Table 2 Quantitative results for equine-assisted services incorporated into substance use disorder treatment

Atherton et al., 2020 [25]

Compared pretest and posttest measures after study participants completed 6-session equine-facilitated psychotherapy (EFP) group intervention.

Adolescent Behavior Survey

There was a statistically significant difference between participants' pretest and posttest results for all seven categories of the Adolescent Behavior Survey: “support of others,” “encouraging others,” “listen to others,” “accepting of others,” “trusting of others,” “respectful of others,” and “work cooperatively with others” (p < 0.001).

PHQ-9

There was a statistically significant difference between participants' pretest (M = 17.00, SD = 2.16) and posttest (M = 10.20, SD = 1.55) PHQ-9 results (t(9) = 18.94, p < 0.001).

GAD-7

There was a statistically significant difference between participants' pretest (M = 9.80, SD = 1.23) and posttest (M = 4.60, SD = 1.90) GAD-7 results (t(9) = 13.38, p < 0.001).

Gatti et al., 2020 [30]

Compared to patients that received treatment as usual (TAU)^a only.

Treatment Completion

A non-statistically significant larger percentage of participants in the complementary horse-assisted therapy (cHAT) group completed their assigned program (44%) than the TAU-only group (32%).

Dropout

Slightly fewer participants in the cHAT group dropped out of treatment (22%) than the TAU-only group (26%). There was no significant association between participants receiving intervention compared to TAU and dropout relative to completion (OR: 0.60, 95% CI 0.11–3.25, p = 0.553).

Transfer to Another Treatment

Fewer participants in the cHAT group were transferred to another treatment (28%) than the TAU-only group (42%). There was no significant association between participants receiving intervention compared to TAU and transfer relative to completion (OR: 0.47, 95% CI 0.10–2.19, p = 0.335).

Time in Treatment

There was no statistically significant difference in time in treatment between the cHAT group and the TAU-only group (mean 98.7 days, SD = 5.6 vs mean 107.4 days, SD = 23.65, p = 0.237).

Attendance at the HAT Program

There was no statistically significant association between horse-assisted therapy (HAT) attendance (attending eight sessions or more) and treatment completion (OR: 3.000, 95% CI 0.211–42.65, p = 0.408).

Kern-Godal et al., 2015 [31]

Compared to patients that received TAU^a only.

Time in Treatment

HAT participants remained in treatment for a significantly longer period of time than those who did not participate in HAT (mean 141 days, SD = 93.6 vs mean 70 days, SD = 73.8, p < 0.001). HAT participants were almost four times as likely to remain in treatment for 90 days or more (aOR 3.9 CI 1.7–8.8, p = 0.001).

Treatment Completion

After excluding time in treatment and controlling for age, sex, education, number and severity of substances used, psychological distress and temporary exits, the aOR for HAT participants completing treatment was 8.4 (95% CI 2.7–26.4, P < 0.001).