Equine-assisted interventions for veterans with posttraumatic stress disorder: a systematic review

Equine-assisted intervention therapy has a nearly 60-year history and has been shown to have a significant positive impact on various types of psychotherapy patients. Due to an increase in research on EAT, the number of existing methods of equine-assisted intervention therapy has gradually increased. Based on existing literature on the application of equine-assisted intervention therapy on veterans with post-traumatic stress disorder (PTSD), this study examines the characteristics of several types of equine interventions and includes a systematic review of peer-reviewed literature on equine-assisted interventions for veterans with PTSD published over the past 5 years, from 2018 to the present. Ten articles met the review criteria and served as the primary data for analysis. Several types of equine-assisted interventions were shown to have a beneficial psychological impact on veterans. However, some limitations were also found in the studies, such as that the majority of experiments were constrained by small sample sizes. Equine-assisted intervention therapy has been shown to be effective, but further research is merited, in order to focus on the specific details and theories involved in equine-assisted interventions, and on the welfare of the horses involved in the therapy.

1. Introduction

Danish dressage rider Lis Hartel is credited with being the inspiration behind the field of therapeutic horse riding. She won a silver medal in Grand Prix dressage at the 1952 Olympics in Helsinki, Finland, despite being severely disabled by polio. As a result of this amazing achievement, medical and equine specialists in Europe began offering therapeutic riding programs at their facilities (1). The research into equine-assisted healing began in 1960 and spans more than six decades. The use of horses in therapy is growing and is considered a viable option for treating a wide range of mental health disorders (2).

According to reports in the available literature, there are 600 equine-assisted intervention programs used by the Equine-Assisted Growth and Learning Association (EAGALA) (3). Equine interventions have grown in popularity over the years (4). Up until the present, equine-assisted intervention therapy research addressing a variety of mental health problems, including post-traumatic stress disorder (PTSD), has been limited and often poorly constructed, characterized by small sample sizes, unreliable assessments, unstandardized treatment techniques, and conflicts of interest among researchers.

The high risk of trauma that can result from combat, injury, captivity, and sexual assault faced by military personnel increases the prevalence of PTSD from 10% (civilian) to 30% (military personnel) (5–7). As research subjects, military personnel with PTSD play a critical role in the field of PTSD research. According to current research, the participation of horses in treatments has evolved into a novel auxiliary treatment method for a variety of diseases.

Therefore, in this study, we examine previous treatment cases with PTSD-afflicted veterans, in order to provide a theoretical and empirical foundation for the advancement of therapeutic horse engagement. More specifically, the main objectives of the paper are to describe the demographics of the veterans who participated in equine-assisted interventions and the screening processes that were used in their selection, as well as to describe the specific characteristics of equine-assisted interventions that have been applied to veterans, including intervention methods, study design, and results.

As previously mentioned, equine-assisted interventions have been an integral part of animal-human interaction therapy for 60 years. Despite the fact that recent systematic (8) and narrative review (9) have been conducted in this field, the present review introduces a more comprehensive analysis of the five distinct kinds of therapies. Also, this systematic review presents the treatment procedures for veterans in the form of a table, providing a more intuitive representation of the unique characteristics of each therapy.

The structure of the paper is the following: The first section presents an introduction to several different equine therapy methods. The second section gives the details of these methods and discusses the current state of equine therapy research for PTSD over a 5-year period.

1.1. Description of PTSD

According to the Diagnostic and Statistical Manual of Mental Disorders (DSM) (10), the diagnostic criteria for PTSD can include one or more of four domains: the re-experiencing (recurring thoughts or dreams) of traumatic events, avoidance (avoiding thoughts or feelings related to traumatic events), negative thoughts and moods (blaming oneself and/or others and having a pessimistic outlook), and anger arousal (outbursts of rage). In addition, significant functional impairment, varying psychiatric comorbidities, suicidal tendencies, substance abuse, chronic pain, poor physical health, and delayed seeking of treatment are all linked to the long-term effects of PTSD (11–13).

PTSD is a stress and trauma-related disorder, in which symptoms develop after exposure to one or more traumatic events (14). Reduced quality of life, substance abuse, suicide, risky and unhealthy behaviors, decreased productivity, domestic violence, and impaired relationships are all risks faced by people with PTSD (15). Traumatic neurosis (related to an individual’s vulnerability) is not the root cause of PTSD; rather, an external (traumatic) event triggers the disorder. The research of Gillies et al., Bradley et al., and Schneier et al. show that while some participants experienced an improvement of symptoms during treatment, others did not (16–18).

1.2. Animal assisted interventions

Animal-assisted therapy (AAT) is a therapeutic method that involves a patient, a therapist, and a trained animal, with the goal of achieving a predetermined therapeutic objective (19). Animal-assisted therapies (AATs) have proven effective in treating people of all ages, including those with both mental and physical impairments.

AAT has been utilized effectively as a treatment method for adults and children with psychological and physical disabilities. It is an adjunctive treatment designed to benefit the patient’s affective, cognitive, motor, and social functions (20). It has been demonstrated that AATs can improve communication, patient responsiveness, social interactive skills, socialization, activities of daily living, and general well-being (21).

Several different species of animals can be employed in AAT, with cats, dogs, and horses currently being the most common (22, 23). It is also important to note that AAT has been used successfully to help treat a variety of physical diseases. There is a significant amount of literature on the topic of using equine-based alternative activity interventions (AAIs) on people who have experienced trauma (24). Despite the widespread use of AATs, there have only been a small number of high-quality empirical studies that have examined their efficacy in the treatment of PTSD.

1.2.1. Equine-assisted interventions

Proponents of equine-assisted intervention argue that the therapeutic interactions between horses and humans can help patients gain new perspectives and alter their behavior by serving as catalysts for the emergence of new ideas and emotions. While the field of equine-assisted psychotherapy (EAP) is still in its infancy, there is substantial evidence in the literature supporting the use of AAT for people with trauma-related disorders. Some possible benefits are the development of nonverbal communication abilities through interaction with horses and a reduction of blood pressure, heart rate, and anxiety levels, and AAT can also effectively treat depression, anxiety, attention deficit/hyperactivity disorder, conduct disorder, dissociative disorder, Alzheimer’s disease, dementia, autism, and various other chronic mental illnesses (23–31).

1.2.2. Equine-assisted psychotherapy

EAP was established in 1990 and rapidly expanded in both Europe and the United States (32). EAP studies may always have limitations due to the variable nature of the intervention and the settings in which it is delivered, but rigorous randomized controlled trials are possible for evaluating EAP treatments (33).

EAP is similar to other AATs in that it is characterized by a lack of empirical evidence but includes many of the same components and benefits. EAP and AAT operate in different ways. First, dogs and cats are commonly employed for AAT because they are affectionate family pets. Horses are different from dogs and cats in that they are extremely sensitive to their environment and must be taught to trust humans. They are particularly sensitive to the moods and behaviors of the people around them (34). EAP has been shown to be a powerful and effective tool for participants who struggle with fear, depression, anger, anxiety, and other emotional disorders (35).

1.2.3. Equine-assisted activities and therapies

Over the past decade, the use of horses in the context of equine assisted activities and therapies (EAAT) has exploded in popularity, with over 66,000 children and adults (including over 6,200 veterans and active-duty military personnel) receiving assistance from one of the 800 certified member centers and 4,800 certified instructors (36).

Previous research in the field of EAAT has primarily been focused on physical rehabilitation, and the majority of peer-reviewed publications have reported on the effects of human-horse interaction (29, 37–41). The treatment programs focus primarily on riding horses, and several related areas of research have led to significant advances in the treatment of physical mobility disorders (42).

1.2.4. Equine-assisted therapy

EAT is gaining popularity as a complementary and alternative treatment for PTSD. EAT is also known as equine-facilitated cognitive behavioral therapy. There has not been sufficient research on the efficacy, feasibility, or safety of EAT in the treatment of PTSD, and there are no well-detailed treatment manuals for providing EAT. Therapeutic horseback riding (THR) and EAT-PTSD therapy, designed specifically for PTSD patients, are among the branches of EAT researched in the 10 articles used in this study. THR is a branch of EAT whose research focuses primarily on children with autism spectrum disorder (28). In addition, THR is an essential EAT technique.

However, THR should not be confused with hippotherapy, in which physical, occupational, and speech therapists specifically work with horses to improve the functional abilities of the patient (43). Through groundwork interaction and THR, bonding between the patient and the horse is facilitated (44).

1.2.5. Equine-assisted services

The term “equine-assisted services” (EAS) is used to describe a wide variety of AAIs designed to benefit human users (45). Due to the fact that EAS interventions are in the initial phases of scientific development, thorough investigations are generally insufficient, and there is no standardized intervention strategy, which causes difficulty in making comparisons and replicating studies (33). One of the 10 articles used in this study employed a new model of EAS intervention called Whispers with Horses (46).

2. Methods

This study presents a systematic review. Comprehensive searches were conducted in the US National Library of Medicine (PubMed, Bethesda, MD 20894, USA), Medical Literature Analysis and Retrieval System Online (MEDLINE), and Web of Science databases. These databases are renowned for containing articles of exceptional quality and reliability, offering robust bibliographic support. We identified original articles focused on horse therapy from the past 5 years, detailed by the search strategy in Table 1.

TABLE 1

Table 1. Searching strategy in databases.

A PRISMA flow diagram illustrating the search process is available (refer to Figure 1). The references from the selected studies were scrutinized to identify any additional pertinent articles. The most recent search for this systematic review was executed on 1 May 2023. There were no language restrictions.

FIGURE 1

Figure 1. Methodology of selected articles.

Considering the emerging nature of the topic and the limited data available, no filters were applied concerning the study design; hence, both longitudinal and cross-sectional studies were considered. Similarly, there was no age limitation for the study populations. Two researchers (JL and RS) independently and concurrently performed the search, screened the titles and abstracts of 85 retrieved articles, assessed the full texts, and finalized the selection. From this process, 10 articles met the inclusion criteria.

Inclusion criteria specified original studies evaluating the role of live horses in Psychologically-Assisted Therapy for Humans, excluding interventions using horse simulators. Reports, letters to the editor, and other systematic and narrative review articles were not considered. Ultimately, 10 articles were included based on these criteria.

3. Results

In this descriptive review, we consolidated our primary findings into five tables. Table 2 details the 10 included studies, accompanied by information regarding their respective participants. Of these, eight were conducted in the United States, one in Israel, and another in Australia.

TABLE 2

Table 2. Participates information.

Every veteran encompassed in the studies suffered from PTSD. A singular article delved into both PTSD and traumatic brain injury, whereas the remaining nine exclusively addressed PTSD. Each study specified age brackets, with participating veterans ranging from 25 to 69 years of age.

Table 3 shows the four equine intervention methodologies employed for the veterans. This table also elucidates the study design, assessment tools, veterans’ evaluation as research participants, post-intervention assessments, and the ensuing research outcomes.

TABLE 3

Table 3. Investigation of equine-assisted interventions for veterans.

All 10 articles are underpinned by experimentally derived data. Broadly speaking, each article’s primary objective is to evaluate the efficacy of equine intervention as a therapeutic approach for veterans diagnosed with PTSD. Seven articles reported treatments administered weekly; one detailed interventions conducted on consecutive days; and two articles did not specify the duration of treatment but underscored its completion within the experimental timeframe. Out of the 10 articles, two explicitly indicated that PTSD diagnostic tests were conducted during participant recruitment, while the remaining articles relied on medical records for participant screening.

Table 4 delineates the specific interventions employed in each study, describes the data measurement methodologies, and summarizes both the findings and the identified limitations of these studies.

TABLE 4

Table 4. Main findings.

All 10 articles presented four unique equine interventions: five studies focused on EAT, two on EAS, two on EAAT, and one on EAP. Four of these studies employed questionnaires assessing quality of life, whereas seven used questionnaires specific to the diagnosis of mental disorders. Six articles conclusively established the efficacy of the equine intervention in symptom mitigation, but two did not yield definitive results. Within these inconclusive studies, two suggested potential treatment benefits, while the other two observed a resurgence of symptoms in the subjects 3 months post-intervention.

In terms of limitations, four studies highlighted their limited sample sizes. Sylvia et al. articulated that, rather than a clinical trial, their study sought to ascertain the feasibility of employing EAAT for veterans undergoing PTSD and/or TBI treatment (48). Marchand et al., across two distinct studies, emphasized that their research was not controlled and thus could not definitively establish causation (33, 46). Romaniuk et al. acknowledged the absence of a control group in their experiments (50). Fisher et al.’s study lacked an actively treated control arm (52), while Johnson et al. pointed out that environmental factors and data collection methods potentially influenced their experimental results (53).

Table 5 presents a descriptive overview of explanation and summary of how the equine-assisted interventions were executed across various studies.

TABLE 5

Table 5. Explanation of horse intervention research.

Before initiating any experiment, participants were briefed about the treatment procedures and underwent preliminary exercises. Table 6 reveals that the average duration for the 10 EAT studies spanned 11 weeks, whereas EAAT treatments averaged a considerably shorter duration of 3.5 days. Every equine intervention approach necessitated more than 1 h per session.

TABLE 6

Table 6. Equine-assisted interventions details.

Three studies included a three-month follow-up evaluation, and another had a follow-up after just 6 days. As per Table 4, both Arnon et al. and Romaniuk et al. observed symptom recurrences and elevated test questionnaire scores after a three-month interval (23, 50, 52). Riding activities, with an emphasis on safety precautions, were featured in only four studies, three of which centered on EAT and one on EAS. Merely three out of the 10 studies ensured a compatibility match between the horses and the participants and also tended to the well-being of the involved horses. Two studies immersed participants in diverse activities, encompassing mounted exercises, horse tack routines, daily interactions, and family engagement. Six studies integrated specific therapeutic practices. Noteworthily, Malinowski et al. conducted simultaneous equine welfare assessments during their PTSD research, confirming that the treated horses remained unharmed (36).

4. Discussion

Preliminary data from the U.S. Army Medical Department suggest the potential benefits of animal-assisted therapy for wounded warriors participating in an occupational therapy life skills program. This underscores the significance of extended research in utilizing AAT as supplementary therapy for veterans diagnosed with PTSD and associated traumatic injuries (54).

The current review indicates that subjects showed discernible improvements in PTSD symptoms and a slight reduction in heart rate. Such findings align with established literature that details a multitude of potential physical and psychological advantages associated with animal-assisted interventions. In relation to EAAT studies that incorporated animals other than horses, the treatment duration was typically short-lived. A notable study elucidated that interacting or conversing with a dog led to reduced heart rates in participants. Within our reviewed research, the impact of EAAT involving horses on heart rate was especially prominent on days when veterans exhibited less activity and devoted more time to horse grooming and petting, as opposed to leading and roaming (55).

In studies utilizing EAAT with other animals apart from horses, treatment duration was typically brief. One study revealed that participants’ heart rates decreased when touching or conversing with a dog (56). The EAAT treatment with horses in the research we reviewed had an effect on heart rate, particularly on days when the veterans were more sedentary and spent more time grooming and petting the horses than leading and walking around (36).

Through a systems mapping analysis, we discerned that equine interventions could potentially benefit veterans with PTSD. A recurrent limitation in such studies, however, is the ambiguous details concerning the horses’ treatment within the research methodologies. While there are distinct breeds used for therapeutic purposes, the four horse-assisted therapies delineated in the summaries across these 10 articles exhibit no significant variation. Definitions across various categories also seem to converge.

Patients with PTSD face challenges in controlling emotions, maintaining reliance in relationships, and often harbor negative attitudes (57). Given these issues, the therapeutically value of equine-assisted interventions becomes evident, deriving from their attributes like fostering social relationships, sensory intentions, and their inherent inclusiveness and strength (58). Interacting with these huge animals provides patients both a sensory experience and a sense of control; this is further augmented by an experience-oriented approach that bolsters communication and mindful awareness during equine therapy (59). Through interaction with horses, patient benefit from emotional regulation and reflection (60). Apart from cognitive aspects, the experiential method of non-verbal embodiment combines physical and emotional dimensions, aiding emotional regulation, stress management, bolstering self-direction and resilience (61–63). Consequently, patients are better poised to re-establish trust. A review highlighted a statistically significant clinical improvement in symptoms after merely five 1-h sessions with horses (53). While traditional PTSD therapies can be prolonged, equine-assisted intervention therapy be a swift and effective method. Given that PTSD is a substantial predictor of suicidal ideation, the urgency for rapid-result treatments is essential.

Regarding equine welfare, horses engaged in therapeutic interventions encounter stressors, defined as environmental stimuli triggering homeostatic imbalances. Such stimuli elicit behavioral alterations, diminished immunity, and activations of the hypothalamic–pituitary–adrenal (HPA) axis alongside the autonomic nervous system (64). Chronic activation of any neuroendocrine axis can compromise equine welfare. The detrimental impact of a stressor hinges not on its intrinsic properties (intensity, duration, frequency) but on the predictability and controllability for the horse.

A specific horse study indicated that seasoned and rodeo-familiar horses manifest lower cortisol levels compared to their less experienced counterparts (65). The horses in our reviewed studies did not exhibit heightened fitness. Glucocorticoids have been prevalently employed as welfare indicators in animal welfare research (64). During EAAT sessions, horses exhibited reduced heart rates; metrics such as the standard deviation of normal-to-normal R-R intervals (SDNN) and the sympatho-vagal balance (LF/HF) ratio remained stable, implying a non-stressful session. Notably, in contrast to infrequent human-horse experimental setups, horses in Malinowski and colleagues’ EAAT investigations appeared unaltered (36).

EAT was adapted to address PTSD, with a variant being THR, categorized as an EAT sub-type. Fisher et al. posited that EAT-PTSD is safe and generally well-received (52). It could potentially engage avoidant patients averse to structured treatments, thereby fostering receptivity to further interventions. Johnson et al.’s findings highlight that the THR method involves direct riding, leveraging the necessity for riders to engage core muscles to remain upright on the horse (53). This enhances physical activity, diminishes stress, bolsters coping self-efficacy, and augments potential social support opportunities, potentially ameliorating PTSD symptoms and enriching veterans’ mental well-being.

Of the reviewed articles, only Burton et al. applied the EAP intervention approach. However, based on the intervention descriptions, participants were not involved in combined riding and psychotherapy sessions, rendering this EAP variant less impactful compared to others.

Extensive studies have underscored the efficacy of EAS in mitigating depression, anxiety, and PTSD symptoms among veterans (33, 66–69). Marchand et al., based in a prominent medical center, conceived the EAS-Whispers with Horses intervention in a bid for standardization. This method amalgamates mindfulness and self-compassion into a six-session psychotherapy and horse (PIH) program tailored for traumatized veterans. The integration with other psychotherapies, however, warrants further empirical validation.

5. Conclusion

In this systematic review, we critically evaluated publications from the last 5 years relevant to equine interventions for veterans with PTSD. Across the board, regardless of the specific equine intervention applied, all veterans with PTSD exhibited benefits.

While the majority of the examined studies utilized the EAT method, EAAT, although less frequently adopted, demonstrated pronounced effects even over short durations. Both EAS and EAP methods were comparatively rare, but their effectiveness was evident. A conspicuous gap in the literature is the detailed description of these interventions, underscoring the need for comprehensive investigation. Detailed delineation of intervention methodologies is imperative, as it can further optimize equine welfare within the interventions.

Of note, only a minority of the studies reviewed incorporated follow-up assessments, pivotal for discerning the longevity of the treatment effects on veterans with PTSD. Given that symptom recurrence is not uncommon post-treatment, there is a dearth of research on this front. Future inquiries should prioritize discerning whether the therapeutic effects persist over time.

Treating patients with PTSD often spans several years. However, all studies in the review indicate efficacy within a 6-month period. Equine-assisted intervention emphasize emotional regulation, mental control, and the mitigation of negative attitudes. Given these facets, other mental disorders share similar traits. Hence, there’s optimism that equine-assisted intervention therapy may benefit a wider range of patients in the future.

Furthermore, the methodologies lacked extensive descriptions regarding the horses’ roles in the interventions. This oversight is significant; a thorough understanding of the equine intervention methodology is essential to evaluate its impact on treatment outcomes more comprehensively.

Our review was confined to English-language studies, potentially omitting relevant research in other languages. Conventional systematic reviews typically do not include a rigorous assessment of the included studies, and in alignment, we did not undertake such an evaluation. Additionally, a granular evaluation of each individual equine intervention study was not conducted.

Author contributions

JL: Methodology, Resources, Validation, Writing – original draft. RS-G: Supervision, Validation, Writing – review & editing.

Funding

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

References

1. Berg, EL, and Causey, A. The life-changing power of the horse: equine-assisted activities and therapies in the U.S. Anim Front. (2014) 4:72–5. doi: 10.2527/af.2014-0025

CrossRef Full Text | Google Scholar

2. Masini, A. Equine-assisted psychotherapy in clinical practice. J Psychosoc Nurs Ment Health Serv. (2010) 48:30–4. doi: 10.3928/02793695-20100831-08

PubMed Abstract | CrossRef Full Text | Google Scholar

3. Eagala (2023). Eagala - a global standard in equine-assisted psychotherapy and personal development [internet]. Available at: https://www.eagala.org/programs;d=None (Accessed May 23, 2023).

Google Scholar

4. Lee, PT, Dakin, E, and McLure, M. Narrative synthesis of equine-assisted psychotherapy literature: current knowledge and future research directions. Health Soc Care Commun. (2016) 24:225–46. doi: 10.1111/hsc.12201

CrossRef Full Text | Google Scholar

5. Zinzow, HM, Grubaugh, AL, Frueh, BC, and Magruder, KM. Sexual assault, mental health, and service use among male and female veterans seen in veterans affairs primary care clinics: a multi-site study. Psychiatry Res. (2008) 159:226–36. doi: 10.1016/j.psychres.2007.04.008

PubMed Abstract | CrossRef Full Text | Google Scholar

6. Murdoch, M, Polusny, MA, Hodges, J, and O’Brien, N. Prevalence of in-service and post-service sexual assault among combat and noncombat veterans applying for Department of Veterans Affairs posttraumatic stress disorder disability benefits. Mil Med. (2004) 169:392–5. doi: 10.7205/MILMED.169.5.392

PubMed Abstract | CrossRef Full Text | Google Scholar

7. Hoge, CW, Castro, CA, Messer, SC, McGurk, D, Cotting, DI, and Koffman, RL. Combat duty in Iraq and Afghanistan, mental health problems, and barriers to care. N Engl J Med. (2004) 351:13–22. doi: 10.1056/NEJMoa040603

PubMed Abstract | CrossRef Full Text | Google Scholar

8. Palomar-Ciria, N, and Bello, HJ. Equine-assisted therapy in post-traumatic-stress disorder: a systematic review and Meta-analysis. J Equine Vet. (2023) 128:104871. doi: 10.1016/j.jevs.2023.104871

PubMed Abstract | CrossRef Full Text | Google Scholar

9. Marchand, WR. Potential mechanisms of action and outcomes of equine-assisted Services for Veterans with a history of trauma: a narrative review of the literature. IJERPH. (2023) 20:6377. doi: 10.3390/ijerph20146377

PubMed Abstract | CrossRef Full Text | Google Scholar

10. American Psychiatric Association (2023). Diagnostic and Statistical Manual of Mental Disorders [Internet]. Fifth Edition. American Psychiatric Association. 2013. Available at: https://psychiatryonline.org/doi/book/10.1176/appi.books.9780890425596 (Accessed May 26, 2023).

Google Scholar

11. Sareen, J, Cox, BJ, Afifi, TO, Stein, MB, Belik, SL, Meadows, G, et al. Combat and peacekeeping operations in relation to prevalence of mental disorders and perceived need for mental health care: findings from a large representative sample of military personnel. Arch Gen Psychiatry. (2007) 64:843–52. doi: 10.1001/archpsyc.64.7.843

PubMed Abstract | CrossRef Full Text | Google Scholar

12. Spitzer, C, Barnow, S, Völzke, H, John, U, Freyberger, HJ, and Grabe, HJ. Trauma, posttraumatic stress disorder, and physical illness: findings from the general population. Psychosom Med. (2009) 71:1012–7. doi: 10.1097/PSY.0b013e3181bc76b5

CrossRef Full Text | Google Scholar

13. Seng, JS, Graham-Bermann, SA, Clark, MK, McCarthy, AM, and Ronis, DL. Posttraumatic stress disorder and physical comorbidity among female children and adolescents: results from service-use data. Pediatrics. (2005) 116:e767–76. doi: 10.1542/peds.2005-0608

PubMed Abstract | CrossRef Full Text | Google Scholar

14. American Psychiatric Association, American Psychiatric Association. Diagnostic and statistical manual of mental disorders: DSM-5. 5th ed. Washington, D.C: American Psychiatric Association (2013). 947 p.

Google Scholar

15. Hourani, LL, Council CL, Hubal, RC, and Strange, LB. Approaches to the primary prevention of posttraumatic stress disorder in the military: a review of the stress control literature. Mil Med. (2011) 176:721–30. doi: 10.7205/MILMED-D-09-00227

PubMed Abstract | CrossRef Full Text | Google Scholar

16. Gillies, D, Taylor, F, Gray, C, O’Brien, L, and D’Abrew, N. Psychological therapies for the treatment of post-traumatic stress disorder in children and adolescents (review). Evid Based Child Health. (2013) 8:1004–116. doi: 10.1002/ebch.1916

CrossRef Full Text | Google Scholar

17. Bradley, R, Greene, J, Russ, E, Dutra, L, and Westen, D. A multidimensional meta-analysis of psychotherapy for PTSD. Am J Psychiatry. (2005) 162:214–27. doi: 10.1176/appi.ajp.162.2.214

PubMed Abstract | CrossRef Full Text | Google Scholar

18. Schneier, FR, Neria, Y, Pavlicova, M, Hembree, E, Suh, EJ, Amsel, L, et al. Combined prolonged exposure therapy and paroxetine for PTSD related to the world trade center attack: a randomized controlled trial. Am J Psychiatry. (2012) 169:80–8. doi: 10.1176/appi.ajp.2011.11020321

PubMed Abstract | CrossRef Full Text | Google Scholar

19. Engelman, SR. Palliative care and use of animal-assisted therapy. Omega. (2013) 67:63–7. doi: 10.2190/OM.67.1-2.g

PubMed Abstract | CrossRef Full Text | Google Scholar

20. Beck, AM. The use of animals to benefit humans. In: Handbook on animal-assisted therapy. (2006). 21–40. doi: 10.1016/b978-012369484-3/50004-9

CrossRef Full Text | Google Scholar

21. Jorgenson, J. Therapeutic use of companion animals in health care. Image J Nurs Sch. (1997) 29:249–54. doi: 10.1111/j.1547-5069.1997.tb00993.x

PubMed Abstract | CrossRef Full Text | Google Scholar

22. Farmer, SM. Integrating animal-assisted interventions in United States veterans with self-reported posttraumatic stress disorder. J Nurse Pract. (2021) 17:619–22. doi: 10.1016/j.nurpra.2021.02.001

CrossRef Full Text | Google Scholar

23. Kinney, AR, Eakman, AM, Lassell, R, and Wood, W. Equine-assisted interventions for veterans with service-related health conditions: a systematic mapping review. Mil Med Res. (2019) 6:28. doi: 10.1186/s40779-019-0217-6

PubMed Abstract | CrossRef Full Text | Google Scholar

24. McCardle, P, McCune, S, Griffin, JA, and Maholmes, V. How animals affect us: examining the influences of human–animal interaction on child development and human health, vol. xvi. Washington, DC, US: American Psychological Association (2011). 228 p.

Google Scholar

25. Nurenberg, JR, Schleifer, SJ, Shaffer, TM, Yellin, M, Desai, PJ, Amin, R, et al. Animal-assisted therapy with chronic psychiatric inpatients: equine-assisted psychotherapy and aggressive behavior. Psychiatr Serv. (2015) 66:80–6. doi: 10.1176/appi.ps.201300524

PubMed Abstract | CrossRef Full Text | Google Scholar

26. Ahn, B, Joung, YS, Kwon, JY, Lee, DI, Oh, S, Kim, BU, et al. Effects of equine-assisted activities on attention and quality of life in children with cerebral palsy in a randomized trial: examining the comorbidity with attention-deficit/hyperactivity disorder. BMC Pediatr. (2021) 21:135. doi: 10.1186/s12887-021-02597-0

PubMed Abstract | CrossRef Full Text | Google Scholar

27. Alfonso, SV, Alfonso, LA, Llabre, MM, and Fernandez, MI. Project stride: an equine-assisted intervention to reduce symptoms of social anxiety in young women. Explore. (2015) 11:461–7. doi: 10.1016/j.explore.2015.08.003

PubMed Abstract | CrossRef Full Text | Google Scholar

28. Bass, MM, Duchowny, CA, and Llabre, MM. The effect of therapeutic horseback riding on social functioning in children with autism. J Autism Dev Disord. (2009) 39:1261–7. doi: 10.1007/s10803-009-0734-3

CrossRef Full Text | Google Scholar

29. Chinniah, H, Natarajan, M, Ramanathan, R, and Ambrose, JWF. Effects of horse riding simulator on sitting motor function in children with spastic cerebral palsy. Physiother Res Int. (2020) 25:e1870. doi: 10.1002/pri.1870

PubMed Abstract | CrossRef Full Text | Google Scholar

30. Matusiak-Wieczorek, E, Dziankowska-Zaborszczyk, E, Synder, M, and Borowski, A. The influence of Hippotherapy on the body posture in a sitting position among children with cerebral palsy. Int J Environ Res Public Health. (2020) 17:6846. doi: 10.3390/ijerph17186846

PubMed Abstract | CrossRef Full Text | Google Scholar

31. Park, S, Park, S, Yoo, J, and Jee, YS. Effects of equine riding on static and dynamic mechanical contraction of the thighs and trunk muscles in inactive women. J Back Musculoskelet Rehabil. (2021) 34:521–35. doi: 10.3233/BMR-200008

PubMed Abstract | CrossRef Full Text | Google Scholar

32. Bachi, K, Terkel, J, and Teichman, M. Equine-facilitated psychotherapy for at-risk adolescents: the influence on self-image, self-control and trust. Clin Child Psychol Psychiatry. (2012) 17:298–312. doi: 10.1177/1359104511404177

PubMed Abstract | CrossRef Full Text | Google Scholar

33. Marchand, WR, Andersen, SJ, Smith, JE, Hoopes, KH, and Carlson, JK. Equine-assisted activities and therapies for veterans with posttraumatic stress disorder: current state, challenges and future directions. Chronic Stress. (2021) 5:2470547021991556. doi: 10.1177/2470547021991556

CrossRef Full Text | Google Scholar

34. Burton, LE, Qeadan, F, and Burge, MR. Efficacy of equine-assisted psychotherapy in veterans with posttraumatic stress disorder. J Integrat Med. (2019) 17:14–9. doi: 10.1016/j.joim.2018.11.001

PubMed Abstract | CrossRef Full Text | Google Scholar

35. Ferruolo, DM. Psychosocial equine program for veterans. Soc Work. (2016) 61:53–60. doi: 10.1093/sw/swv054

PubMed Abstract | CrossRef Full Text | Google Scholar

36. Malinowski, K, Yee, C, Tevlin, JM, Birks, EK, Durando, MM, Pournajafi-Nazarloo, H, et al. The effects of equine assisted therapy on plasma cortisol and oxytocin concentrations and heart rate variability in horses and measures of symptoms of post-traumatic stress disorder in veterans. J Equine Vet. (2018) 64:17–26. doi: 10.1016/j.jevs.2018.01.011

PubMed Abstract | CrossRef Full Text | Google Scholar

37. Yoo, JH, Kim, SE, Lee, MG, Jin, JJ, Hong, J, Choi, YT, et al. The effect of horse simulator riding on visual analogue scale, body composition and trunk strength in the patients with chronic low back pain. Int J Clin Pract. (2014) 68:941–9. doi: 10.1111/ijcp.12414

PubMed Abstract | CrossRef Full Text | Google Scholar

38. Aranda-García, S, Iricibar, A, Planas, A, Prat-Subiran, JA, and Angulo-Barroso, RM. Comparative effects of horse exercise versus traditional exercise programs on gait, muscle strength, and body balance in healthy older adults. J Aging Phys Act. (2015) 23:78–89. doi: 10.1123/JAPA.2012-0326

PubMed Abstract | CrossRef Full Text | Google Scholar

39. Bunketorp-Käll, L, Lundgren-Nilsson, Å, Samuelsson, H, Pekny, T, Blomvé, K, Pekna, M, et al. Long-term improvements after multimodal rehabilitation in late phase after stroke: a randomized controlled trial. Stroke. (2017) 48:1916–24. doi: 10.1161/STROKEAHA.116.016433

PubMed Abstract | CrossRef Full Text | Google Scholar

40. Žalienė, L, Mockevičienė, D, Kreivinienė, B, Razbadauskas, A, Kleiva, Ž, and Kirkutis, A. Short-term and long-term effects of riding for children with cerebral palsy gross motor functions. Biomed Res Int. (2018) 2018:1–6. doi: 10.1155/2018/4190249

PubMed Abstract | CrossRef Full Text | Google Scholar

41. Hemachithra, C, Meena, N, Ramanathan, R, and Felix, AJW. Immediate effect of horse riding simulator on adductor spasticity in children with cerebral palsy: a randomized controlled trial. Physiother Res Int. (2020) 25:e1809. doi: 10.1002/pri.1809

PubMed Abstract | CrossRef Full Text | Google Scholar

42. Uchiyama, H, Ohtani, N, and Ohta, M. Three-dimensional analysis of horse and human gaits in therapeutic riding. Appl Anim Behav Sci. (2011) 135:271–6. doi: 10.1016/j.applanim.2011.10.024

CrossRef Full Text | Google Scholar

43. Silkwood-Sherer, D. The difference lies in the perspective. NARHA’s Stride. (2003) 9:14–6.

Google Scholar

44. Yorke, J. (2003). The therapeutic value of the equine-human relationship in recovery from trauma: A qualitative analysis. Theses and dissertations (comprehensive) [internet]. Available at: https://scholars.wlu.ca/etd/168 (Accessed June 7, 2023).

Google Scholar

45. Wood, W, Alm, K, Benjamin, J, Thomas, L, Anderson, D, Pohl, L, et al. Optimal terminology for Services in the United States that Incorporate Horses to benefit people: a consensus document. J Altern Complement Med. (2021) 27:88–95. doi: 10.1089/acm.2020.0415

PubMed Abstract | CrossRef Full Text | Google Scholar

46. Marchand, WR, Lackner, R, Hartquist, A, Finnell, L, and Nazarenko, E. Evaluation of a mindfulness and self-compassion-based psychotherapy incorporating horses for veterans who have experienced trauma. Complement Ther Med. (2023) 72:102914. doi: 10.1016/j.ctim.2023.102914

PubMed Abstract | CrossRef Full Text | Google Scholar

47. Shelef, A, Brafman, D, Rosing, T, Weizman, A, Stryjer, R, and Barak, Y. Equine assisted therapy for patients with post traumatic stress disorder: a case series study. Mil Med. (2019) 184:394–9. doi: 10.1093/milmed/usz036

PubMed Abstract | CrossRef Full Text | Google Scholar

48. Sylvia, L, West, E, Blackburn, AM, Gupta, C, Bui, E, Mahoney, T, et al. Acceptability of an adjunct equine-assisted activities and therapies program for veterans with posttraumatic stress disorder and/or traumatic brain injury. J Integrat Med. (2020) 18:169–73. doi: 10.1016/j.joim.2020.01.005

CrossRef Full Text | Google Scholar

49. Marchand, WR, Smith, J, Hoopes, KH, Osborne, M, Andersen, SJ, Bell, K, et al. A pilot observational study of horsemanship skills training for veterans with posttraumatic stress disorder. Complement Ther Med. (2023) 72:102910. doi: 10.1016/j.ctim.2022.102910

PubMed Abstract | CrossRef Full Text | Google Scholar

50. Romaniuk, M, Evans, J, and Kidd, C. Evaluation of an equine-assisted therapy program for veterans who identify as ‘wounded, injured or ill’ and their partners. PLoS One. (2018) 13:e0203943. doi: 10.1371/journal.pone.0203943

PubMed Abstract | CrossRef Full Text | Google Scholar

51. Arnon, S, Fisher, PW, Pickover, A, Lowell, A, Turner, JB, Hilburn, A, et al. Equine-assisted therapy for veterans with PTSD: manual development and preliminary findings. Mil Med. (2020) 185:e557–64. doi: 10.1093/milmed/usz444

PubMed Abstract | CrossRef Full Text | Google Scholar

52. Fisher, PW, Lazarov, A, Lowell, A, Arnon, S, Turner, JB, Bergman, M, et al. Equine-assisted therapy for posttraumatic stress disorder among military veterans: an open trial. J Clin Psychiatry. (2021) 82:21m14005. doi: 10.4088/JCP.21m14005

PubMed Abstract | CrossRef Full Text | Google Scholar

53. Johnson, RA, Albright, DL, Marzolf, JR, Bibbo, JL, Yaglom, HD, Crowder, SM, et al. Experiences of military veterans in a therapeutic horseback riding program. Clin Nurs Res. (2021) 30:38–45. doi: 10.1177/10547738211003580

PubMed Abstract | CrossRef Full Text | Google Scholar

54. Gonzales, F, Jr, S, Haertlein, C, Jones, C, and Reer, T. The effects of animal-assisted therapy on wounded warriors in an occupational therapy life skills program. US Army Med Dep J. (2012):1524–0426.

Google Scholar

55. Beetz, A, Uvnäs-Moberg, K, Julius, H, and Kotrschal, K. Psychosocial and psychophysiological effects of human-animal interactions: the possible role of oxytocin. Front Psychol. (2023) 3:234. doi: 10.3389/fpsyg.2012.00234

PubMed Abstract | CrossRef Full Text | Google Scholar

56. Vormbrock, JK, and Grossberg, JM. Cardiovascular effects of human-pet dog interactions. J Behav Med. (1988) 11:509–17. doi: 10.1007/BF00844843

PubMed Abstract | CrossRef Full Text | Google Scholar

57. Maercker, A, Brewin, CR, Bryant, RA, Cloitre, M, Reed, GM, van Ommeren, M, et al. Proposals for mental disorders specifically associated with stress in the international classification of diseases-11. Lancet. (2013) 381:1683–5. doi: 10.1016/S0140-6736(12)62191-6

PubMed Abstract | CrossRef Full Text | Google Scholar

58. Kovács, G. Experiential equine-assisted focal psychodynamic psychotherapy: addressing personality and attachment in clients with chronic childhood trauma. In: Equine-assisted mental health for healing trauma. Ed. Trotter KS. New York: Routledge (2018). 107–22.

Google Scholar

59. Anestis, MD, Anestis, JC, Zawilinski, LL, Hopkins, TA, and Lilienfeld, SO. Equine-related treatments for mental disorders lack empirical support: a systematic review of empirical investigations. J Clin Psychol. (2014) 70:1115–32. doi: 10.1002/jclp.22113

PubMed Abstract | CrossRef Full Text | Google Scholar

60. Selby, A, and Smith-Osborne, A. A systematic review of effectiveness of complementary and adjunct therapies and interventions involving equines. Health Psychol. (2013) 32:418–32. doi: 10.1037/a0029188

PubMed Abstract | CrossRef Full Text | Google Scholar

61. Porges, SW. The polyvagal theory: phylogenetic substrates of a social nervous system. Int J Psychophysiol. (2001) 42:123–46. doi: 10.1016/S0167-8760(01)00162-3

PubMed Abstract | CrossRef Full Text | Google Scholar

62. Van der Kolk, B. (2014). The body keeps the score: brain, mind, and body in the healing of trauma. New York. 3.

Google Scholar

63. Perry, BD. (2006). Applying principles of neurodevelopment to clinical work with maltreated and traumatized children: The neurosequential model of therapeutics.

Google Scholar

64. Moberg, GP. Biological response to stress: implications for animal welfare In: GP Moberg and JA Mench, editors. The biology of animal stress: Basic principles and implications for animal welfare [internet]. 1st ed. UK: CABI Publishing (2000). 1–21.

Google Scholar

65. Covalesky, ME, Russoniello, CR, and Malinowski, K. Effects of show-jumping performance stress on plasma cortisol and lactate concentrations and heart rate and behavior in horses. J Equine Vet. (1992) 12:244–51. doi: 10.1016/S0737-0806(06)81454-1

CrossRef Full Text | Google Scholar

66. Lanning, BA, and Krenek, N. Guest editorial: examining effects of equine-assisted activities to help combat veterans improve quality of life. J Rehabil Res Dev. (2013) 50:vii–xiii. doi: 10.1682/JRRD.2013.07.0159

PubMed Abstract | CrossRef Full Text | Google Scholar

67. Wharton, T, Whitworth, J, Macauley, E, and Malone, M. Pilot testing a manualized equine-facilitated cognitive processing therapy (EF-CPT) intervention for PTSD in veterans. Psychiatr Rehabil J. (2019) 42:268–76. doi: 10.1037/prj0000359

PubMed Abstract | CrossRef Full Text | Google Scholar

68. Goodson, J, Helstrom, A, Halpern, JM, Ferenschak, MP, Gillihan, SJ, and Powers, MB. Treatment of posttraumatic stress disorder in U.S. combat veterans: a meta-analytic review. Psychol Rep. (2011) 109:573–99. doi: 10.2466/02.09.15.16.PR0.109.5.573-599

PubMed Abstract | CrossRef Full Text | Google Scholar

69. Steele, E, Wood, DS, and Usadi, J E, Applegarth, DM. TRR’s warrior camp: an intensive treatment program for combat trauma in active military and veterans of all eras. Mil Med (2018). 183:403–407, doi: 10.1093/milmed/usx153

PubMed Abstract | CrossRef Full Text | Google Scholar