Quantifying facial expressions of the horse with optical motion capture and surface electromyography; a proof of concept

Facial expressions can be assessed to study emotional expression in horses, though existing tools often depend on subjective judgement. This study explores two methods to quantify facial expressions of horses through recordings of muscle activity and skin movement. Surface electromyography and optical motion capture were used to measure muscle activity of the m. frontalis and upper eyelid movement. Facial expressions in the eye region were successfully captured by both methods in a non-invasive way.