The neurobiological basis of emotions and their connection to facial expressions in non-human mammals: insights in nonverbal communication.
Authors: Mota-Rojas Daniel, Whittaker Alexandra L, Bienboire-Frosini Cécile, Buenhombre Jhon, Mora-Medina Patricia, Domínguez-Oliva Adriana, Martínez-Burnes Julio, Hernández-Avalos Ismael, Olmos-Hernández Adriana, Verduzco-Mendoza Antonio, Casas-Alvarado Alejandro, Lezama-García Karina, Grandin Temple
Journal: Frontiers in veterinary science
Summary
# Editorial Summary Understanding how horses and other mammals communicate their emotional states through facial expressions relies on the same neurobiological pathways—the limbic system, amygdala, and motor cortex connections—that govern these responses in humans, making observable facial changes a genuinely reliable window into affective state rather than mere anthropomorphic interpretation. Researchers have adapted the human Facial Action Coding System (FACS) into AnimalFACS, a standardised anatomical framework now validated for eight species including horses, dogs, cats, and primates, allowing objective documentation of specific facial muscle movements rather than subjective emotional labelling. Recent neurobiological evidence demonstrates that equines and other mammals actively modify their facial expressions in response to different emotional contexts, with specific muscle contractions and relaxations correlating to positive or negative affective states—a capacity previously underestimated in veterinary practice. For equine professionals, this framework offers a practical tool to move beyond intuition when assessing a horse's true emotional response to training, handling, medical procedures, or environmental stressors, potentially revealing distress or contentment that verbal communication cannot convey. Systematically recognising these coded facial expressions could substantially improve handling protocols, training methods, and welfare assessment, whilst also enhancing the precision of behaviour-based research in equine science and allowing more nuanced communication between horse and handler.
Read the full abstract on PubMed
Practical Takeaways
- •Learning to read equine facial expressions using AnimalFACS principles (ear position, eye aperture, mouth tension) can help you objectively assess whether a horse is experiencing positive or negative emotions during handling, treatment, or training
- •Facial expression analysis provides an objective, non-invasive tool to monitor your horse's affective state and welfare in real-time without relying solely on behavioural or physiological indicators
- •Understanding the neurobiological basis of equine emotions supports better horsemanship by enabling you to recognize and respond appropriately to subtle signs of stress, pain, fear, or contentment
Key Findings
- •Facial expressions in non-human mammals are controlled by converged neural pathways from the amygdala, motor cortex, and facial nerve that reflect internal emotional states
- •AnimalFACS is an adaptation of the human Facial Action Coding System validated for eight animal species including horses, dogs, cats, and non-human primates
- •Facial muscle contractions/relaxations can be objectively coded and associated with positive or negative emotional responses to specific contexts
- •Recognition of animal sentience and facial expression analysis may improve human-animal communication and welfare assessment