An invisible fence is an animal control mechanism wherein a dog is given a collar that emits an electrical shock if he ventures too close to an underground wire. This underground wire can be run around an entire property, and since there are no visual markers for it, it is called an invisible fence. Setting up the collar is one of the most important parts of an invisible fence system, since it is the part of the system that will interact with your dog and teach him not to cross the fence line.
There are various types of invisible fence collars, but most types offer a computerized control that, when the collar approaches a fence, begins to beep loudly for several seconds, warning the dog that she is straying too close to the boundary. If this warning is not heeded, the dog will receive a short electrical shock. The beeping can be adjusted to occur closer or further away from the fence, depending on the type of conditioning you want your dogs to have. The further away you set it, the longer it will beep before delivering a shock to your animal.
In addition to audible warnings, the main feature of the invisible fence is the shock that is delivered if an animal strays too close to the fence line. This shock level is fully adjustable to the size and weight of your animal, as well as its disposition. For example, if you have a large, stubborn dog that seems to ignore low-level shocks, you can adjust the collar to deliver a more powerful shock, which will cause the animal to react accordingly. The shocks delivered by the collar are rarely painful, and cause more surprise than anything else.
Invisible fence systems also come with small flags which you can place at the boundaries of the fence line that is installed. These flags provide visual cues that let the dog know not to stray too close to the fence. Once the dog has learned where the fence line is, either from the flags, beeping, shocks or a combination of all three, the flags may be removed, and the dog can be allowed to roam the property with just the collar.