Beneficial effects of Lavender (Lavandula angustifolia Mill.) essential oil application prior a stressful situation in horses

Horses are gregarious and fearful animals that undergo many stressful situations by humans. Simple and soft means are needed to manage their stress. This study was set up to investigate the relaxing effects of some EO on horses. The calming and soothing effects of Lavender (Lavandula angustifolia Mill.) essential oil (LaEO) have been widely demonstrated. The LaEO mode of action is essentially due to two major active molecules: linalool and linalyl acetate. The objective of this study was to develop an experimental protocol to highlight the effects of EO on equine stress response and to validate the effects of LaEO applied ante stress. Twenty-eight Welsh fillies were divided into two groups: one treated with 2 ml of vegetable oil (control), the other treated with 10% LaEO applied with a roll-on around the nostrils. The fillies were subjected to a series of tests of 30 min during which the heart rate (HR) and different behavioral indicators of stress were noted. Salivary cortisol was also measured. Indicators of stress such as HR, alert postures and defecations measured during some tests are significantly lower in the LaEO group than in the control group. These results and salivary cortisol content show that the application of LaEO reduced the level of stress of animals placed in stressful situations. Furthermore, blood samples taken from 6 horses show that the pharmacokinetics of linalool in plasma presented a peak 20 min after LaEO application, agreeing with the effect of LaEO during the tests. In addition, a peak of antioxidant effectiveness appeared in the plasma 50 min after LaEO application. These data should encourage the use of this protocol with LaEO in further studies to optimize the effective dose, and possibly to assess other EO which could help horses to manage stressful situations.