PSII-12 The effect of the diffusion of geranium and clary sage essential oils on relaxation responses in horses

Abstract Aromatherapy has been used in holistic medicine to improve relaxation in humans; however, there are limited studies on its use in horses. This study investigated the potential of aromatherapy on relaxation responses in horses using two common essential oils geranium (Pelargonium asperum) and clary sage (Salvia sclarea). We hypothesized that aromatherapy using essential oils would improve relaxation responses in horses. Geranium aromatherapy (GA) and clary-sage aromatherapy (CA) were tested against a control (CO; deionized water only) in a replicated 3 x 3 Latin square with three treatments, three horses (584 ± 9 kg of body weight and 11 ± 1 yr old), and three experimental periods. The experiment was replicated using the same horses, and the two experimental replicates were considered the square blocking factor. Aromatherapy session involved a 5-min acclimation period followed by 15 min of aromatherapy using a diffusor. Heart rate and respiration rate at min 0, 7 and 15, and average counts for body position and facial expressions from min 0 to 7 and from 7 to 15 (early and late session, respectively) were used as measure of relaxation. Aromatherapy improved eye expression over time (P = 0.01), with GA and CA horses showing significantly increased durations of relaxed eyes from early to late session (2.8 min vs. 5.3 min for GA and 3.7 min vs. 4.8 min for CA), while horses on CO showed reduced duration from early to late session (2.7 min vs. 1.2 min), indicating increased level of alertness and tension. Aromatherapy tended (P = 0.07) to improve ear expression. Horses receiving CA tended to show longer durations of relaxed ears compared with CO (4.33 min vs. 1.25 min), while GA (3.25 min) did not differ from CA and CO. Aromatherapy did not affect (P > 0.05) measures of body posture and heart and respiratory rates. Although not all relaxation responses were improved by aromatherapy, the results indicate that aromatherapy has potential for improving relaxation in horses as indicated by facial expressions.