Table 1.

Characteristics of the included studies

Study	Study origin	Type of study	n/ M:F (%)	Mean age (yrs)	Type of EAS	Summary of EAT programme	Duration and Frequency	PTSD outcome measure
Johnson et al. 2018 [19]	USA	RCT	38/ 84:16	54	THR	THR classes held at a Professional Association of Therapeutic Horsemanship accredited riding centre. Staff focused on horsemanship, tacking up, safety and grooming	One 50–60 min session per week for 6 weeks	PCL-M
Fisher et al. 2021 [20]	USA	Clinical Open Trial	63/ 63:37	50	PIH	Session co-led by licensed mental health professional and qualified equine specialist. Mental health professional to facilitate reflection, observation and direction. Psychoeducation, interaction with horses in the round pen. Grounding exercises, grooming, leading horses, team work exercises with the horse in different situations, followed by team feedback and closing circle for discussions All sessions were videotaped by researchers	One 90 min session per week for 8 weeks	PCL-5 CAPS-5
Arnon et al. 2020 [21]	USA	Clinical Open Trial	8/ 75:25	45	PIH	Session co-led by mental health professional and equine specialist. Sessions included grounding exercise, relaxation exercises, ‘join up’ activity, team work exercises and reflection opportunities	One 90 min session per week for 8 weeks	PCL-5 CAPS-5
Zhu et al. 2020 [22]	USA	Clinical Open Trial	19/ 47:53	46	PIH	Grounding exercise, teaching on EAS rationale, psychoeducation, round pen meeting with horses. Team feedback and direction	One 90 min session per week for 8 weeks	PCL-5 (no numbers presented)
Romaniuk et al. 2018 [23]	Australia	Evaluation Study	36/ 81:19	46	PIH	Session co-led by Equine Psychotherapy Institute (Australia) Program Model of Equine Assisted Learning/Psychotherapy and a registered Psychologist. Sessions involved groundwork techniques and elements of natural horsemanship, learning new skills to create social engagement. Therapeutic work to explore issues, challenges, behaviours and build awareness of responses. Opportunities to reflect. Trail walks, mindfulness and group discussions	Five day residential programme	PCL-5
Burton et al. 2019 [24]	USA	Clinical Open Trial	20/ 80:20	47	PIH	Sessions co-led by Equine Assisted Growth and Learning Association (USA) and licensed occupational therapist. Sessions included ground based exercises using horses at metaphors, leading and obstacle exercises. Pre-session discussions with an occupational therapist. Targeted psychotherapy activity, goal setting and focus on positive lifestyle choices to manage PTSD symptoms. Post-activity discussions	One session per week for 6 weeks	PCL-M
Rosing et al. 2022 [25]	Israel	Evaluation Study	12/ Not stated	41	PIH and EAL	Providers of the programme not stated. PIH and EAL (equine-assisted learning) which had elements of teaching skills; grooming and tacking up, riding activities, vaulting, mounted basketball and more. Groundwork included sharing stories and beliefs and interpretation of self through tasks with the horses. Ending with group conversation to share experiences	One 3 h session per week over a 6 month period	Qualitative measures used
Sylvia et al. 2020 [26]	USA	Evaluation Study	62/ 83:17	37	PIH and EAL	Certified team of providers including licensed clinicians, a therapeutic riding instructor and equine specialist in mental health learning. PIH along with mindfulness- based activities. Therapeutic riding, driving, EAL, groundwork, horse-human energy, herd observation and equine care	2 week intensive programme, with an EAT weekend. 3 × 2 h long sessions	PCL-5
Johnson et al. 2021 [27]	USA	RCT	20/ 90:10	52	THR	Sessions provided by a certified riding instructor and a licensed occupational therapist. Grooming, riding, exercises built upon over the six weeks	One session per week for 6 weeks	Qualitative measures used
Ferruolo 2016 [28]	USA	Pilot Programme	8/ 100:0	Not stated	PIH	Sessions provided by clinical social work graduate and 2 equine-facilitated mental health experts at an established therapeutic horse farm. Sessions consisted of 70 min of psychoeducation, 285 min of guided experimental equine activities, 315 min of group processing and personal reflection	Two day intensive option	Qualitative measures used
Malinowski et al. 2018 [29]	USA	Original Research	7/ 86:14	58	PIH	Sessions were led by a team including a licensed psychologist and a PATH licensed therapeutic riding instructor and equine specialist in mental health and learning. EAS and PIH sessions included horsemanship, obstacle course and mindfulness, horse chalking and active feeling exercises and grounding exercises mixed with association between positive feelings	5 × 1 h EAT sessions over 5 consecutive days	PCL-5
Marchland et al. 2023 [30]	USA	Observational Study	18/ Not stated	46	THR	Session adhered to PATH safety standards in a university equine facility. Intervention included two sessions of horsemanship and two sessions of trail rides lasting 45 min each. Session one and two focused on learning basic equine ground skills and mounting. Sessions three and four consisted of ride preparation, riding and debriefs	One session per week over 4 weeks. First two sessions 4 h in length, final two lasted 2 h	PCL-V
Marchland et al. 2023 [31]	USA	Evaluation Study	33/ 51.5:48.5	46	PIH	Sessions were provided by a licensed mental health clinician and an equine specialist. Activities focused on mindfulness, grooming, equine behaviour and communication, leading, group discussions (self-compassion, psychological safety, psychological resilience, ‘how would I treat a friend’, approaches to difficult and emotions and a guilt and shame discussion) and meditation	One session per week for 6 weeks lasting 90 min	PCL-V

CAPS-5 clinician administered PCL, EAL equine-assisted learning, EAS equine-assisted Services, PCL-5 post-traumatic stress disorder checklist (standard), PCL-V post-traumatic stress disorder checklist (Veteran), PCL-M post-traumatic stress disorder checklist (Military), PTSD posttraumatic stress disorder, RCT randomised controlled trial, THR therapeutic horseback riding, N number of participants, M:F male: female ratio, PATH Professional Association of Therapeutic Horsemanship (USA), PIH psychotherapy involving horses