Many people think of a dog being loose in a garden as a cure-all. In reality, the garden can be a cause-all, leading to all sorts of behaviour problems. How many of you think you can't get a dog because you don't have a garden? Do you know that often, a dog will be given to someone without a garden, rather than someone with one?
People sometimes mistakenly believe that a dog, like livestock, will be happier with fresh air, grass and more room to "run around." But when did you last see a happy, relaxed backyard dog "running around" his yard? Such dogs are inevitably sad, bored and lonely, wanting only to be able to spend time with their families in the house. When they manage to get human contact, they are desperately over-excited from deprivation and are likely to misbehave. Because they behave like crazy animals, they are sent back to the yard. It's a vicious circle.
Because they spend so much time in the yard, they never develop house manners or social skills and are left outside.
Dogs were domesticated by humans to perform a variety of functions, the most common of which is now companionship. Dogs are pack animals who form extremely strong social bonds and whose most important psychological need is to be around the people they are bonded to. Making a dog live in the backyard is unnatural - they need to live with you.
Backyard dogs suffer from greatly increased incidence of behaviour problems like aggression, digging, barking and howling problems. They suffer from stress and frustration. They can be annoying to neighbours and dangerous to visitors. When everyone leaves the house, the dog feels loneliness but also its territorial instinct tells him to guard the property. When chained up on top of this, it can feel doubly reactive (and behave accordingly), as it cannot do the job it wants to do. They are too hot in the summer, too cold in the winter, sometimes lack adequate shelter and fresh water, and are often dirty and ungroomed. When dirty, though no fault of their own, they are also again less likely to make it indoors.
Please don't get a dog, large or small, unless you are prepared to let him live with you in the house. This means investing time in housetraining, chewtraining, daily walks, and teaching good manners. It also means buying appropriate toys for them to chew and burn energy.
If you would like to leave your dog in the yard for part of the day when you're gone, make sure the fence is visually opaque so that he is not teased by the sight of passersby or tormented by kids. Leave him chew toys, proper shelter and fresh water. Bring him in when you're home and provide daily walks.
Being outside in the yard does not count as "exercise." Your dog would rather spend a little time with you than have a football field to play in alone. They won't exercise themselves. That's your job.