June 4, 2025, 3:37 pm | Read time: 4 minutes
What Facial Expressions Do Horses Show When Playing or Looking for a Fight? A study reveals how sensitively and diversely horses use their facial muscles to communicate with their peers. They display expressions that show surprising parallels to other mammals, including humans. The findings offer new opportunities for research, animal welfare, and everyday interactions with horses.
Facial expressions and their associated meanings have long been a topic that received little attention in science. However, research into gestures and facial expressions has rapidly uncovered new insights in recent years–including for dogs and cats. A study has now examined the facial expressions of another domesticated animal species and, for the first time, provided comprehensive findings on the faces of horses.
Horses Also Have a “Play Face”
Facial expressions–or more neutrally termed “facial behavior” in this study–are a central component of nonverbal communication in social animals. Especially in group-living species like horses, precise facial expressions can provide clues about the animal’s internal state or intentions. Until now, this aspect had not been well-researched in horses. There were only a few studies on the “pain face,” which helps owners better recognize suffering in their animals.
A research team led by Kate Lewis from the University of Portsmouth has, for the first time, created a comprehensive, scientifically-based behavioral inventory (ethogram) of domestic horse facial expressions. The study was conducted at the Sparsholt College Equine Centre in the United Kingdom and is based on the analysis of 805 documented facial expressions during social interactions. The work was published on May 28, 2025, in the journal “PeerJ.” The researchers used the established Equine Facial Action Coding System (EquiFACS) and expanded it with a new, previously unknown facial unit.
The researchers provide a complete, context-based overview to enhance understanding of the diversity of facial expressions in horses. They paid particular attention to how horses use their facial muscles depending on the situation to send specific signals–such as during play, attention, aggression, or friendly contact.
Study Describes How Horses Express Four Emotional States Through Facial Expressions
Thirty-six domestic horses (12 mares, 24 geldings) aged 5 to 19 years were studied. Over a period of 24 days in the fall of 2020, the team documented a total of 72 hours of horse behavior in the pasture. Using high-resolution video recordings, moments of social interaction were captured and then coded with EquiFACS–a system that categorizes facial muscle movements into “Action Units” (AUs) and “Action Descriptors” (ADs).
The researchers focused on four social contexts: friendly interactions, play, aggressive behavior, and attention responses. For each observed facial movement, the exact muscle actions involved were determined. Additionally, the network analysis tool NetFACS was used to identify characteristic patterns. Ethical approval was obtained.
The researchers identified a total of 805 combined facial behaviors from 22 observed social behavior forms. The facial expressions varied significantly depending on the context:
- Play: Characteristic was a combination of an open mouth (mouth stretching), lowered lower lip, raised chin, and visible eye whites. The protrusion of the nose was also particularly common.
- Aggression: Typical were ears turned backward and downward, flared nostrils, lowered head, and a new feature, the tense cheek muscles.
- Attention: Forward-facing ears and pinched ears were prominent, accompanied by an increased blink rate and head raising.
- Friendly Interaction: Less specific patterns, but often the protrusion of the nose, slightly open mouth, and occasional blinking.
Particularly noteworthy was the discovery and definition of a new facial unit: the tense cheek muscles, which had never been documented in horses before. This describes a tension of the platysma muscle, leading to a visibly tightened facial area between the cheek and mouth.
“If You Blink, I’ll Blink Back!” How Dogs React to Other Dogs
Human and Horse Hearts Beat in Sync During Animal-Assisted Therapy
Can dogs laugh? Biologist gives an answer
Deciphered Horse Facial Expressions a Breakthrough in Behavioral Biology
This pioneering study provides, for the first time, a complete, behavior-based inventory of domestic horse facial expressions–a breakthrough for comparative behavioral biology. The results show that horses have a very differentiated facial expression that is used flexibly and contextually. It was also documented how closely their expressions are related to those of other mammals.
Especially the similarities between the so-called “play face” of horses and similar expressions in primates and carnivores (such as dogs, wolves) suggest that this behavioral pattern is deeply rooted in mammalian development. The introduction of the “tense cheek” feature into EquiFACS further expands the possibilities for capturing horse emotions more precisely–including in relation to pain or stress. In the long term, this could significantly improve the use of facial expression analyses in veterinary medicine, behavioral research, and animal welfare.
Future investigations must show whether these four behaviors are used by all horses of all ages or if they are learned behaviors. It also needs to be examined whether horses show these facial expressions more or less in interaction with humans. Due to the selection of domesticated and often castrated horses, aggressive behaviors were relatively rare to observe. In this context, it would be interesting to investigate whether intact stallions also exhibit this and whether wild horses communicate in a similar way. 1