Table 4.
Characteristics and results of the 13 studies included only in the narrative review
| First author, Publication year | Study design | N analysed (AAI/control) | Gender | Age (range, M, SD) |
Type of experienced trauma | Participating animals | Treatment provider | AAI terminology | Results |
|---|---|---|---|---|---|---|---|---|---|
| Balluerka (2014)a | Control | 46 (21/25) | 32m/14f | 12–17, M = 15.41, SD = 1.65 | Not specified | Dogs, horses, farm animals | Psychologist, specialized in AAT | Animal-assisted psychotherapy | Higher attachment security* after AAI compared to before treatment but no effect on other attachment dimensions; no difference between AAI and control group |
| Balluerka (2015)a | Control | 63 (39/24) | 42m/25fe | 12–17, M = 15.27, SD = 1.63 | Not specified | Dogs, horses, farm animals | Psychologist, specialized in AAT | Animal-assisted psychotherapy | No difference in clinical symptoms between AAI and control; subscale adaptive skills rated by teachers higher* in AAI compared to control but no difference in other subscales |
| Beck (2012) | Control | 24 (12/12) | 17m/7f | AAT: M = 37.08, SD = 11.79 CG: M = 35.5, SD = 9.19 |
War | Dogs | Dog handler | Animal-assisted therapy | No differences in mood, perceived stress, fatigue, functioning, and participation in everyday activities from pre- to post-assessment but decreased psychological function*, higher work performance* and higher quality of interaction*, no differences between AAI and control group. |
| Gehrke (2018) | Pre-post | 17 | NR | NR | War | Horses | Wranglers and counsellors | Equine therapy | Decreased low frequency/high frequency (LF/HF) ratio* in heart rate variability; Improvement in affect* (increase in self-esteem, reduction in irritability and anxiety) |
| Krause-Parello (2014)b | RCT | 42 (19/23) | 2m/40f | 5–14, M = 8.91, SD = 2.33 | Sexual abuse | Dogs | Therapist, dog and its handler | Animal-assisted intervention | Interaction effect* of dog and interview length on alpha amylase; trend of reduced immunoglobulin A with dog; interaction effect* of dog, age of child and interview length on heart rate |
| Krause-Parello (2015)b | RCT | 42 (19/23) | 2m/40f | 5–14, M = 8.91, SD = 2.33 | Sexual abuse | Dogs | Therapist, dog and its handler | Animal-assisted intervention | No differences regarding diastolic and systolic blood pressure and heart rate values for both the intervention and control groups; lower cortisol levels after intervention for control group* but not for AAI; no differences in immunoglobulin A before and after intervention or between AAI and control |
| Krause-Parello (2018) | Control | 25 (25/25) | 21m/4f | 33–86, M = 65.32, SD = 12.26 | War | Dog | Psychologist | Animal-assisted intervention | Therapy dog and psychologist both reduce cortisol and heart rate *; no effect on blood pressure, alpha amylase and immunoglobulin A between before and after control or treatment |
| Kruger (2012) | Pre-post | 15 | 11m/4f | 7–17, M = 11.13, SD = 3.11 | Not specified | Horses | Licenced mental health professionals | Trauma-focused equine-assisted psychotherapy | Decrease in functional impairment* (increase in subscales school behaviour*, home behaviour*, behaviour towards others*, community behaviour* and moods/emotions*; no change in subscales self-harmful behaviour scale and the problem thinking) |
| Miller (2018) | Pre-post | 31 | 31m/0f | 25–66, M = 41.23, SD = 11.86 | Not specified | Dogs | NA | Service animal | Canine presence was not a predictor of reports of nightmares and disturbed dreaming; elevated respiratory event index and lower prior-night sleep respiratory sinus arrhythmia predicted nightmares and disturbed dreams. |
| Murrow (2013) | Pre-post | 9 | 3m/6f | 4–12 | Physical or sexual abuse, domestic violence | Dogs | Therapist (not specified) and researcher (dog handler) | Animal-assisted therapy | Change in behaviour towards dog* (some more, some less approach behaviour towards dog); no change in relationship skills |
| Nevins (2013) | Pre-post | 1 | 1m/0f | 52 | War | Horses | Certified trainer | Intervention (Saratoga WarHorse Connection method) | Reduced PTSD symptomatology (clinically significant); improvements in depression, resilience, life satisfaction and social support |
| Rodriguez (2018)c | Control | 73 (45/28) | 59m/14f | M = 37.08, SD = 7.81 | War | Dogs | NA | Psychiatric service dog | Higher cortisol awakening response*; better health status*; no effect on sleep quality |
| Woodward (2017)d | Pre-post | 18 | 18m/0f | M = 39, SD = 13 | War | Dogs | NA | Service canine | Attenuated attentional bias towards images of aversive emotive scenes* or angry faces* |
| Woodward (2017)d | Pre-post | 23 | 23m/0f | M = 39, SD = 13 | War | Dogs | NA | Service dog | Lower sleep heart rate* and greater morning restedness* in presence of the service dog |
| Wortman (2018) | Pre-post | 1 | NR | NR | War | Seals | Representative from the VMARC (Veteran and Military Affiliated Research Center) | human–animal interaction | Reduced PTSD symptomatology (clinically significant) |
| Yarborough (2017) | Pre-post | 20 | NR | 23–67, M = 42, SD = 12 | War | Dogs | NA | Service dog | Reduced PTSD symptomatology*; improvements in VR-12 mental component summary*; BASIS depression/functioning subscale*; emotional lability subscale*; activity level*; happiness score* and quality of life*; moderate effect sizes for BASIS substance abuse and interpersonal relationships subscales |
| Yorke (2013) | Pre-post | 4 | NR | 8–10 | Not specified | Horses | NR | human–animal interaction | Mild to moderate symmetry between child-horse pairs |
N: number of analysed participants in the study; M: mean; SD: standard deviation; NR: not reported; NA: not applicable; AAI: animal-assisted intervention; AAT: animal-assisted therapy; a,b,dboth publications refer to the same study; csame study as O’Haire et al. (2015); esome studies report gender only for included participants and not for the number of analysed participants; * statistically significant.