Ethogram for understanding horse emotions and social behaviour

(c) Golop Dreamstime.com

 Researchers at the University of Portsmouth’s Centre for Comparative and Evolutionary Psychology have developed the first anatomically-based ethogram of equine facial behaviour, offering a tool for understanding how horses communicate through facial movements. This ethogram—essentially a structured catalogue of facial actions—captures how domestic horses use their faces to convey emotions such as curiosity, aggression, playfulness, and attentiveness across a variety of social contexts.

Unlike the term “facial expression,” which often implies an associated emotion, the researchers have deliberately used the term facial behaviour. This distinction acknowledges that while some facial movements may correlate with emotional states, not all facial changes are necessarily expressive in the emotional sense. This neutral terminology allows for more objective observation and coding of equine facial movements.

 

The aim of the study was to develop an ethogram of equine facial behaviour observed during horse-horse interactions. These interactions were categorised into affiliative (non-play), play, agonistic (conflict), and attentional contexts. Using the Equine Facial Action Coding System (EquiFACS)—an established method that links visible facial changes to specific underlying muscle movements—the researchers documented 805 facial expressions across 22 distinct behaviours.

 

Crucially, they employed a novel statistical tool to analyse how these facial actions cluster in different social scenarios, providing new insights into the functional roles of facial behaviour in equine communication.

 

The study revealed that horses exhibit a wide and nuanced range of facial behaviours depending on the social context:

 

Agonistic Interactions
Aggressive or conflict-based interactions were marked by flattened, backward-facing ears, inner brow raisings, nostril dilation, and head-lowering. These signals offer clear warnings of potential escalation, helping horses (and human observers) anticipate and de-escalate conflict.

 

Attentional States
When alert or investigating their environment, horses displayed forward-pointing, closely positioned ears. Additional markers included increased blinking or half-blinking, and head positions that facilitated sensory focus, such as lifting the head to enhance visual attention.

 

Friendly Interactions
Interestingly, affiliative interactions were often characterised by relatively neutral facial behaviour. Contrary to the common belief that ears forward indicate positive emotion, this was not consistently observed. This suggests that minimal facial movement in these contexts may actually signal comfort and positive mood—highlighting the importance of considering the broader behavioural and social context.

 

Play Behaviour
Playful interactions involved the most dynamic facial displays, including dropped lower lips, raised chins, parted lips, open mouths, flattened or rotated ears, prominent eye whites, and forward-thrust nostrils. Many of these expressions resemble the open-mouth play faces seen in primates and carnivores, supporting the idea of a shared evolutionary origin for certain play behaviours across mammalian species.

 

“We found that horses often use the same facial movements across different contexts, but the combinations and intensities vary,” explained Dr Kate Lewis, lead author. “This flexibility underscores the importance of considering the whole body and context when interpreting equine behaviour.”

 

One of the most intriguing findings was the identification of a previously unrecorded facial movement, designated as AUH21, involving the platysma muscle. (The platysma muscle  is a thin, superficial muscle located just beneath the skin. It extends along the side of the face and neck, originating from the region near the ear and inserting into the skin of the neck and shoulder. Its primary function is to move the skin, aiding in facial expressions and helping to twitch the skin to repel insects.)This movement causes tightening on the side of the face, making the underlying anatomical structures more visible. AUH21 has previously only been documented in humans and gibbons, making its discovery in horses significant for comparative biology. It may also offer new avenues for evaluating emotional states and pain indicators in equine clinical settings.

 

By providing a scientifically validated reference for interpreting equine facial behaviour, the ethogram is poised to become a vital resource for equine veterinarians, behaviourists, trainers, and students of equine science.

 

“This is the first time we’ve been able to systematically document how horses combine facial movements into meaningful expressions,” said Dr Leanne Proops, Associate Professor in Animal Behaviour and Welfare. “It opens up new possibilities for understanding equine emotions and improving welfare.”

 

The study is published in PeerJ, along with the full ethogram and supporting analyses, offering a robust framework for further research and practical application.

 

“This work is a game-changer for anyone working with horses,” Dr Proops added. “It gives us a new lens through which to view and interpret their behaviour, ultimately leading to better care and stronger human-animal relationships.”

 

For more details, see: 

 

Lewis K, McBride SD, Micheletta J, Parker MO, Rincon AV, Wathan J, Proops L.(2025). 

An ethogram of facial behaviour in domestic horses: evolutionary perspectives on form and function. 

PeerJ 13:e19309

https://doi.org/10.7717/peerj.19309

Impact of turnout rugs on horse behaviour: a study under mild weather conditions

(c) Mike Taylor | Dreamstime.com

Rugging horses is a widespread practice, commonly used to keep them warm and dry in cold, wet weather or to protect them from insects and sunlight in warmer conditions. However, rugs may also pose drawbacks — potentially causing thermal discomfort or restricting natural behaviours such as grooming and movement.

Despite the routine use of rugs, especially in the UK where spring and autumn bring relatively moderate weather, few studies have examined how horses behave with and without rugs in such conditions. A recent study by Frederick Daw and colleagues at the Royal Veterinary College, London, aimed to address this gap. The research, published in Applied Animal Behaviour Science, provides evidence that can help owners make more informed decisions about rug use to support equine welfare.

The study involved ten healthy horses, all accustomed to wearing rugs, from two different yards in southern England. Each horse was observed during 30-minute sessions, with and without a turnout rug, across several weeks. A total of 172 observation sessions were carried out, ensuring that each horse experienced both conditions in roughly equal measure.

Weather conditions during the study ranged from 1°C to 15°C, with wind speeds of 6 to 15 mph. Importantly, no signs of heat or cold stress were noted in any horse throughout the study period. The researchers analysed behavioural data using Generalised Estimating Equations (GEE), a statistical method that accounts for repeated measures on the same individuals.

The results showed a mix of both positive and negative effects associated with rugging:

·       Reduced insect-related behaviour: Horses wearing rugs exhibited significantly less tail swishing and head shaking, behaviours commonly linked to fly or midge irritation. Midges (Culicoides spp.) were observed at both sites, particularly when temperatures were higher and winds lower - conditions known to favour insect activity. These findings suggest that turnout rugs may offer effective protection against insect harassment under mild weather conditions.

·       Increased grazing at one site: At one of the two study locations, rugged horses spent more time grazing. This may reflect reduced fly irritation or increased comfort when wearing rugs.

However, the study also highlighted potential concerns:

·       Reduced movement and grooming: Horses wearing rugs were observed to walk less and perform fewer self-grooming behaviours. Both activities are considered important for physical health and psychological well-being. Their reduction may indicate that the rugs, though protective, imposed some physical restriction or discomfort  - possibly due to their weight or design.

·       Site-specific differences: The effects of rugging varied significantly between the two locations, suggesting that environmental factors and management practices also influence how horses respond to being rugged. Therefore, caution is needed when generalising these findings to other settings.

Tail swishing was found to increase with temperature (by 1.33 swishes per 1°C) and decrease with windspeed (by 0.84 swishes per 1 mph). These results further support the conclusion that environmental conditions - particularly warmth and still air - are key drivers of insect-related behaviours in horses.

This study indicates that during mild weather conditions (above 5°C), lightweight turnout rugs may help reduce insect-related discomfort in horses. However, rug choice matters: heavier or poorly fitting rugs may inhibit natural behaviour, outweighing any protective benefits.

The researchers conclude:

“When weather conditions are relatively mild (above 5 °C), horse welfare may be improved more by the use of lightweight turnout rugs for fly protection rather than heavyweight rugs designed primarily for warmth.”

They also call for further studies to test this idea more directly — in particular, by assessing the impact of purpose-designed fly rugs under mild autumn conditions, as opposed to standard waterproof turnout rugs.

For more details, see:

 

Frederick Daw, Charlotte Burn, Yu-Mei Chang, Christine Nicol,

Effect of turnout rugs on the behaviour of horses under mild autumn conditions in the United Kingdom,

Applied Animal Behaviour Science, (2025) vol 288,106661

 

https://doi.org/10.1016/j.applanim.2025.106661

Vets with Horsepower hit the road again – This time for "The Italian Job"

The motorbiking team of equine vets known as Vets with Horsepower are revving up once more
for another epic charity mission—this time through Italy and Switzerland on their latest tour, aptly named "The Italian Job."

This dedicated group of experienced equine veterinarians and lecturers combine their passion for motorcycles with their commitment to continuing professional development (CPD) and charitable giving. Since their first tour in 2010, which covered all the UK veterinary schools at the time, they’ve been delivering affordable, high-quality CPD lectures while raising money for great causes - often covering hundreds of miles a day by bike to do so!

This year’s journey kicks off on 8th July in Lodi, Italy. From there, the team will visit:

·       Perugia

·       Sassari

·       Pisa

·       Zurich, Switzerland
...before wrapping up the adventure in Saarlouis, Germany on 17th July.

Even if you're not in Italy, you can still take part. On 8th July 2025, the team will be delivering a full day of top-tier equine CPD lectures in Lodi – and the event will also be live-streamed globally for online attendees.

Your registration fee (just £10 minimum) gives you access to:

·       Live streaming of the lectures on 8th July

·       On-demand access to the recorded sessions from 10th July until 31st August 2025

All proceeds go directly to support these five outstanding charity projects:

·       Saving the Survivors – providing veterinary care to animals affected by poaching in Africa

·       The Gambia Horse and Donkey Trust – supporting working equids and their owners through vet care and education

·       Mozambique Veterinary School – training the next generation of vets in Southern Africa

·       Changing Lives Malawi – improving education and opportunities for children

·       Shy Lowen Horse and Pony Sanctuary – offering rescue and rehabilitation for horses and therapeutic services for people

Please consider donating more if you’re able—every extra pound (or dollar) makes a real difference.

https://www.vetswithhorsepower.com/2025.html

Strangles survey participants sought

Pharmaceutical company Dechra has launched a UK-wide survey aimed at increasing awareness of strangles, one of the most contagious equine diseases, and encouraging best practices in its prevention and control.

 

The short survey—designed to take just a few minutes—seeks to gather insights from horse owners about their experiences with strangles. It includes questions about disease prevention measures, biosecurity practices, and vaccination awareness.

 

Participants are also encouraged to share their opinions and personal views on strangles, helping to shape future strategies for disease control and support across the equestrian community.

 

To take part in the survey, visit: https://bit.ly/3H1o6bj

Managing insulin dysregulation in horses: a role for nutraceuticals

(c) Brian Sedgbeer Dreamstime.com

Insulin resistance (IR) and insulin dysregulation (ID) in horses are major risk factors for developing laminitis; a painful and potentially debilitating condition. While some horses are genetically predisposed to IR, diet also plays a critical role in its development. Because of this, there's growing interest in whether specific dietary strategies, including the use of nutraceuticals, can help reduce the risk.

A recent study led by Caroline Loos and her colleagues at the University of Kentucky's Gluck Equine Research Center, and published in the journal Animals,  explored whether supplementing the diet with a specific combination of nutrients could help improve insulin regulation in horses that are prone to IR. 

The trial involved 16 mature horses with a known history of insulin dysregulation. The horses were split into two groups:

• One group received a nutraceutical supplement containing omega-3 fatty acids, glutamine, vitamin E, and active yeast.
• The other group received a placebo.

Both supplements were given once daily for four weeks. During the study, horses were kept on dry lots, had free access to grass hay, and were also fed a grain concentrate twice daily (providing 0.5 g of starch per kg of body weight per meal).

To assess the horses’ insulin regulation, each underwent a Combined Glucose–Insulin Tolerance Test (CGIT) at the start and end of the trial. The CGIT is a diagnostic test commonly used in equine medicine to evaluate how effectively a horse’s body clears glucose from the bloodstream in response to insulin. During the test, horses receive a bolus (injection) of glucose and insulin, and blood samples are collected over a 150-minute period to track how quickly glucose and insulin levels return to baseline. The faster the return to normal, the better the horse’s insulin sensitivity.

After four weeks of supplementation, horses receiving the nutraceutical showed notable improvements:

• 61% faster glucose clearance compared to the placebo group.
• Shorter time for blood glucose levels to return to normal.
• Lower insulin levels at 75 minutes post-test, indicating reduced hyperinsulinemia.
• Glucose concentrations were also lower at 45 minutes post-test in the supplemented group.

In contrast, horses in the placebo group still had elevated insulin levels 150 minutes after the test, suggesting poorer insulin regulation.

These findings suggest that prophylactic use of specific nutraceuticals may help improve insulin sensitivity and reduce the risk of insulin-associated laminitis, particularly in horses consuming high-starch diets. By supporting faster glucose clearance and lowering insulin levels, this approach may offer a valuable management tool for horses at risk of ID or IR.

While more research is needed to confirm long-term benefits, this study highlights the potential of targeted dietary supplementation in supporting metabolic health in horses.

 

For more details, see:

 

Loos, Caroline, Annette Castelein, Eric Vanzant, Emma Adam, and Kyle R. McLeod. 

Nutraceutical Supplement Mitigates Insulin Resistance in Horses with a History of Insulin Dysregulation During a Challenge with a High-Starch Diet

Animals (2024) 14, no. 23: 3385. 

https://doi.org/10.3390/ani14233385

New device aims to help asthmatic horses breathe more easily

The new equine respirator (Tim Brouk)

A novel collaboration between Purdue University’s College of Health and Human Sciences and the College of Veterinary Medicine may offer significant relief for horses suffering from asthma—a common respiratory condition often triggered by inhaled particles such as mould spores found in dusty hay.

Equine asthma, like its human counterpart, is frequently linked to allergic sensitisation to airborne irritants. While a range of treatment and management options exist, the most effective strategy remains straightforward: minimise exposure to the particles that trigger the condition. This is typically attempted by soaking or steam-treating hay to reduce airborne dust. However, researchers at Purdue have taken this one step further by developing a wearable device that could filter out harmful particles before they even reach the horse’s airways.

At the heart of this innovation is an equine respirator—a specially designed breathing mask that attaches directly to a horse’s bridle or head collar. The device allows the horse to breathe filtered air through an intake positioned over the bridge of the nose, while exhalation occurs through valves located near the nostrils. Crucially, the design allows horses to eat and drink while wearing the respirator, making it suitable for continuous use in dusty environments like stables or arenas.

The project was born out of a cross-disciplinary partnership. Dr. Jae Hong Park, associate professor of Health Sciences, had been working on developing human respirators, especially for welders working in manufacturing facilities. His research caught the attention of Dr. Laurent Couëtil, a professor of Large Animal Internal Medicine in the College of Veterinary Medicine, who wondered if a similar approach could be adapted for equine use.

Momentum built when Chang Geun Lee, a Ph.D. candidate in Health Sciences with a background in mechanical engineering and industrial design, joined Park’s lab. Lee brought a unique combination of technical skills and practical design experience that proved instrumental in creating a functional and comfortable respirator for horses.

The team, which also includes Laura Murray, RVT and research technologist in the Department of Veterinary Clinical Sciences, spent months designing, prototyping, and refining the respirator. Their efforts have culminated in a practical tool that could significantly improve the quality of life for horses affected by respiratory issues—particularly those regularly exposed to dusty environments.

By combining expertise in health sciences, veterinary medicine, and engineering, this collaboration exemplifies the power of interdisciplinary research to solve real-world problems—and could mark a significant advance in the management of equine asthma.

The research team are now looking to see if the device could be made available for general use.

For more details, see: 

https://vet.purdue.edu/news/asthmatic-horses-can-breathe-easier-thanks-to-purdue-health-and-human-sciences-and-college-of-veterinary-medicine.php