If we tried to invent the cruelest punishment for dogs, we probably couldn't come up with anything worse than "solitary confinement" on a chain or in a kennel. Dogs are pack animals that crave companionship. Most people who chain dogs just don't realize that scratches behind the ears, games of Fetch and walks around the block mean to world to dogs. Time spent inside with their families and curling up at our feet while we watch TV is their idea of heaven. Many dogs left to fend for themselves at the end of a chain fall prey to attacks by other animals or cruel people, and many others are injured or hanged or choke as a result of getting entangled or caught in their tether.
Dogs are very social animals and when you adopt a dog you are welcoming that dog into your family. Dogs need stuff to do. They become bored very easily and, therefore, chaining a dog for long periods of time threatens their mental health. Many guardians make the mistake of chaining their dogs because they misbehave, but don't realize that isolating dogs for long periods of time causes this behavior. Before making the decision to adopt a dog, make sure you have the time, energy and space for one.
Although you may be giving your dog food, water and vet care, that is not enough. Chained dogs may become withdrawn and depressed and usually try to find ways to keep themselves busy by compulsively digging, barking and chewing. Many dogs become aggressive with neglect and then are taken to humane societies, or worse, euthanized due to behavioral issues that were initially caused by their guardian!
Many people don't realize the stress put on dogs who are continuously chained or isolated in small kennels for extended lengths of time. Dogs that don't receive enough exercise and attention can be hyperactive, anxious, aggressive, neurotic, territorial and even dangerous. Dogs have also been known to grind their teeth down to stumps or compulsively lick an area of the body until it bleeds. There are plenty of responsible guardians who understand that their dogs are happier to be outside some of the time, but no dog is happy to be alone. And many well-trained dogs are safely tethered with overhead cables in the yard for short periods of time when the guardian is inside the house.
Please think of these issues before you adopt a dog, especially a medium to large athletic, active dog. Do you have a yard for your dog to play in where you know they will be safe? Do you have time to take the dog for walks? Do you have the time to train your dog so they can be raised as part of the family in the house? Pets, and especially dogs, need and want contact from you. Your dog only has you. Your dog is depending on you to make his life a good one or a terrible one. His fate is in your hands.