completely house trained.
Getting shocked can freak out dogs so much that they revert to pottying in the house as they feel the outside is no longer a safe place to eliminate.
IMHO they should be at least six months old. Baby dogs should not have to encounter this type of severe correction, it can traumatize them and cause them to be afraid of their own yards. Even with older dogs you need to often do a lot of play therapy outside to convince them are safe. I have seen dogs refuse to leave the front step or deck for months.
6. Don't include your driveway. Since electronic fencing has become so popular, I have known five dogs that have been either run over and injured or killed by a car in their own driveways. In one case the owner did it not realizing his dog was sleeping under his car to get out of the sun. And this dog was a puppy, what a tragedy for all.
Also, dogs will often jump on peoples cars in their eagerness to say hello to your guests. A great way to become more popular with your friends and family when your dog scratches their new vehicle. Again, dogs need to be supervised at all times.
7. Keep your flags up! I think this is only fair that your dog also have a visible reminder as to where the boundaries are. Since flag shaking, and running away and saying WATCH OUT are part of the training, why take the visible reminder that you used to train the dog away. When dogs get zapped by the fencing they often have superstitious learning anyway. They will think it was the rock they were standing by, or that pine tree, not really understanding that they need to stay away from the flags. So keep up your flag shaking until they understand fully, and don't then take them away when they finally understand. So unfair.
8. Don't ever cross the boundaries when your dog is outside with you. Your dog should never be punished for following and staying with you. That is what we all want, isn't it? So no crossing the line to get your mail, say hi to your neighbor, or having your children run in and out of the line. Dogs that follow their people are good dogs. If anyone is going to cross the boundaries, bring the dog inside first please.
9. Be real about your dogs limits. If you look out your window and see a herd of deer on your property, that may not be the best time to let your dog out on his electronic fencing. Some dogs have a really strong desire to chase fleeing animals, don't tempt fate and lose your dog. Maybe leash walk him instead, and when the deer have disappeared, then you can let him loose again.
10. Constantly maintain and check your system for proper operation. Check the batteries in the collar often. And please, don't think your dog is so trained he no longer needs to wear the collar. Use the equipment you paid for, keep your dog as safe as you can.
11. Supervise the person included in the electronic fencing package that is doing the training. They should never ask you to call your dog to get it to go through the fence. I had one client whose electronic fencing trainer did this because the dog would not cross the line to get zapped. That dog would not come to it's owner for months, and I had to be called in to fix the problem.
12. Be careful when you play fetch a ball, stick, or a frisbee. Don't throw toys across the line, not fair, and let's not tempt fate. You don't want to be the person who caused your dog to get shocked when he was just trying to play a game with you.
13. Once again, not a dog sitter, Supervise, Supervise, Supervise. Remember it is not physical fencing, your dog can run through it, you need to be there if that should ever happen. Or better yet, have your dog under your verbal control (which means a trained off-leash dog), and prevent problems before they occur.
Love, Train, and Supervise your dog. Better safe than sorry.