Table 3.
Characteristics and results of the 28 studies with pre-post and pre-follow-up effect sizes of AAI regarding PTSD symptom and/or depression severity
| First author, Publication year | Study design | N analysed | Gender | Age (range, M, SD) |
Type of experienced trauma | Participating animals | Treatment provider | AAI terminology | Pre-post SMC (95% CI) at end of treatmenta | Pre-follow-up SMD (95% CI) at end of treatmenta |
|---|---|---|---|---|---|---|---|---|---|---|
| Bergen-Cico (2018) | Control | 34 | NR | M = 42, SD = 11.5 | War | Dogs | Dog trainer | Therapeutic dog ownership and training | PTSD: −0.43 (−0.66 to −0.21) | NA |
| Burton (2019) | Control | 11 | 16m/4fc | 33–63M = 47, SD = 14 | War | Horses | Occupational therapist, EAGALA-certified with professional horse handler | Equine-assisted psychotherapy | PTSD: −1.03 (−1.60 to −0.46) | NA |
| Craven (2013) | Pre-post | 5 | 4m/2fc | 26–66, M = 44, SD = 15.4 | War, sexual abuse | Horses | Clinical psychologist/equine specialist, counsellor, equine specialist | Equine-assisted psychotherapy | PTSD: −4.28 (−6.98 to −1.58) | NA |
| Dietz (2012) | Control | 121 | 10m/143fc | 7–17 | Sexual abuse | Dogs | Licenced and master’s level clinicians (social work, trained psychologists, counselling) | Animal-assisted therapy | PTSD: −0.59 (−0.71 to −0.46) | NA |
| Earles (2015) | Pre-post | 16 | 4m/12f | 33–62, M = 51.25, SD = 9.99 | Various traumas | Horses | NR | Equine-assisted therapy | PTSD: −0.78 (−1.17 to −0.39) Depression: −0.33 (−0.63 to −0.03) |
NA |
| Faye (2003) | Pre-post | 3 | 6m/7fc | 7–11, M = 9.18, SD = 1.40 | Nature | Dolphins | Psychologist | Dolphin interaction | PTSD: −0.94 (−1.94 to 0.05) | NA |
| Gómez (2016) | Pre-post | 5 | 6m/2fc | 46–76, M = 58, SD = 9.85 | War | Horses | Certified PATH International therapeutic riding instructor and certified therapeutic recreation specialist | Equine therapy | PTSD: −0.44 (−1.00 to 0.13) | PTSD: -0.58 (−1.31 to 0.15) |
| Hamama (2011) | Pre-postb | 9 | 0m/9f | 14–16,M = 14.9, SD = 1.5 | Physical or sexual abuse | Dogs | Social work students and professional animal-assisted therapist | Dog-assisted therapy | PTSD: −0.69 (−1.18 to −0.20) Depression: −0.47 (−0.89 to −0.04) |
NA |
| Johnson (2018) | RCT | 19 | 32m/6fc | 29–73, M = 54.35, SD = 12.85 | War | Horses | Occupational therapists and PATH-certified riding instructors | Therapeutic horseback riding | PTSD: −0.73 (−1.07 to −0.39) | NA |
| Kemp (2014) | Pre-post | 30 | 6m/24f | Children: 8–11, M = 9.8, SD = 1.3 Adolescents: 12–17, M = 15.5, SD = 0.8 |
Physical or sexual abuse, neglect | Horses | Counsellors | Equine-facilitated therapy | PTSD: −3.73 (−4.70 to −2.76) Depression: −1.31 (−1.70 to −0.92) |
NA |
| Kloep (2017) | Pre-post | 12 | 9m/4fc | Cohort 1: 26–70, M = 44, SD = 15.4 Cohort 2:23–53, M = 36, SD = 13 |
War | Dogs | NR | Animal-assisted therapy | PTSD: −4.31 (−6.06 to −2.56) Depression: −2.76 (−3.91 to −1.61) |
PTSD: −3.92 (−5.67 to −2.17) |
| Lanning (2013) | Pre-post | 7 | 10m/3fc | 29–52, M = 35.5, SD = 6.9 | War | Horses | Veteran volunteers | Equine-assisted activities | Depression: −0.50 (−0.99 to −0.00) | NA |
| Lanning (2017) | Pre-post | 39 | 33m/18fc | 22–57, M = 36.8, SD = 11.26 | War | Horses | Volunteers | Therapeutic horseback riding | PTSD: −0.79 (−1.07 to −0.51) | PTSD: −0.52 (−0.81 to −0.22) |
| Malinowski (2018) | Pre-post | 7 | 6m/1f | 31–68, M = 58, SD = 13.14 | War | Horses | Licenced therapist and certified equine specialist | Equine-assisted activities and therapies | PTSD: −1.16 (−1.90 to −0.42) | NA |
| McCullough (2011)/McCullough (2015) | Pre-post | 11 | 6m/5f | 10–18, M = 13.73 SD = 2.83 | Physical, sexual, emotional abuse and neglect | Horses | Psychotherapist | Equine-facilitated psychotherapy | PTSD: −0.47 (−0.86 to −0.08) | NA |
| Mueller (2017) | Control | 25 | 45m/9fc | 10–18 | Physical, sexual, emotional abuse and neglect | Horses | Licenced clinical social worker | Equine-facilitated psychotherapy | PTSD: −0.38 (−0.63 to −0.14) | NA |
| Naste (2018) | Pre-post | 2 | 0m/3f | 10–12, M = 11, SD = 1 | Sexual abuse, neglect | Horses | Registered mental health practitioner | Equine-facilitated therapy | PTSD: 0.54 (−0.40 to 1.49) | NA |
| O’Haire (2018) | Control | 75 | 110m/31fc | M = 37.1, SD = 8.3 | War | Dogs | NA | Service dog | PTSD: −1.00 (−1.21 to −0.80) | NA |
| Romaniuk (2018) | Pre-post | 42 | 30m/17fc | 26–72, M = 46.46, SD = 12, 46 | War | Horses | EEA facilitators, certified in the Equine Psychotherapy Institute, accompanied by a psychologist | Equine-assisted therapy | PTSD: Couples: −0.61 (−0.91 to −0.32) Individual: −0.79 (−1.14 to −0.44) Depression: Couples −1.04 (−1.42 to −0.65) Individual −1.18 (−1.57 to −0.78) |
PTSD: Couples −0.85 (−1.20 to −0.50) Individual 0.23 (−0.21 to 0.69) Depression: Couples −0.78 (−1.23 to −0.32) Individual 0.30 (−0.27 to 0.87) |
| Schramm (2015) | Pre-post | 6 | NR | 21–64, M = 47.67, SD = 16.06 | Not specified | Sheep | Psychotherapist | Animal-assisted mindfulness training | Depression: −0.10 (−1.72 to −0.27) | NA |
| Shambo (2010) | Pre-post | 6 | 0m/6f | NR (older than 18) | Interpersonal violence | Horses | NR | Equine-facilitated psychotherapy | Depression: −2.94 (−4.66 to −1.22) | PTSD: −3.22 (−4.94 to −1.50) |
| Sheade (2015) | Pre-post | 3 | 3m/1fc | 32–67 | War | Horses | Principal investigator, Licenced Professional Counsellor (LPC) also PATH certified equine specialist | Relational equine-partnered counselling | PTSD: – 1.64 (−3.11 to −0.18) | NA |
| Signal (2013) | Pre-post | 44 | 6m/38f | Children: 8–11, M = 9.8, SD = 1.3 Adolescents: 12–17, M = 15.5, SD = 0.8 Adults: 19–50, M = 37 |
Sexual abuse | Horses | EAGALA counsellors | Equine-facilitated therapy | Depression: Children: −1.82 (−2.53 to −1.11) Youth: −1.31 (−1.85 to −0.76) Adult: −2.19 (−3.05 to −1.33) |
NA |
| Signal (2017) | Pre-post | 20 | 12m/8f | 5–12, M = 8.0, SD = 2.0 | Sexual abuse | Dogs | Dog handler/owner and specialized RSPCA education officer in conjunction with PH staff | Animal-assisted therapy | PTSD: −0.87 (−1.23 to −0.50) | NA |
| Steele (2018) | Pre-post | 85 | 60m/25f | 22–72, M = 42.94, SD = 11.63 | War | Horses | Mental health professional and equine professional | Equine-assisted psychotherapy | PTSD: −0.70 (−0.86 to −0.54) Depression: −0.84 (−1.01 to −0.67) |
NA |
| Vincent (2017) | Pre-post | 15 | 15m/5fc | 31–61+ | War | Dogs | Dog trainers/NA | Service dog | PTSD: −1.10 (−1.59 to −0.61) Depression: −0.74 (−1.13 to −0.35) |
NA |
| Whittlesey-Jerome (2014) | Control | 6 | 0m/13f | 28–64, M = 43.75 | In abusive relationship | Horses | Mental health professional (licenced professional counsellor), or LPC credentialed by EAGALA | Equine-assisted psychotherapy | Depression: −0.37 (−0.84 to −0.09) | NA |
| Woolley (2004) | Control | 11 | 11m/10fc | 11–17 | Abuse, maltreatment | Farm animals | Staff person or volunteer | Animal-assisted therapy | Depression: 0.01 (−0.33 to 0.34) | NA |
N: number of analysed participants in the AAI group; M: mean; SD: standard deviation; SMD: standard mean change, CI: confidence interval; NR: not reported; NA: not applicable; AAI: animal-assisted intervention; anegative values indicate symptom improvement from beginning to end of treatment; bmatching group with no symptoms is not considered as control group, csome studies report gender only for included participants and not for the number of analysed participants.