The inherent energy and drive that was part of their temperament was channeled into their work. Energy was needed to perform functional tasks. Breeds, once valued for their working ability, now find themselves in situations where they have no opportunity to use up their energy. Purebred dogs are often selected, with little research, as pets, purely because people like their appearance. Through indiscriminate breeding their bloodlines work their way into many of the mixed breeds we see at shelters and rescue agencies.
Many dogs still exhibit the energy that contributed to the form and function of their breed.
When cared for properly, these dogs do well. When left isolated for long periods of time, these types of dogs become desperate for social interaction and behave in an uncontrollable ways. They commonly develop destructive habits as a release mechanism for their frustration. The more ill mannered the dog becomes, the less pleasant it is to be around the dog. The less pleasant the dog is to be around, the less socialization the dog gets.