Dysfunctional Owners

Unintentional Owners
Most thought of the pet as a temporary guest. They were keeping the animal until they could find it a good home. Were not seeking a pet but acquiesced when petitioned by other people or an orphaned animal came into their life.
Nonconsenting Ownership
No consensus on owning and caring for the pet by everyone in the household. When attachment is not shared, indifferent family members quickly become intolerant of annoying behaviors and the pet becomes expendable.
Incompatible Matches
Temperament, size, grooming, energy level and personality problems. Also, children conflicted with the pet.
Time Constraints
Adult attachment depends, in part, on the time and energy available to the adult and the amount of nurturing required by the pet(s). (Kidd, Kidd & George) Time constraints were often realized after the pet was obtained. Owners are tired when they come home from work and often cannot exercise, groom or play with the pet. (Dogs experience pet-up pet energy that is not expelled, causing hyperactivity and other behavior problems.) Dogs, primarily larger breeds, are kept alone in the backyard. Boredom ensues for poor social interaction and the animal takes to roaming.
Regular duties, like walking the dog, became time consuming and difficult, especially for children. Human interaction with pets has decreased do to more work, household and parental demands on individuals time.
Health Problems
Allergies/health problems forces the owner to relinquish.
Unfulfilled Expectations
Owners become disappointed when the reality of the pet doesn't live up to the dream. Major areas are cute puppies that turn into uncontrollable big dogs with attitudes, dogs that will teach responsibility to children (parents teach responsibility to children using dog care as an example), gift pets that are not wanted after the newness wears off.
External Pressures
Landlord objects. (Fewer apartments and condominiums where pets are not accepted.) Animal behaves negatively to people outside the family (neighbor complaints, animal control impoundment, etc.)
Stage-of-Life
Pets can play different roles in their owner's lives at different stages of life. Our involvement with pets, in particular dogs, expands and contracts as we move through phases of the family lifecycle. Thus, a pet may be acquired as a teaching aid for children and end up as a companion, or be bought as a watchdog when, in fact, it becomes a child substitute. The relationship between an owner and their pet(s) is, thus, not static and it can be influenced by the personality of the animal as well. Personal life changes effect pet relationships like, new baby, divorce, marriage, death, kids going away to school, new home, ability to travel ("pets tie you down")
Consider Pets as Livestock
Some owners (usually from rural areas) see companion animals as livestock and peripheral to their homes and lives. They are outside animals, with low social interaction and little training. (Often these animals are intact and roam.)
Guard Dog Mentality
People, paranoid about crime, acquire dogs for protection — obtained not for companionship but to guard the property and scare-off intruders. Usually, the dog obtains no house manners and, do to poor training methods, becomes hard to control and aggressive. The unwittingly abused animal is soon cast off.
Heartache
Distress caused by the loss of a pet that was loved and died. Owners are hesitant to replace them.