Improving Engagement in Behavioral and Mental Health Services Through Animal-Assisted Interventions: A Scoping Review

Client engagement in behavioral and mental health services has been strongly linked to higher clinical functioning, improved outcomes, and treatment completion (1–3). Interventions that increase engagement and encourage clients to participate fully in treatment are likely to be a powerful tool to prevent mental illnesses and increase clinicians’ abilities to intervene at an early stage of illness. In mental health and addiction services, interventions or factors known to improve engagement include motivational interviewing (4), the client-therapist relationship (5), practitioner behaviors (6, 7), perceived usefulness of the treatment (8), and incentives such as monetary compensations (9, 10). Interest has been growing in the use of animal-assisted interventions (AAIs) in various mental and behavioral health service settings to improve client engagement. For example, a dog might be incorporated into individual therapy to provide a reassuring presence and opportunity for tactile soothing (i.e., through petting) to support a client’s sense of safety or ability to process difficult emotions. Alternatively, a session may involve client interactions with a horse to facilitate discussion of personal boundaries and communication using observation of the horse’s responses to the client or other environmental stimuli. Some research has measured the proximal and distal effects of AAIs on clinically relevant outcomes (11, 12). However, to date, no scoping review has been conducted to assess the state of the existing literature and identify research considerations in the field of engagement specific to AAIs.

AAI is defined as the intentional use of an animal to reach specified treatment goals and provide therapeutic benefits through a positive relationship between the client and the animal (13, 14). AAIs can occur in any setting, provided that one or more animals are used to reach a client’s specified treatment goals. Inclusion of animals by health or human service professionals is increasingly common and is associated with positive general medical and psychological benefits (14, 15). AAIs have been theorized to promote client engagement by enhancing the relationship between the client and the AAI practitioner, with some studies reporting increased direct social interaction between the client and practitioner in the presence of animals (16–18). Therapists who use animals in behavioral or mental health services may be perceived as less threatening, which can reduce barriers to client engagement (19), prompt clients to be more authentic and present (20, 21), boost clients’ sense of safety in the intervention space (22), and increase clients’ motivation to attend therapy sessions (23). A comprehensive, evidence-based understanding of how AAIs affect engagement in behavioral and mental health services is needed to optimize their clinical effects.

The concept of engagement is multifaceted, and different forms of engagement may be differentially affected by AAIs. Studies do not always specify which aspect of engagement is the focus of the intervention or research question. A diverse range of operational definitions and outcomes are used in existing research, and interventions target various facets of engagement (5). In this scoping review, client engagement was operationalized as a multifaceted construct that can refer to the client’s motivation, involvement, active participation, or attendance to the behavioral or mental health service that he or she is undergoing (5, 24, 25). Thus, engagement is indicated by the client actively, behaviorally, cognitively, or emotionally participating in the therapy process with the clinician or, if applicable, other participants in a service setting (2).

The purpose of this scoping review was to determine what is known about the use of animals to affect client engagement in behavioral and mental health services and synthesize the extant literature pertaining to this topic. Given that client engagement in behavioral and mental health services predicts health outcomes (1–3) and that the field of AAIs is rapidly expanding, a need exists for understanding intervention strategies that promote engagement so that evidence-based recommendations can be provided to policy makers, practitioners, and researchers to optimize their implementation. We therefore sought to identify the existing knowledge base to inform future research and practice in these areas.

Methods

Scoping review methods are most appropriate when the aim is to assess the prevalence of existing evidence or identify key concepts, or when the topic is being reviewed for the first time (26), as was the case for this review. A scoping review of quantitative, qualitative, and mixed-methods research was conducted in accordance with Arksey and O’Malley’s (26) five-stage framework: identifying the review question; identifying relevant studies; study selection; charting the data; and collating, summarizing, and reporting the results. We also followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA ScR) checklist (27). These two methods were adopted for their rigorous and transparent processes, allowing for replication of the search strategy and verification of the reliability of the study findings.

Review Question

The review questions were developed through discussion among research team members engaged in human-animal interaction research and direct clinical practice. Our focus was to assess the prevalence of existing evidence of the ability of AAIs to improve engagement in behavioral and mental health services. Because AAIs are currently used as an adjunct to standard care with many age groups, diagnoses, and types of treatment, the review questions were kept intentionally broad to identify the full breadth of work being done in this area. This supported the review objective to identify initial knowledge that may be associated with the use of AAIs for client engagement to inform future research.

The following review questions were posed to ensure a comprehensive assessment of the existing scientific literature. What research has been completed regarding the use of animals to affect client engagement, including measurement of potential mechanisms or processes of change? How have interventions that use animals been structured and protocolized? How is engagement operationally defined by these studies?

Relevant Studies

We developed an a priori search strategy to widely cover the relevant literature on the key concepts related to the review questions. The review of the literature was completed over 2 months, ending in May 2019. The following electronic databases were searched: PsycINFO, EBSCOHost, Social Services Abstracts, Sociological Abstracts, Proquest, ERIC, JSTOR, SAGE, Applied Social Sciences Index and Abstracts, Wiley, Campbell Collaboration, and Cochrane. Content experts on the research team (E.F., A.G.Z.) worked in consultation with a social sciences librarian to develop a search strategy by using concepts and keywords to describe behavioral and mental health services, engagement, and AAIs. Key words were searched within three groups using the conjunction “OR,” and the groups were combined with “AND.” In line with current conceptualizations of engagement (24), the term groupings included “engagement,” “involvement,” “attendance,” “participation,” and “motivation.” AAI-related search terms included “animal-assisted,” “animal therapy,” “animal intervention,” and “animal facilitated.”

Last, mental health services were defined as the assessment and treatment of an individual or group by a professional to alleviate mental or emotional symptoms or psychiatric conditions (28). Behavioral health services were defined as the promotion of mental health, resilience, and well-being and the treatment of substance use disorders (29). Search terms included “mental health,” “therapy,” “treatment,” and “counseling.” Inclusion and exclusion criteria for this search were formulated to account for the presumed scarcity of research in this topic area while being as comprehensive as possible to aid in the identification of primary evidence pertaining to the use of AAIs to promote engagement (Table 1). A review protocol for this study is available on request from the corresponding author (K.N.M.).

Study Selection

A two-stage study screening process was used. First, duplicates of articles were removed, and then a single reviewer (A.G.Z.) screened the titles and abstracts of the results, applying the inclusion and exclusion criteria and removing articles that were ineligible. Next, the same reviewer reviewed the full text of the remaining articles to assess whether they met the inclusion criteria. Articles for which it remained unclear whether they met the inclusion criteria were discussed by the full team.

Data Extraction and Charting

Studies selected for inclusion were charted (26). The reviewers extracted the first author; year of publication; study design; sample size; a description of the intervention(s), characteristics, structure, and any associated protocols; and engagement outcomes measured. Findings were synthesized, documenting overlap and differences in research methods and results, intervention approaches, and definitions of engagement.

Results

Article Selection

The initial electronic search yielded 1,521 original records. After removal of 178 duplicates, title and abstract screening eliminated another 1,311 articles because the interventions did not target mental or behavioral health outcomes, live domesticated animals were not included in service provision, or no English version of the publication was available. Thirty-two articles remained for full-text screening. Of those, 22 articles were excluded because of their use of nondomesticated animals (e.g., dolphin-assisted interventions), use of nonliving animals, or lack of engagement-related outcomes. Ten articles were selected for this scoping review on the basis of the inclusion criteria. (A PRISMA diagram is available in an online supplement to this article.) Of the articles included in this review, two were published between 2000 and 2009, and eight were published between 2010 and 2019 (Table 2) (30–39).

Study Methods and Findings

The 10 studies had a wide range of foci and methods. The methods used to ascertain whether AAIs affected client engagement included three phenomenological qualitative analyses, two case studies with observational data, one systematic review of broad clinical goals for canine-assisted psychotherapy that included the outcome of engagement, two behavioral observation studies, and two randomized controlled trials (RCTs) that used validated measures to assess engagement. The studies were conducted for clients ages 3–54 years who were deemed “at risk” or who were being treated for conditions including depression, posttraumatic stress disorder, autism spectrum disorder, pervasive developmental disorders, and substance dependency; clients were treated in a wide variety of settings, including clinical therapy offices, residential treatment facilities, and prisons. Overall, the identified articles illustrated a trend in AAIs emerging as a conceptually important and effective tool to improve engagement among persons seeking behavioral or mental health services. Findings within these studies that were germane to the three review questions were identified.

What research has been completed regarding the use of animals to affect client engagement, including measurement of potential mechanisms or processes of change?

In the 10 research studies, changes in client engagement in a behavioral or mental health services when AAIs were used were measured as either the primary or secondary reported outcomes (30–39). Phenomenological qualitative data collection used in three studies consisted of 25 semistructured, in-person interviews ranging from 10 to 45 minutes (30–32) and, in one study, written reflective prompts (31). In these studies, data were analyzed with a structured modality of data analysis, such as Moustakas’ (40) transcendental phenomenological model (30, 32), or a conventional content analysis approach, as described by Hsieh and Shannon (41). The two research groups that used case study designs conducted observations and collected data before and after interventions by asking the participants to reflect on the intervention during interviews (34, 37). In one of these studies, significant statements regarding level of engagement were selected from the observations (37). One study conducted a systematic review of the use of dogs to increase adolescent engagement during psychotherapy and followed the PRISMA guidelines (35). Two studies used behavioral observation methods by videotaping AAI sessions with the clients and coding engagement behaviors during therapy sessions (36, 39). Only two studies were designed as RCTs (33, 38); one utilized the validated Session Engagement Questionnaire to measure each client’s level of engagement during an AAI (33), and the other used the Helping Alliance Questionnaire and the Session Rating Scale to measure therapeutic alliance as a proxy for client engagement (38).

Some evidence indicates that AAIs can positively affect client engagement. Studied outcomes include an observed increase in clients’ contributions to their therapeutic communities (32, 34); measured improvements to clients’ therapeutic alliance (38); increases in prosocial behaviors; active participation when interacting with a therapist (31, 34–36, 39); higher levels of motivation to attend therapy (30, 31); and improvement in clients’ engagement, attitudes, and behaviors in other, nontherapeutic activities (37). One study found no significant differences in engagement between groups with and without an AAI component (33). Several reviews noted a need for further research to identify mechanisms of change in AAIs because no agreed-upon theory of change currently exists (30–33, 35, 37). Two articles discussed potential mechanisms of change and identified these as the participant connection with the animal (32, 37), the context of where the intervention was conducted, and the staff conducting the intervention (37). No effects on the animals included in therapy were studied.

How have interventions that use animals been structured and protocolized?

The AAIs described in the 10 publications primarily used one or more dogs (30–36, 38, 39); only one study used horses (37). Several of the dogs included in these studies were accredited by a national or international therapy organization (31, 33–35, 38, 39) or had previously passed a behavioral test, such as the American Kennel Club’s Canine Good Citizen Test (31, 36). The other animals were not registered or did not have accreditation or testing status with a verified source (30, 33, 37). The structure and delivery of these AAIs in mental health service settings consisted of both individual (31, 33, 36, 37, 39) and group therapy sessions (30, 32, 34, 38). These AAI sessions occurred every 2 weeks (34), weekly (30, 33, 34, 37–39), or several times throughout the week (32, 35). For those studies that reported duration of AAI treatments, the range was between 5 and 15 weeks (30, 33, 34, 36, 37). AAIs were delivered by licensed psychologists (31, 33, 39), master’s-level clinical social workers (30), professional clinical counselors (38), and animal handlers who were trained to work with their specific animals (32, 34, 37, 39). Interactions between clients and animals were not forced by any group, and each participant was always given the option to interact or not with the animal (30–39). Intervention protocols were used in several studies that outlined specific safety guidelines for the animals and human interaction (33, 34). Protocols also discussed approved activities for which the animals in the interventions would be utilized, including general interaction activities such as petting or holding (30, 33, 34, 36, 38, 39), care tasks such as grooming or nail trimming (30, 37), discussion of an animal as a model for concepts such as boundaries (34, 38), or teaching general horsemanship (37).

How is engagement operationally defined by these studies?

Engagement as a construct in the therapeutic context was discussed as being an important component to client motivation, clinical outcomes, recovery, and reduction of recidivism rates across all 10 of the reviewed studies (30–39). However, no articles precisely defined or clearly operationalized this term. Generally, the studies alluded to the construct of engagement as meaning a client’s willingness to interact with the therapist, treatment, and setting during a single therapeutic session or for the duration of their therapeutic process (30–39). Two studies associated engagement with prosocial behaviors such as talking, demonstrating affection, and showing awareness of one’s social environment (35, 36). Three studies conceptualized engagement as motivation to attend and participate in therapy (31–33). Another used the term to discuss attitudes and behaviors in other aspects of clients’ lives, such as engagement toward attending school, in addition to actions and emotional and cognitive attitudes toward the behavioral or mental health service (37).

Although almost all of the studies found that AAIs positively affected client engagement, the inconsistent and often unclear definitions of engagement, the variety of study foci and research methods, and the paucity of rigorous methodological approaches all limited the reliability of this preliminary positive conclusion. The most common finding, that AAIs increase prosocial behaviors and active participation in therapy (34–36, 39, 41), aligned with the results of one of the two RCTs, which found that AAIs improve the therapeutic alliance (38). However, the other RCT found no significant differences with or without an AAI (33), further calling into question the overall strength of the available evidence.

Discussion

There is emerging interest in the use of animals to increase client engagement in therapy, both nationally and internationally. The findings of this review confirmed that interventions and research in this area remain limited and are focused on various facets of engagement. There remains a lack of studies that have used rigorous methods that might elucidate the effects of AAIs on engagement or underlying mechanisms of change. The very modest body of work in this area suggests that the use of animals to promote engagement has been largely overlooked. This is especially apparent when compared with the extensive and growing body of AAI research. AAI studies represented in this scoping review were delivered across a range of treatment settings, including private offices, residential treatment, and prison settings. It is clear that AAIs have used multifaceted conceptualizations of engagement, in part to adapt the intervention to be well suited to different types of treatment contexts and in a wide range of clinical populations, including youths on the autism spectrum, men with substance misuse issues, and incarcerated women. Although these initial indications that AAIs may represent a highly versatile intervention to increase client engagement, it remains unclear whether true effects exist, which intervention factors may be most relevant to maximize efficacy, and whether mechanisms of change or outcomes vary for different populations. Only three studies specified which facet of engagement was their focus (31, 33, 37); as for the remaining studies, the lack of clarification regarding which aspects of engagement were their focus left unclear exactly which variables were being measured and whether accurate measurement was achieved. Future research on the topic of the potential effects of AAIs on clinical engagement should make clear which facet of engagement is the focus of the study and how it is operationalized to reduce ambiguity in the findings.

That most interventions used dogs, with horses being the only other animal incorporated, may be related to a lower cost and fewer infrastructure requirements associated with dogs. This preference for dogs and horses is reflected in other AAI literature that commonly references use of these species but overlooks other companion animals (e.g., guinea pigs) that may also be well suited to this type of intervention. However, the studies lacked detailed information about intervention protocols, animal selection, handler and animal certifications, implementation considerations, indications and contraindications for clients who may be candidates for AAIs, animal welfare considerations, and safety precautions. This raises important questions regarding the ability of practitioners to implement these interventions ethically and with fidelity. This field of research would benefit greatly from future research providing greater specificity on these elements of AAIs, including clear protocols and guidelines for practice that promotes both human and animal welfare.

This review was limited by the amount and quality of the research available and by its focus on only studies available in English. The scoping literature review method did not include analyses of data quality or effect sizes (i.e., meta-analyses) and therefore did not substantively address the efficacy of AAIs for increasing engagement or factors that may drive this potential effect. Despite these limitations, the findings of this review suggest that AAIs may be a versatile approach to increasing client engagement for a wide range of client populations, but more research and better protocolization of these interventions are needed.

Conclusions

The findings of this review indicate that dogs were most commonly incorporated into AAIs, followed by horses. Preliminary anecdotal and observational evidence suggests that AAI benefit client engagement during a behavioral or mental health service visit. However, these findings should be viewed with caution, because it remains unclear for which clients the inclusion of animals may or may not be beneficial and why.