In 1857 British novelist George Eliot wrote, “Animals are such agreeable friends. They ask no questions and they pass no criticism.” So it is no surprise that scholars have long been intrigued by the possibility that animals possess largely untapped therapeutic powers. But are animals good for our psychological and physical health, either as pets or as “therapists”?

Most Americans are animal lovers; about 63 percent of U.S. households contain one or more pets, according to the American Pet Products Manufacturers Association. Several, but not all, studies suggest that those of us who own pets tend to be somewhat happier than those of us who do not. In addition, research by Erika Friedmann and her colleagues at the University of Maryland School of Nurs­ing shows that pet ownership predicts one-year survival rates among victims of heart attacks.

Though interesting and potentially important, studies such as these are difficult to interpret because pet owners may differ in unmeasured ways from people who do not own pets. For example, pet owners may be better adjusted psychologically and have fewer cardiac risk factors (they may eat healthier diets and experience lower levels of hostility) than non–pet owners.

Easing Stress?
To unravel the potential influences of pets on well-being, researchers must conduct experiments that randomly assign some people, but not others, to receive a pet, either in the laboratory or in their home. Studies by psychologists Karen Allen of the University at Buffalo and James Blascovich of the University of California, Santa Barbara,  and their colleagues demonstrate that the presence of a favorite pet during a stressful task—such as performing difficult mental arithmetic—largely prevents spikes in participants’ blood pressure. In contrast, the presence of a friend does not. In addition, Allen’s work shows that stressed-out, hypertensive stockbrokers who were randomly assigned to adopt either a pet dog or cat ended up with lower blood pressure than those who were not. These studies suggest that the presence of pets may lower our blood pressure and stress levels, although they do not tell us the reasons for this effect. They also do not inform us whether we would observe similar effects with other preferred stimuli, such as a good luck charm or a favorite doll.

Few would contest the claim that pets can give us comfort, especially in times of strain or loneliness. A far more controversial question concerns the effectiveness of animal-assisted therapy (AAT), defined as the use of an animal as either a treatment by itself or an addition to an existing treatment, such as psychotherapy. The animals used in various forms of AAT are a veritable menagerie: horses, dogs, cats, rabbits, birds, fish, guinea pigs and, perhaps best known of all, dolphins. In turn, the psychological problems for which AATs are used include schizophrenia, clinical depression, anxiety disorders, eating disorders, attention-deficit hyperactivity disorder, autism and a host of developmental disabilities.

Popularized largely by Yeshiva University psychologist Boris Levinson in the 1960s, AATs appear to be surprisingly common: a 1973 survey by Oklahoma State University psychologist Susan S. Rice and her colleagues revealed that 21 percent of therapists in the psychotherapy division of the American Psychological Association incorporated animals into their treatment in some fashion. Whether this percentage has changed in 35 years is unknown.

Leisure vs. Therapy
Do AATs work? To make some inroads into this question, we need to distinguish between two different uses of animals: recreation and psychotherapy. Some uses of animals are purely recreational: their goal is to allow their human companions to have fun. There is scant dispute that interacting with friendly animals can “work” for such purposes, because such activities often make people feel happier temporarily. To show that AATs work, however, researchers must demonstrate that animals produce enduring effects on people’s psychological health, not merely short-term changes in mood, such as pleasure, relaxation or excitement.