Depression is a serious illness that affects more than 20 million people in the United States. Depression is a mental illness involving the brain. It is more than simply feeling sad for a few days. Symptoms may include sadness, loss of interest or enjoyment in activities, energy loss, and/or thoughts of suicide. These symptoms persist for weeks or months at a time and interfere with everyday life. Several factors can make some people more likely to develop depression including genetic history, brain chemistry, and stress such as loss of a loved one or relationship troubles.
There are many ways to treat depression including therapy and medication. Recently, scientifically controlled treatments are being explored by researchers studying the human-animal bond. Animals are often a source of comfort and support in a person’s life. Pets are more than just possessions; they are part of the family.Pets are capable of offering loving companionship and interaction, especially when their owners may feel cut off from everyone else. As noted in other areas of research, animals also make a patient feel more comfortable during therapy settings. The animal does not judge, but accept the person who may feel neglected.
Investigation into the benefits of the human-animal bond for those suffering from depression is not a new phenomenon. A number of experiments have been carried out and studies have described the benefits of interaction with animals. However, due to the varied nature of these programs, participants, and durations the results are not always consistent and paint a mixed picture.
State of Current Research
Researchers, in response to the mixed results obtained from earlier studies, have conducted new studies into the human-animal bond and its effect on depression. Researchers believe that they have demonstrated the benefits of animal-assisted activities and animal-assisted therapy. Using standardized methods and commonly used analysis tools new evidence supports the theory that animal interaction lessons the symptoms of anxiety and depression.
There are many tests for measuring the symptoms of depression and anxiety. Two tests in particular are commonly are frequently used in the sampled studies. The Beck Depression Inventory (BDI) is a 21-item self-report test a patient uses to provide information about how he/she is feeling . The Beck Anxiety Inventory (BAI) is also a 21-time self-report test, like the BDI. It is used to measure anxiety. Both tests are extensively used in researching depression and anxiety disorders.
Souder and Miller (2007) conduct an overview of animal assisted therapy (AAT) and less clinical animal assisted activity (AAA)approaches in order to see if there are, in fact, benefits in the treatment of depression and anxiety. The researchers found that while potential benefits are well catalogued, the “research lacks the methodological leverage to make clear inferences about AAA/AAT effects”. They therefore conducted a meta-analysis, a study of studies, to find trials that meet a list of criteria for scientific rigor that demonstrate the effectiveness of AAA/AAT interventions. Five studies were selected for their ability to meet the criteria: inclusion of a control group; random assignment; exposure to AAA or AAT; and some measure of the depressive symptoms, such as BDI. Much of their article defines the methods used to compare finds across the studies.
The meta-analysis of these five trials indicated “that exposure to AAA/AAT produces significant improvement in depression, as measured with a range of well-accepted instruments”. The next question raised was how effective a patient can expect AAA/AAT to be. A patient undergoing AAA/AAT should not expect dramatic decreases in depression. However, the patient is likely to feel very real and noticeable relief. The authors believe that the positive findings of the meta-analysis lend support for utilizing AAA/AAT in treatment of anxiety and depression. Beyond being an interesting theoretical question, the benefits of AAA/AAT have been demonstrated in a practical, working therapy setting.
Marieana Le Roux and Kemp conducted a study of the impact of AAA on residents of a long term-care facility, such as a nursing home. It has been reported that residents of a long-term care facility may suffer depression symptoms and boredom. In the background to their article, the authors reference other studies that report significant decreases in depression symptoms, fatigue, and confusion among elderly residents. Interaction with animals can help residents be more social with each other as well. In their study, an experimental group received 30-minute visitations once a week from a ‘Pets as Therapy’ dog and its handler for six weeks. A control group had no interaction with the dog until after the study was completed. At the beginning of the trial, the control and experimental group had no significant differences between their BDI and BAI scores. The experimental group reported significant decreases in their depression symptoms while there was no significant different between pre and post BDI scores for the control group.
While many studies focus on house pets, dogs specifically, the use of animals in therapy settings is not restricted to traditional house pets. Berget et al. (2011) describe a study in which patients interact with farm animals instead of dogs or cats. Under the supervision of volunteer farmers and therapist aid, the patients were taught how to care for the farm animals. After the trial had been completed, the treatment group reported a significant decrease in depression. Anxiety also decreased in a follow-up evaulation after the trial for the experimental group, but not for the control group. After regression analysis, patients with the highest BAI scores appeared to have profited the most from the animal interactions. The authors conclude that there is no reason to exclude patients with mood disorders or adult personality disorders from long-term treatment with farm animals.
The authors offer two explanations for why the decrease in anxiety was reported six months after the trial instead of right at the end. The first explanation is that the patients learned new skills and that doing so gave them more self-confidence. Secondly, learning to have positive social interactions with the animals might have made the participants less fearful of social interaction. These hypotheses are supported by an earlier study done in 2008 by the same authors. In the 2008 study they focused on a psychiatric patient’s self-efficacy and coping ability after a controlled intervention with farm animals. Patients in the experimental group reported both higher self-efficacy and coping ability after AAA with the farm animals.
Areas for Future Investigation
Using large animal-assisted activities could be useful in occupational therapy. Instead of psychotherapy, or talk therapy, occupational therapy treats through actions. How feasible is incorporating large animal therapy, like farm animals, into an occupational therapy program? Could city programs make use of those programs, or even have access to farms? 
The pairing of a person and their companion animal is not inherently random. The person and the pet have a connection that has been shared for a significant length of time. How is randomization achieved for studies involving companion animals and depression? 
A concern often raised is that the trials and studies are too short to draw out differences. How might studies by adapted, or feasibly funded, to test long-term exposure to animal assisted therapy and activities? How might data tracking change, if at all? 
One concern raised with AAA/AAT is the degree to which contact with the human observer or facilitator may cloud the results. The person administering the therapy or in other ways having contact with the patient could obscure the measures of AAA/AAT effectiveness. In what ways might the effectiveness of human-animal interaction be isolated and more effectively measured? 
Is there a difference in the effectiveness of AAA/AAT on patients who once have owned pets and those who haven’t? 
Berget, B., Øivind, E., Pedersen, I., & Braastad, B. (2011). Animal-assisted therapy with farm animals for persons with psychiatric disorders: Effects on anxiety and depression, a randomized controlled trial. Occupational Therapy in Mental Health, 21(1), 50-64.
Berget et al.’s article describes a randomized controlled study of the effects of farm animals on individuals with a variety of psychiatric disorders. Farmers taught patients how to care for a variety of animals such as sheep, cows, pigs, and horses. The patient’s therapist or aide was always present while the farm work was taking place. A follow up meeting six months after the trial showed almost significant reduction in self reported depression and anxiety for patients involved in the animal-assisted therapy group. The author’s speculate that in addition to interaction with the animals and their caretakers, learning a new skill might have helped the patient’s later, and also that a pleasant social interaction with the animals had helped them engage with people outside of the intervention.
Le Roux, M. & Kemp, R. (2009). Effect of a companion dog on depression and anxiety levels of elderly residents in a long-term care facility. Psychogeriatrics, 9, 23-26.
Le Roux and Kemp’s study investigated the effect of a companion animal, dogs, on depression and anxiety levels of residents in a nursing home. The experimental group received 30 minutes of animal-assisted activities (AAA) once a week for six weeks. The control group received no AAA treatment. At the beginning of the trial there were no significant difference between the BDI and BAI scores of the control and experimental groups. After the study, there was a significant difference in the depression scores, the experimental group showing positive symptom reduction, but not a statistically significant difference in the anxiety scores.
Souder, M. & Miller, M. (2007). Do animal-assisted activities effectively treat depression? A meta-analysis. Anthrozoos, 20(2), 167-180.
Souder and Miller’s article is a meta-analysis of the state of studies on the relationship between animal-assisted interventions and depression. They select five studies that meet scientific research design criteria. Sounder and Miller conclude that these studies show statistically significant gains made by animal-assisted activities (AAA) and animal-assisted therapy (AAT) interventions on treating for depression. Souder and Miller also provide recommendations for ways to correctly investigate the impact of the human/animal bond on depression.
^ a b c d Berget, B., Øivind, E., Pedersen, I., & Braastad, B. (2011). Animal-assisted therapy with farm animals for persons with psychiatric disorders: Effects on anxiety and depression, a randomized controlled trial. Occupational Therapy in Mental Health. 21(1). 50-64.
^ Berget, B., Øivind, E., & Braastad, B. (2008). Animal-assisted therapy with farm animals for persons with psychiatric disorders: Effects on self-efficacy, coping ability and quality of life, a randomized controlled trial. Clinical Practice and Epidemiology in Mental Health. 4(9). Retrived from: http://w01.biomedcentral.com/1745-0179/content/4/1/9/