Research roundup: Animal-assisted therapy

This issue addresses the use of animals as a therapeutic agent in reducing aggressive behaviors, anxiety, posttraumatic stress symptoms and attention-deficit/hyperactivity disorder in a variety of inpatient and outpatient settings.

Animal-assisted therapy (AAT) encompasses the use of animals, typically dogs or horses, in providing therapeutic services for a broad range of psychological disorders. From the U.S. Department of Veterans Affairs to pediatric hospitals across America, the presence of service animals is becoming more prevalent. Therefore, it is useful for practitioners to be familiar with  the efficacy and potential benefits of AAT. 

The following studies investigated the use of animals as a therapeutic agent in reducing aggressive behaviors, anxiety, posttraumatic stress symptoms (PTSD) and attention-deficit/hyperactivity disorder (ADHD) in a variety of inpatient and outpatient settings. Under the direction of a trained professional, individuals completed structured tasks with a certified animal during therapy sessions. Although the simple presence of an animal in a therapeutic setting may have positive implications, often referred to as animal-assisted activated, the following studies followed specific treatment protocols, which relied on goal-directed interventions.

Earles, J. L., Vernon, L. L., & Yetz, J. P. (2015). Equine‐assisted therapy for anxiety and posttraumatic stress symptoms. Journal of Traumatic Stress, 28(2), 149-152. Doi 10.1002/jts.21990. 

Nurenberg, J. R., Schleifer, S. J., Shaffer, T. M., Yellin, M., Desai, P. J., Amin, R., ... & Montalvo, C. (2015). Animal-assisted therapy with chronic psychiatric inpatients: Equine-assisted psychotherapy and aggressive behavior. Psychiatric Services, 66, 80-86. Doi 10.1176/

Schuck, S. E., Emmerson, N. A., Fine, A. H., & Lakes, K. D. (2015). Canine-assisted therapy for children with ADHD: Preliminary findings from The Positive Assertive Cooperative Kids Study. Journal of Attention Disorders, 19(2), 125-137. Doi: 10.1177/1087054713502080.


Nurenberg et al. (2015) studied the use of equine- and canine-assisted psychotherapy in treating violent and aggressive behaviors in 90 hospitalized psychiatric patients. The majority of participants had diagnoses of schizophrenia or schizoaffective disorder and were involuntarily committed to the hospital. 

Patients were randomly assigned to one of four conditions: equine-assisted psychotherapy, canine-assisted psychotherapy, active control (such as a social skills group) or standard control. The equine-assisted psychotherapy followed the model of the Equine Assisted Growth and Learning Association, which involved trained therapists and credentialed therapy horses by the Delta Society/Pet Partners. Therapy sessions included reviewing safety skills, greeting the horses, and engaging in a discussion period and guided activities such as leading horses through an obstacle course. 

Canine-assisted psychotherapy utilized a similar, but more structured model that encompassed the use of certified therapist-dog teams, group therapy sessions, discussion sessions and guided activities such as grooming, leading and directing the animals. Pre- and post-measures of violent aggressive incidents were assessed and recorded by trained hospital staff who were blinded to group treatment assignment. 

Results showed that patients benefited from 10 weeks of equine- and canine-assisted therapy. Those who received equine-assisted therapy in particular displayed the most significant decrease in aggressive behavior. The unique effect of therapy horses may come from the animal’s physically imposing appearance and highly responsive nature. Trained equine animals can perceive a person’s nonverbal behavior and respond to changes in biochemistry, body language and voice inflections. They also mirror nonviolent behavioral strategies, which can aid humans in developing a higher tolerance for challenging interpersonal stimuli. In sum, the horse’s imposing stature and ability to respond to human stimuli, while mirroring nonviolent behaviors is believed to have helped the psychiatric patients to experience less affective symptoms and to have more improved interpersonal interactions. 

The effectiveness of equine-assisted therapy in reducing anxiety and PTSD symptoms was also studied by Earles et al. (2015). In this small naturalistic study, participants who experienced PTSD symptoms above 31 on the PTSD Checklist (PCL- S; Weathers, Litz, Herman, Huska, & Keane, 1993) engaged in tasks with horses for six weeks based on the Equine Partnering Naturally© program. During each weekly two hour session, the participants learned how to nonverbally interact with the animals, and to set boundaries, halter, lead and back up the horses. These activities were designed so that the horses provided immediate feedback on nonverbal behavior, such as by crowding a participant who is physically hunched over. This feedback increases participants’ nonjudgmental self-awareness, concentration and listening skills, which is hypothesized to subsequently reduce PTSD and anxiety symptoms.

Several questionnaires, such as the Trauma Emotion Questionnaire (Vernon, 2009), the Generalized Anxiety Disorder Scale (Spitzer Kroenke, Williams, & Lowe, 2006) and the Patient Health Questionnaire (PHQ-9; Kroenke, Spitzer & Williams, 2001), were used to assess physical, emotional and psychological health. After the completion of the equine-assisted therapy program, participants reportedly engaged in more mindfulness strategies, and experienced significantly reduced levels of PTSD, generalized anxiety, alcohol abuse and emotional responses to trauma. Participants also displayed lower levels of depression. 

Finally, Schuck et al. (2015) reported preliminary findings from Project Positive Assertive Cooperative Kids, an on-going randomized clinical study that explores the efficacy of canine-assisted therapy in treating children with ADHD. Participants were randomly assigned to receive 12 weeks of cognitive behavioral group therapy (CBGT) that either incorporated live therapy dogs or puppets. The intervention sessions occurred twice per week and included a social skills curriculum, parental training sessions, medication and structured activities like having the children read short stories to the dogs and training exercises. 

Parental reports of their children’s problem behaviors, social skills, and prosocial orientation were assessed prior to starting treatment and throughout the course of the study. Immediate and six weeks post-intervention assessments were also conducted with both the parents and children.

The preliminary results revealed that across both treatment groups, there was an overall reduction in ADHD symptoms. Those who participated in CBGT with a live therapy dog displayed a more significant improvement in social skills and prosocial behavior as well as a reduction in problematic behaviors when compared to those in the therapy group incorporating a puppet. The researchers suggested that the live animals — as opposed to the puppet — acted as a novel stimulus, which primed the children for the therapy sessions and allowed for them to maintain attention and refocus on the task at hand. 

Practical Implications

The three articles suggest that AAT may be an effective form of therapy for treating emotional and behavioral issues in patients experiencing anger, PTSD or ADHD. Dogs and horses have the potential to engage and serve difficult-to-engage populations. These articles suggest that animals provide a significant calming and therapeutic effect on patients with psychological disorders.

For the type of programs summarized here, proper training and certifications from accredited programs should be acquired. Yet, clinicians may want to consider how incorporating the use of animals, such as by bringing a dog into the therapy session, may help patients increase attention, reduce anxiety and combat unwanted behaviors. However, veterinary considerations, infectious control policies and liability concerns should also be taken into account, and we encourage psychologists to comprehensively explore additional resources to determine how the incorporation of therapy animals may be useful in their practice.