In a natural environment the dog is a pack animal. When we bring a puppy into a human family the puppy naturally becomes part of a new pack—his adoptive human family. Unfortunately, the modern family is always on the go, and the new puppy is often left alone for long periods of time. It's unnatural for a dog to be isolated from his pack. The stress associated with isolation from the nuclear family can lead to a syndrome described as "Separation Anxiety."

The most common clinical sign of separation anxiety is vocalization—barking, whining, or whimpering. Additional symptoms include trembling, destructive behavior such as chewing or digging, house soiling, salivation, vomiting, diarrhea, anorexia and depression. The dog is often so stressed that he will be unable to settle down. Symptoms are often most severe during the first 15 to 20 minutes of separation.

Separation anxiety may set in when the pet is stressed and unable to cope after major changes in his or her life, such as moving to a new home, or having a family member exit their life—such as a student leaving for college or a family member passing away. Changes in family routine may also induce stress. For example, family members that are home for the summer leaving in the fall for greater periods of time to attend school or a stay-at-home caretaker taking a job outside the home. Stress may also be induced by a companion pet suddenly being absent.

Current research indicates a direct association between thunderstorm and noise associated phobias and separation anxiety. Fireworks and thunder may cause clinical signs of separation anxiety to be exhibited.

A dog may be confined to a kennel to minimize destructive behavior but this does not address the core problem. Having dogs or other pets in the home will often reduce the incidence of separation anxiety due to the companionship of other pack members. Since the response is anxiety produced, punishment will not be effective and may further aggravate the problem eventually disrupting the human-animal bond. Various drugs are now available for the treatment of separation anxiety; Novartis markets a tricyclic antidepressant Clomicalm® and Lilly has recently released Reconcile® which is a serotonin reuptake inhibitor. Both of these drugs are specifically marketed for use in the treatment of separation anxiety and are often used to treat noise phobias as well. Lilly Animal Health estimates the up to 17 percent of the dogs in the United States suffer from separation anxiety.

Chemical treatment of separation anxiety is most effective when combined with behavior modification. The dog needs something to do while the family is absent. Dogs are happiest when they are given a job or have something to occupy their time. Kong toys stuffed with treats and peanut butter or flavored Kong paste will give a dog a pacifier of sorts. Other dogs may show less signs of anxiety when allowed to patrol the yard rather than being confined to a kennel. Separation anxiety is unheard of in a Border Collie that herds sheep for a living but may commonly be seen in a lone Golden Retriever that lives in an small city apartment or condo.