Researchers at the University of Portsmouth have made groundbreaking strides in understanding horse emotions through their facial expressions. They’ve developed an innovative ethogram—an anatomically-based catalog that decodes how horses communicate feelings such as playfulness, aggression, curiosity, and alertness.

This pioneering study, published in the journal PeerJ, provides a vital resource for both scientists and practitioners in the field of equine welfare.

Utilizing the Equine Facial Action Coding System, the research team meticulously documented 805 distinct facial displays across 22 behaviors, which range from friendly gestures to signs of conflict. By linking each facial movement to specific muscle actions, they achieved a precise and objective method for analyzing equine expressions. A newly devised statistical tool allowed the researchers to explore how these expressions cluster according to various social situations.

Dr. Leanne Proops, an Associate Professor of Animal Behaviour and Welfare, stated, "This is the first systematic documentation of how horses combine facial movements into significant expressions. It opens up exciting new avenues for understanding equine emotions and enhancing their welfare."

Decoding Equine Emotions: What the Study Reveals

The study uncovered that horses employ an array of facial signals depending on their circumstances. Here’s a closer look at these incredible insights:

1. Signs of Aggression: The Agonistic Interactions

In aggressive encounters, horses display clear signs such as flattened ears angled back, raised inner brows, dilated nostrils, and lowered heads. These facial cues are crucial for preempting conflicts, allowing others to recognize and avoid potential aggression.

2. Attention States: The Curious Horse

When a horse is alert or curious, you’ll often see its ears perked up and forward. They also exhibit increased blinking and adjust their head positions to maximize sensory input, like tilting upwards to enhance visual engagement.

3. The Surprising Neutrality in Friendships

Interestingly, during friendly interactions, horses may adopt neutral expressions rather than the commonly assumed 'ears forward' stance. This suggests that a calm demeanor can indicate a positive mood, pointing to the necessity of understanding the broader context of their behavior.

4. Unleashing Playfulness

Playful horses showcase a fascinating variety of facial expressions, from relaxed lower lips and raised chins to wide-open mouths and noticeably rotated ears. Some facial movements in playful horses closely resemble the joyful expressions observed in primates and carnivores, hinting at a shared evolutionary backdrop among mammals.

Dr. Kate Lewis, the lead author, emphasized, "While horses often exhibit consistent facial movements across various contexts, the specific combinations and intensities vary significantly. This flexibility highlights the importance of looking at the entire body and environment to accurately decode equine behavior."

A Unique Find: The Discovery of AUH21

Among their findings, the researchers identified a previously undocumented facial movement termed AUH21, linked to the platysma muscle. This action tightens the side of the face, accentuating underlying structures, and has only been recorded in humans and gibbons so far. Its discovery could pave the way for better understanding of emotional states and pain in horses.

With approximately 60 million horses globally, these findings have profound implications for equine welfare, training practices, and veterinary care. This comprehensive framework allows those who work with horses to better interpret and respond to their emotional needs.

Dr. Proops remarked, "This research is revolutionary for anyone involved with horses. It equips us with a new perspective on their behavior, ultimately fostering better care and enhancing the bond between humans and these magnificent animals."