JMO I would never use one..
Hidden fences do not keep people and dogs out of your yard, leaving small dogs vulnerable to attacks by larger ones and exposing all dogs to potential teasing. If two dogs are confined within a system and one breaks out to chase a cat or squirrel or another dog, the remaining dog usually follows. If the dog gets too agitated or the distraction is too strong, many dogs forget the pain and run through the system. Once out, when the distraction is over, the dog may not come home because he knows he will get shocked. The receiver collars don't work well on heavy-coated dogs, so some hair shaving may be necessary.
Disadvantages
The advantages of an underground fence are clear, but the disadvantages are at least as clear for some dogs and owners and for meter readers, mailmen, joggers, and dog walkers.
Underground fence cannot be seen by the people who come to or walk past the house, so visitors, servicemen, and walkers may be startled or frightened by a charging dog protecting his property. Underground fence is also invisible to the critters that inhabit suburbia — rabbits, stray dogs, and cats may enter a yard with disastrous results.
Some dogs have a high pain threshold and will go through the barrier if the distraction is strong enough. Once they go through, they receive the correction when trying to re-enter the yard and may be reluctant to return when the chase is done.
Success of the system depends on maintenance by the homeowner. Batteries must be replaced, collars must be fitted correctly, and contact between the prongs and the skin must be maintained. If the dog has a thick or heavy coat, it may be necessary to shave his neck for contact to occur.
Kerry McManus of Cincinnati Invisible Fence, (Cincinnati, Ohio, USA) said that he does not sell the system to contain dogs that have a history of aggression, biting, or running away. His company will install fence around the perimeter of the property and put in side sections to keep the dog in the back yard. The front yard is fenced to minimize the chances of the dog escaping if it slips out the door, he said.
However, many people allow the dog unsupervised in the front yard without considering the impact of a charging, barking dog on the neighborhood. Although dogs will bark and jump at a traditional fence, a barrier that can be seen allows a measure of confidence that the dog will remain confined. Most joggers, walkers, and delivery men accept that a dog behind a fence is doing its job at a safe distance; with a hidden fence, there can be no such trust.
Because dogs can easily leave a yard with a hidden fence if the maintenance is not done or if the dog has a high pain threshold combined with high prey or defense drives, some breeders and shelters will not sell or adopt dogs to be confined by these fences. The large guardian breeds are particularly likely to have the characteristics that make underground fences a poor choice of confinement.
Dogs should always be safely contained so that they cannot be teased or injured by other animals or by children and so they cannot escape. If hidden fence is the only alternative to tying out, owners should research each company and each do-it-yourself kit to make sure it fits their needs. Then they should keep the collar in working order and supervise the dog while it is outside. If Tugger braves the correction to take off after a squirrel or Rambo ignores the shock to chase Mrs. Smith's Fifi, at least the owner will know his pet has left the yard. And if a stray dog gets in the yard and does a number on Sugar, at least the owner can rescue his pet if he sees the action.
