Scientists from England have created the first anatomically-based descriptions (ethogram) of equine facial behaviour, mapping how horses use their faces to communicate emotions like playfulness, aggression, curiosity, and attention.
The full ethogram (database) and analyses—published in PeerJ—offer a valuable resource for researchers and practitioners.
Using the Equine Facial Action Coding System, researchers at the University of Portsmouth, England, catalogued 805 facial displays across 22 distinct behaviours, ranging from friendly interactions and play to conflict. Each facial movement was linked to specific muscle actions, allowing for precise, objective coding. The team also applied a new statistical tool to analyse how these expressions cluster in different social contexts.
The study revealed that horses use a variety of facial cues depending on the situation. For example, playful interactions involve a dynamic range of facial movements, including depressed lower lips, raised chins, parted lips, wide-open mouths, rotated and flattened ears, increased visibility of eye whites, and noses pushed forward.
Some play expressions bear remarkable similarity to the open-mouth play faces observed in primates and carnivores, suggesting a deep-rooted evolutionary basis for such behaviors across mammalian species.
“We found that horses often use the same facial movements across different contexts, but the combinations and intensities vary,” lead author Dr Kate Lewis said.
“This flexibility underscores the importance of considering the whole body and context when interpreting equine behaviour.”
With nearly 60 million horses worldwide, this research has significant implications for equine welfare, training, and veterinary care. By providing a detailed framework for interpreting facial expressions, it can help handlers and professionals better understand and respond to horses’ emotional states.
