Are electric fences harmful to animals?

Absolutely. Electronic Dog Collars or Dog Shock Collars are safe. Many many years of testing have gone into making them both effective and safe to use. There are several different types of Dog Training Collars, depending on what you need them for. There are three main types of Shock Collars for Dogs.

1)Dog Training Collars: These have 2 primary uses, Hunting and Obedience Training. Electronic Training Collars for hunting are normally used to train the dogs when they should return or stay or seek, and sometimes to locate the dog using a Beeper or a Light.

2)No Bark Collars: These types of Electronic Collars are designed specifically to keep dogs from Chronically Barking. Some of these Bark Collars are triggered by the sound of the dog barking while others combine the sound of the bark with a Vibration Sensor, so as to eliminate unwanted Corrections from nearby dogs or other noises besides barking.

3)Electronic Dog Fences: There are two types of Electronic Dog Fences, Wireless and In-Ground. Wireless Dog fences have the advantage of being very easy to install and use but they have a limited area that can be enclosed. They are also portable so they can be brought to the beach or on vacation with you very easily. In-Ground Fences are in general more powerful and there is a much greater selection of models available. They are also capable of covering a much greater area, some up to 40 acres, in multiple configurations. For example you are able to enclose your yard so the dog cannot escape while also keeping them away from the pool or from digging in your rose or vegetable garden. The layout for In Ground Electronic Fences is near infinite depending on your needs.

Another View:

They are safe in that they won't fry your dog if they are working properly, but they should only be used by those trained in their proper usage. They are a powerful tool.