Left outside, most dogs will develop a barking problem. Excessive barking is largely self-reinforcing and, once established, can be very difficult to ameliorate as long as the dog remains outside. Many dogs will develop a digging habit when left unsupervised in the yard. Digging can also be highly self-reinforcing and resistant to attempts at extinction. Destructive chewing is another behavior problem that can develop in dogs left outside.
Adult dogs chew mainly to relieve anxiety or boredom, or simply for enjoyment.
Like barking and digging, chewing is a natural canine activity that we can anticipate and channel. A host of other problems are associated with outdoor confinement. The fence itself may intensify any underlying territorial aggression in susceptible dogs. The dog left outside may be subject to cruel or thoughtless behavior on the part of humans, with long-term behavioral consequences, or may be exposed to wild or stray animals, which can transmit parasites and disease. Outside dogs can develop storm phobias and are at risk of hypothermia and heatstroke.