What riding school horses' faces reveal about their experience

  

© Igordabari  Dreamstime.com

   

Horse owners are often taught to watch for obvious signs of discomfort, such as pinned ears, tail swishing, bucking or resistance under saddle. But what if a horse's face could reveal more subtle clues about how it is coping long before those more obvious behaviours appear?

New research from the University of Guelph suggests that tiny changes in facial expression may provide valuable insights into how lesson horses experience their work and interactions with riders.

 As part of her PhD research in Equine Exercise Physiology, Aveil Oberhammer used the Equine Facial Action Coding System (EquiFACS) to study the facial expressions of 35 riding school horses before, during and after both beginner and advanced hunter/jumper lessons. Unlike the Horse Grimace Scale, which was developed specifically to identify pain, EquiFACS is a comprehensive system that records individual facial muscle movements without assigning them an emotional meaning. Researchers can then investigate what those movements may indicate in different situations, from learning and communication to stress and welfare.

The study examined short video clips taken at five stages of a typical lesson: before tacking up, after saddling, after bridling, immediately after riding and following untacking. A certified EquiFACS observer analysed each clip, recording facial action units including eye movements, ear position, nostril shape and oral behaviours such as chewing and lip movements.

Some facial expressions are surprisingly difficult to interpret. Chewing, for example, has traditionally been viewed as a sign of relaxation, yet growing evidence suggests it may instead function as a self-soothing behaviour that helps horses regulate their emotional state. Similarly, nostril dilation may reflect physical exertion, heightened attention or anticipation depending on the circumstances.

"You need to be very observant," Oberhammer explained. "Doing it live is much harder than analysing video. Sometimes you're trying to determine whether a tiny lip movement is upwards or backwards because that changes the facial action score."

One of the study's key questions challenged a common assumption within riding schools: that beginner riders are easier for horses because the physical demands are generally lower. The findings suggest the reality is more complex.

Overall, rider ability alone had surprisingly little effect on the horses' facial expressions. However, certain groups of horses responded differently. Less experienced lesson horses, particularly those with fewer than three years in a lesson programme, were more likely to display facial movements such as nostril lifting, nostril dilation and tongue movements when working with beginner riders. Mares also showed more facial activity than geldings and exhibited more eye blinks, nostril movements and lip parting with novice riders.

These findings may reflect the additional mental effort required to interpret inconsistent rider cues. Horses constantly attempt to understand what their riders are asking, and unclear timing or conflicting signals may increase their cognitive workload.

"We know that horses learn from trial and error," said Oberhammer. "If they don't associate a certain cue with a positive outcome, they might just do nothing."

The research also highlighted how facial expressions changed throughout the lesson itself. Horses were most expressive before preparation began, showing a variety of movements around the eyes, nostrils and mouth. Overall facial activity declined after saddling and became even more subdued once bridled. Following the ride, oral behaviours such as chewing became more common again, suggesting horses may communicate differently once tack and riding pressures are removed.

The authors conclude that the greatest changes in facial expression were linked not to rider ability but to different stages of the lesson, potentially reflecting anticipation before work and recovery or relief afterwards.

As equitation science continues to reshape understanding of horse behaviour and welfare, subtle facial expressions are emerging as another valuable tool for looking "behind the bridle". While they should never be interpreted in isolation, careful observation of these quiet signals could help riders, coaches and instructors better understand how horses experience their work, refine communication and support more horse-centred training and management practices.

 

For more details, see:

Aveil Oberhammer, Caleigh Copelin, Lais Rabel, Katrina Merkies

Behind the bridle: Understanding facial expressions in lesson horses before and after riding.

Applied Animal Behaviour Science,(2026) Vol 300,106982,

https://doi.org/10.1016/j.applanim.2026.106982

 

Interested in learning more about subtle behavioural cues, learning theory, and how horses communicate? Discover how the latest research in equine behaviour can help you better understand your horse and build stronger partnerships through informed, welfare-focused training.
Register for Equine Guelph’s 12-week accredited, online course Equine Behaviour, offered in partnership with School of Continuing Studies through the University of Guelph.  Go to:

https://courses.scs.uoguelph.ca/search/publicCourseSearchDetails.do?method=load&courseId=17912

 

 

Pseudomonas aeruginosa in horses and other animals

  

© CarolHancock Dreamstime.com

Pseudomonas aeruginosa is an environmentally widespread bacterium found naturally in soil and water. Although it
is often harmless in the environment, it is an important cause of disease in both human and veterinary medicine. The bacterium is particularly concerning because it possesses a high level of intrinsic resistance to many antibiotics, has a remarkable ability to adapt genetically, and can form resilient biofilms that protect it from both the host immune system and antimicrobial treatments.

 

The World Health Organisation (WHO) has designated P. aeruginosa as a "Priority Pathogen" due to its role in antimicrobial resistance. It is also one of the six bacterial species that make up the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). These bacteria are responsible for many hospital-acquired infections worldwide and are notorious for their ability to evade antibiotic treatment.

 

In horses, P. aeruginosa is associated with several important diseases, including genital tract infections, respiratory disease and ocular infections. In mares, infection can contribute to infertility and pregnancy-related problems, making it a significant pathogen in equine breeding operations.

 

To better understand the occurrence of P. aeruginosa in animal populations, Kellie Strickland and colleagues at the University of the Sunshine Coast, Australia, conducted a large-scale epidemiological study. The researchers analysed 1,669 DNA samples collected between 2010 and 2023 from a variety of healthy and diseased animals in South-East Queensland. The study included samples from wild birds, domestic animals, livestock, kangaroos and koalas.

 

Overall, the prevalence of P. aeruginosa was relatively low, with only 1.8% of all samples testing positive. However, livestock had the highest prevalence (4.5%), largely driven by horses, which showed a prevalence of 7.4%. This was considerably higher than the rates observed in wild birds (1.5%), koalas (1.6%) and other domestic animals (1.9%). No positive samples were detected in cattle or kangaroos.

 

Of particular concern was the detection of a genetic mutation known as GyrA Thr83Ile in two horse-derived P. aeruginosa samples. This mutation has previously been associated with resistance to fluoroquinolones, a class of antibiotics commonly used to treat P. aeruginosa infections in both humans and horses. Although the researchers were unable to confirm antibiotic resistance through laboratory culture and susceptibility testing, the presence of this mutation suggests that a resistant subpopulation may be emerging within the equine population.

 

The findings highlight the importance of ongoing surveillance of antimicrobial resistance in horses. While the overall prevalence of P. aeruginosa was low, the relatively high carriage rate in horses and the detection of a clinically important resistance-associated mutation warrant further investigation.

 

For more details, see:

Prevalence of Pseudomonas aeruginosa in Australian wild birds, native wildlife, livestock and domestic animals

Kellie R. Strickland, Martina Jelocnik, Erin P. Price & Derek S. Sarovich 

Scientific Reports (2026) vol 16, Article number: 15423 (2026) 

https://www.nature.com/articles/s41598-026-43853-6

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

Memory for dung sniffing

Horse dung (c) Avrezn Dreamtime.com

 Horses sniff dung for several reasons - for communication, social behaviour, and environmental awareness.  

Dung contains chemical cues that can convey information about the individual who deposited it, such as their identity, sex, and reproductive status. By sniffing dung, horses can recognize and gather information about other horses in their vicinity. It may also help horses understand social structures and hierarchies within a group, allowing them to recognize dominant individuals and avoid potential conflicts.

 

Horses may form "stud-piles" where they deposit dung in specific locations to mark their presence. This behaviour can communicate territorial boundaries or indicate that a particular area is frequently used by certain individuals or groups

 

Research by Audrey EM Guyonnet, and Ian Q. Whishaw, at the Canadian Centre of Behavioural Neuroscience, University of Lethbridge, Alberta looked at how horses use location , odour, and memory related to their encounters with dung.

 

In their study, which is reported in Behavioural Processes, they assessed the response of horses when they were led, at varying time intervals, to objects chosen by the experimenter or to dung deposits, which they were allowed to sniff.

 

Twenty-two horses were included in the study. which was carried out in a total of six riding arenas—two indoor and four outdoor. – 

 

The research team took video recordings of the horses encountering the objects and the dung Frame-by-frame video analysis assessed several factors: the way the horses approached the objects or dung deposits, the duration of sniffing, nostril use, ear position, and blinking associated with dung investigation.

 

The researchers found that horses consistently approached and sniffed dung deposits for a longer time compared to non-dung objects.

 

While they were sniffing, horses moved their heads across the dung deposits. They showed no specific nostril or ear preference when investigating the target and they tended to blink as they disengaged from sniffing.

 

Horses showed a reduced likelihood of approaching and shorter sniff durations when revisiting dung deposits encountered earlier the same day, regardless of the location. The researchers suggest that this indicates a strong short-term memory for dung and its location.

 

However, horses showed poor memory for dung visited on the previous day, suggesting that their memory for dung is good on the same day but significantly diminishes by the next day. This pattern reflects adaptive forgetting, allowing horses to focus on current environmental cues. (“Adaptive forgetting” refers to the brain's mechanism of intentionally forgetting certain information to optimise memory function and cognitive efficiency. It helps individuals prioritise relevant and important information while discarding outdated, irrelevant, or redundant data. This process is thought to enhance learning, decision-making, and overall cognitive performance.)

 

The researchers suggest that this phenomenon of adaptive forgetting, where memory for dung visited the previous day fades, may be beneficial for horses. It optimizes risk assessment by preventing unnecessary interruptions in foraging caused by conspecifics and ensures that their attention remains focused on current and potentially more relevant environmental cues.

 

 

For more details, see:

 

Audrey EM Guyonnet, Ian Q. Whishaw,

Adaptive forgetting of place/object memory for dung in the domestic horse (Equus ferus caballus): Memory for a day.

Behavioural Processes,

Volume 217,

2024,

105025,

ISSN 0376-6357,

https://doi.org/10.1016/j.beproc.2024.105025

Assessing the impact of blindfolding on equine handling

Blindfolding horses is thought to make them easier to handle in stressful situations. By covering their eyes, blindfolds can reduce distractions that might make them anxious, especially in new or tense environments. However, there has been limited research in this area so far.

A study conducted by Caleigh Copelin, Bryn Hayman, Renée Bergeron, and Katrina Merkies at the University of Guelph investigated this topic. Their research suggests that blindfolding might offer benefits when encountering visually intimidating stimuli, especially in situations where time constraints are not present.

 

However, in emergency situations, such as barn fire evacuations, blindfolding is likely to prolong lead time and exacerbate handling difficulties. This could impede successful rescue efforts and potentially jeopardize the safety of both humans and animals.

 

The study involved thirty-three riding school horses led through a course of obstacles, both blindfolded and unblindfolded. Parameters such as time taken, lead rope pressure, heart rate, and frequency of avoidant or resistant behaviour were recorded and compared between the two groups.

 

Overall, blindfolded horses required more time and exerted greater lead rope pressure when led from a stall compared to unblindfolded horses. They also exhibited higher frequencies of avoidant and refusal behaviours and experienced higher heart rate increases during the process. 

 

However, when navigating a visually frightening obstacle (a gate made of pool noodles that brushed their flanks), blindfolded horses needed less time, exerted less lead rope pressure, and displayed fewer avoidant or refusal behaviours, than they did when not blindfolded.

 

The researchers suggest that blindfolding may be beneficial in situations involving visually frightening stimuli and where time constraints are not a concern. Nevertheless, further research is necessary to evaluate more realistically the effectiveness of blindfolds in simulated emergency scenarios.

 

For more details, see:

 

Copelin, C, Hayman, B, Bergeron, R, Merkies, K,.

Compliance or confusion? The usefulness of blindfolding horses as a handling technique,

Applied Animal Behaviour Science, (2024)

Vol 271,106180,

 

https://doi.org/10.1016/j.applanim.2024.106180

New Morris Animal Foundation research grants

 Morris Animal Foundation announced its selection of 10 new grants dedicated to enhancing the well-being of domesticated horses, ponies, donkeys and mules.

Morris Animal Foundation's mission is to bridge science and resources to advance the health of animals. Founded in 1948 and based in Denver, Colorado, it is one of the largest non-profit animal health research organizations in the world. 

 

Applications were reviewed and rated based on impact and scientific rigour by the Foundation’s scientific advisory boards, which are made up of topic experts in the veterinary community.

 

"We are excited to fund these research proposals that will advance equid health," said Dr. Kathy Tietje, Chief Program Officer at Morris Animal Foundation. "Through these grants, we aim to elevate the quality of life, ensuring a brighter, healthier future for horses, ponies, donkeys and mules."

Research topics being supported include separation-related anxiety in horses, equine metabolic syndrome, and equine protozoal myeloencephalitis.

 

The full list of grants awarded is: 

 

Claire Ricci-Bonot, University of LincoIn, United Kingdom; "An Exploration of the Nature of Separation-Related Problems in the Horse." Researchers will use survey tools to learn more about separation anxiety in horses, including its different forms and situational triggers.

Angela Gaesser, University of Pennsylvania; "What Role Does Epidermal Growth Factor Receptor Pathway Play in the Pathogenesis and Treatment of Equine Osteoarthritis." Researchers will study if a signalling pathway contributes to the progression of osteoarthritis and if a novel treatment targeting this pathway can help affected horses.

Edward J. Knowles, Royal Veterinary College, United Kingdom; "Insights into the Pathogenesis of Equine Metabolic Syndrome: Plasma Amino Acid and Acylcarnitine Profiles in Ponies with Insulin Dysregulation." Researchers will learn more about insulin resistance and laminitis in horses and develop cost-effective tools to monitor these patients better.
 
Serena Ceriotti, Auburn University; "Effect of Omeprazole Treatment on the Pharmacokinetics of Orally Administered Flunixin Meglumine in Adult Horses: A Pilot Study." Researchers will study the anti-ulcer drug omeprazole, often prescribed with the NSAID flunixin meglumine and its impact on the latter drug's ability to reduce pain in horses effectively.
 
Izabela de Assis Rocha, University of Kentucky; "Investigation of the Immunopathogenesis of Equine Protozoal Myeloencephalitis." Researchers will study why a small percentage of horses infected with the causative parasite Sarcocystis neurona are afflicted with a severe neurological disease called equine protozoal myeloencephalitis while other infected horses are unaffected.
 
Sriveny Dangoudoubiyam, Purdue University; "Determining the Role of Dense Granule Protein, SnGRA9, in Sarcocystis neurona Infection." Researchers will study how a protein helps the parasite Sarcocystis neurona grow and reproduce in infected horses.
 
Breanna Sheahan, North Carolina State University; "Identifying CFTR Inhibition as a Treatment for Equine Diarrhea Using an In Vitro Patient-Derived Organoid Platform." Researchers will use an organoid platform, a 3D cell culture, to study a potential new treatment for severe diarrhoea in horses.
 
Kristen Conn, University of Saskatchewan, Canada; "Understanding the Chromatin Regulation of Lytic Equine Herpesvirus 1 (EHV1) Gene Expression." Researchers will work to understand better how EHV1 causes disease and use this information to inform the development of improved treatments.
 
Carrie J. Finno, University of California, Davis; "Unraveling the Genetic Etiology of Equine Neuroaxonal Dystrophy in Quarter Horses and Warmbloods." Researchers will search for causative genes associated with a common neurological disease in horses called equine neuroaxonal dystrophy/degenerative myeloencephalopathy or eNAD/EDM.
 
Thilo Pfau, University of Calgary, Canada; "A Team-Based Approach to Monitoring Gait Symmetry: Hoof Care Providers, Horse Owners and Veterinarians Working Toward Prevention of Lameness." Researchers will partner with hoof care providers, veterinarians and owners to evaluate the feasibility of using video technology to monitor horse gait changes.

 

 

(Edited press release) See:

 

https://www.morrisanimalfoundation.org/article/foundation-announces-grant-recipients-equine-health-studies

Effect of different hay feeders on behaviour

 Horses, being continuous grazers, have a natural inclination to feed steadily. Feral and wild horses may spend about 16 hours per day grazing. 

Allowing domesticated horses free access to roughage aligns with their natural feeding behaviour, representing a potentially optimal approach for horse health and welfare.

However, there are instances where restricting their food intake becomes necessary for management or health reasons. Nevertheless, such restrictions may impact their welfare and behaviour.

 

Implementing tools like hay-nets/bags and slow-feeders may prove helpful in decreasing food waste, extending the time horses spend consuming roughage, and potentially reducing undesirable behaviours.

 

The introduction of automatic hay boxes, providing scheduled feeding times throughout the day, contributes to minimising food waste. Despite this advantage, timed feeding through these devices may lead to abnormal behaviours in horses due to limited access to roughage.

 

A recent study evaluated the impact of three different hay feeders and the availability of roughage on horse behaviours in dry feed lots. The goal was to identify improved feeding techniques that could optimize feeding management, diminish abnormal behaviours, and improve the overall welfare conditions of horses in equine establishments.

 

Fifteen healthy thoroughbred cross horses from the Polo Club at Colorado State University participated in the research, employing a 3x3 Latin square design. The study comprised three groups, each consisting of five horses, with each group undergoing 15 days of one of the three treatments: free choice hay, slow feeder, or box feeder. At the conclusion of each treatment period, the horses underwent weighing, and blood samples were collected to monitor cortisol levels. Behaviour was  monitored throughout the final day of each treatment session.

 

The research, funded by Morris Animal Foundation, is published in Journal of Equine Veterinary Science.

 

Lead author, Jéssica Carvalho Seabra, said “Taking care of horses means more than just giving them a place to stay, food and water. It means giving them an environment where they can do things that are part of their natural behaviour like grazing.”

 

The researchers found that horses using automatic boxes and slow feeders consumed less and exhibited slower weight gain, indicating effective regulation of food intake. 

 

Horses with the freedom to choose when to eat had the highest hay utilization and weight gain rates, suggesting that this approach might not be optimal for overweight horses.

Horses with access to free choice feeding or a slow feeder spent more than half their day doing natural activities such as foraging. 

 

In contrast, horses using box feeders spent only about a quarter of their day eating, leading to increased time spent standing, sniffing the ground, and consuming their own faeces.

Furthermore, horses using the box feeder displayed more signs of aggression. During the study, the researchers noticed that horses became more aggressive as the feeders' size decreased and access to the food became more difficult. To address this issue, researchers recommend ensuring adequate space for each horse to eat without feeling crowded, especially when providing a limited amount of food.

 

"Selecting the right feeding technique can extend the time horses engage in natural behaviours, reducing the incidence of chronic stress and potentially curbing the emergence of abnormal and stereotypic behaviours in the long run," Carvalho Seabra said.

 

For more details, see:

 

Jéssica Carvalho Seabra, Tanja Hess, Marcos Martinez do Vale, Katherinne Maria Spercoski, Ryan Brooks, João Ricardo Dittrich,

Effects of Different Hay Feeders, Availability of Roughage on Abnormal Behaviors and Cortisol Circadian Rhythm in Horses Kept in Dry Lots,

Journal of Equine Veterinary Science (2023) Vol 130, 104911,

https://doi.org/10.1016/j.jevs.2023.104911.

Grants available for behavioural research

 Morris Animal Foundation has announced a fresh call for research proposals with the goal of enhancing the well-being of horses by advancing our understanding of behavioural health and welfare. The Foundation is particularly keen on projects related to cognition, learning, stereotypies, separation anxiety, horses' affiliative behaviour towards humans, the impact of equine temperament on their welfare, and equine psychopharmacology. Please note that proposals solely focused on behavioural measurements for non-behavioural conditions will not be considered. 

This initiative has been made possible thanks to a generous donation from Dr. Wendy Koch, a veterinarian who has been a steadfast supporter of the Foundation for over three decades. Dr. Koch embarked on her career in animal welfare with the federal government back in 1990 and achieved board certification in animal welfare in 2016. Her deep interest in equine behaviour and welfare research prompted her to champion funding in these important areas.

 

Researchers interested in this opportunity should submit their proposals by 4:59 p.m. ET on December 13, 2023. 

 

For details on how to apply, see the Foundation's Grants page at:

 

https://www.morrisanimalfoundation.org/apply

Horses know when you are happy or sad

 

A horse in the experimental set-up, wearing the heart rate monitor belt.
Two video projectors at the back of the testing box project images
onto two screens in front of the horse. Photo: Plotine Jordan

New research shows that horses can distinguish between human expressions of happiness and sadness conveyed through facial movements or vocal tones. The study found that horses were more attracted by facial expressions of happiness than sadness, and they seemed more excited by the happy voices. 

Emotions are a part of how people interact and talk to each other, and they could also play a role when we interact with other species. 

 

Many types of animals, as diverse as orangutans and pigeons, are known to sense human emotions. Recently, studies on domestic animals such as dogs, cats, horses, and goats have shown they can recognize various human emotions shown on our faces. However, this area of research has mainly focused on two emotions: joy and anger. What about other emotions, such as sadness?

 

The study, conducted by an international research team from the National Research Institute for Agriculture, Food and Environment (INRAE) in France, the University of Tours in France and the University of Turku in Finland, observed and analysed horses’ behaviour when presented with human faces and voices expressing joy or sadness. The heart rate of the horses was also recorded during the experiment.

 

“Sadness is a particularly interesting emotion, because it is not only of negative valence – contrary to joy, which is positive – but it is also of low arousal. Previous studies have shown that horses react to high-arousal emotions like anger or joy. Could they also detect signals of sadness, a low-arousal emotion? We wanted to study whether horses can associate the vocal and facial signals of human sadness, as they can for joy and anger,” says the lead author of the study, Doctoral Researcher Plotine Jardat from the French National Institute for Agriculture, Food and the Environment and the University of Tours, France.

 

During the study, horses faced two screens. One showed a video of a person looking happy, while the other showed the same person looking sad. At the same time, a voice played, either sounding happy or sad.

 

The horses’ first look indicated they matched the face and voice expressing sadness or happiness. The researchers noticed that when the horses first saw the pictures, more of them spent longer looking at the picture that didn't match the sound, compared to the one that did match.

 

So, when the horses looked at the pictures for the first time, they were surprised when a sad face was paired with a happy voice, and the other way around. The researchers suggest this implies that horses can link a human face and voice showing the same emotion, whether it's sadness or happiness.

 

“This is interesting because it would mean that when horses observe our faces and hear our voices, they don’t just see and hear separate things, but they are able to match them across different modalities. You could imagine that they have a particular box in their mind labelled ‘human sadness’ containing the characteristics of both a human sad face and a human sad voice,” says Doctoral Researcher Océane Liehrmann from the University of Turku.

A similar setup has been used in several previous experiments by the team. Its purpose is to explore the animals’ mental processing of the images and sounds and their congruence. In the previous experiments on anger and joy as well as on the perception of adults and children, the horses reacted to the setup by looking more at the image that did not match the sound. The researchers believe that horses look more at the incongruent image because they are intrigued by the lack of correspondence between this image and what they hear.

 

After the first glance, the researchers saw that horses paid more attention to the screen displaying the happy face. They looked at it more often and for a longer time. Also, the horses’ heart rates went up more when they heard the happy voice compared to the sad one. This indicates that the horses were more alert and excited when the voice was joyful.

 

The researchers suggest three possible explanations for these findings. First, the horses might have been more interested in the happy images due to their movement, and more excited by the joyful voices because of the way they sounded, like changes in pitch. Second, the horses could have connected human happy faces with positive situations, making them want to look at these expressions that remind them of good memories. Third, the horses might have felt more positive when looking at the happy pictures and more stimulated when hearing joyful voices due to something called "emotional contagion." This is when the emotions of an observer match the emotions of the one they're observing. It has been seen in humans and primates, and studies suggest it could also happen between humans and other animals, like horses. This phenomenon is often seen as a basis for empathy.

 

“Overall, our study shows that horses can differentiate audible and visual signals of human joy and sadness, and associate the corresponding vocal and facial expressions. Horses were also more attracted and seemed more animated by joyful expressions, so people who interact with horses could benefit from expressing joy during these interactions,” Plotine Jardat concludes.

 

The researchers point out that further studies are needed to better understand horses’ perception of human sadness. In the future, they aim to find out, for example, whether horses can also differentiate sadness from other negative emotions, or whether sad expressions from humans can influence horses’ behaviour, especially during human-horse interactions.

For more details, see:

Horses discriminate between human facial and vocal expressions of sadness and joy. 

Plotine Jardat, Océane Liehrmann, Fabrice Reigner, Céline Parias, Ludovic Calandreau & Léa Lansade 

Anim Cogn (2023) 26, 1733–1742 

https://doi.org/10.1007/s10071-023-01817-7

New research projects receive funding

 Morris Animal Foundation has provided funding for seven new research projects focused on
equine health. These studies aim to address various equine health issues, including contagious upper respiratory disease, and sepsis in foals. 

The research initiatives receiving support are as follows:

 

• Impact of cyproheptadine on blood variables and clinical signs of Pituitary Pars Intermedia Dysfunction (PPID) in Horses. (Dr. Nicholas Frank, Mississippi State University) 

• Development of an effective intramuscular vaccine against strangles, based on the "S" protein of Streptococcus equi subspecies equi (SEE). (Dr. Noah Cohen, Texas A&M University.)

• A novel diagnostic test for Equine Pituitary Pars Intermedia Dysfunction (PPID).( Dr. Dianne McFarlane, University of Florida )

• Increasing understanding of foal sepsis and potential new treatment options (Dr. Katarzyna Dembek, North Carolina State University)

• Examination of a faecal-based test to aid in the diagnosis of gastric ulcers in horses (Dr. Canaan M. Whitfield-Cargile, University of Georgia)

• A study of remote behavioural and physiologic monitoring to assess changes in equine discomfort behaviours and their association with epidural morphine administration. (Dr. Hope Douglas, University of Pennsylvania)

• Investigation into drugs targeting the non-structural protein 4 of African Horse Sickness (Dr. Constantinos Kurt Wibmer, University of the Witwatersrand, South Africa )

 

Dr. Kathy Tietje, Chief Program Officer at Morris Animal Foundation, expressed excitement about supporting these projects, which aim to advance equine health and welfare through innovative research. The studies are scheduled to commence in the current year, contributing valuable insights to improve equid health and well-being.

For more about Morris Animal Foundation, see:

 morrisanimalfoundation.org

Why do horseflies avoid stripes?

 

(c) Martin How

Researchers at the University of Bristol have discovered the reason why horseflies tend to avoid attacking individuals with stripes, as opposed to those with big, solid dark patches. 

Their findings show that stark black-and-white contrasts and small dark patches are particularly
effective in preventing horsefly attack. Specifically, these features eliminate the outline of large, single-colour dark patches, which horseflies find attractive at close range. 

 

The team suggest that the thin back stripes serve to minimise the size of local features on a zebra that are appealing to the biting flies.

 

The research was led by Professor Tim Caro and Dr Martin How both from the University of Bristol’s School of Biological Sciences. An open access report of the work is published in the Journal of Experimental Biology.

 

 Prof Caro explained: “We knew that horseflies are averse to landing on striped objects - a number of studies have now shown this, but it is not clear which aspects of stripes they find aversive.

 

“Is it the thinness of the stripes? The contrast of black and white? The polarized signal that can be given off objects? So, we set out to explore these issues using different patterned cloths draped over horses and filmed incoming horseflies.”

 

The team found that tabanid horseflies are attracted to large dark objects in their environment but less so to dark broken patterns. All-grey coats were associated with by far the most landings, followed by coats with large black triangles placed in different positions, then small checkerboard patterns in no particular order. In another experiment, they found contrasting stripes attracted few flies whereas more homogeneous stripes were more attractive.

 

Professor Caro added: “This suggests that any hoofed animal that reduces its overall dark outline against the sky will benefit in terms of reduced ectoparasite attack.”

 

The team found little evidence for other issues that they tested, namely polarization or optical illusions confusing accurate landings such as the so-called ‘wagon-wheel effect’ or ‘the barber-pole effect’.

 

They conclude: “Our working hypothesis now is that horseflies are attracted to equid hosts owing to a combination of odour at a distance, then size of the animal contrasted against the sky or vegetation at a middle distance. But at close range, where they can no longer see the body's outline, flies make a visual switch to local features. If these are small dark objects contrasted against a light or white background, the horsefly no longer recognizes this as a host target and veers away. The contrast of stripes and their relatively small size are therefore the key elements of how stripes operate to thwart fly landings.”

 

Now the team want to determine why natural selection has led to striping in equids - the horse family - but not other hoofed animals.

Professor Caro added: “We know that zebra pelage – fur - is short, enabling horsefly mouthparts to reach the skin and blood capillaries below, which may make them particularly susceptible to fly annoyance, but more important, perhaps, is that the diseases that they carry are fatal to the horse family but less so to ungulates. This needs investigation.”

 

For more details, see:

 

Why don't horseflies land on zebras?

Tim Caro, Eva Fogg, Tamasin Stephens-Collins, Matteo Santon, Martin J. How

J Exp Biol (2023) 226 (4): jeb244778.

https://doi.org/10.1242/jeb.244778