Many dog owners that think that an invisible electric fence would be cruel to use on their dog probably does not understand exactly how they work. An electric invisible fence is not meant to ever hurt your dog, it is only meant to deliver a mild jolt that teaches your dog that they can not go outside the boundaries that have been set for them. This is for their own safety and your peace of mind.
When you are trying to choose which type of invisible dog fence would best suit your yard space and your dog, there are a few things you need to know before you make a purchase. If you have a relatively flat yard, then you might be better to go with a wireless invisible fence system. If your yard has slopes or metal buildings, then your best choice would be an in ground wired system.
Another aspect to consider if how well behaved your dog is or is not. If they are already well trained to obey commands and are easily teachable, you may need a fence system that only uses a few of levels of correction. If you have a dog that is very hyperactive and has problems obeying commands, then you may need a fence systems that has several levels of correction. This way your dog can learn one correction at a time where they are allowed to go and not go.