Eight horses were used in a crossover study and were transported for 15 minutes in a horse trailer. During the trailer ride, the horses received water aromatherapy as the control, and lavender aromatherapy, such as that provided by HorseScents, as the treatment. Three measurements of heart rates and blood draws were taken on each horse: (1) baselined before loading into the trailer, (2) stressed immediately after the trailer ride, and (3) recovery- 50 minutes after the trailer ride.

In the control and treatment horses, there was a difference in cortisol levels, which provides evidence to conclude that cortisol levels were lower in horses that were subjected to lavender aromatherapy during a stressor.