The mental challenges of being a horse in the modern age


stock-foal-feed-rear_5898Scientists have again highlighted the mental challenges of being an equine in the modern age, with a study indicating horses can suffer a depressive-like state.

Their findings add to a growing body of evidence that suggests horses face the same issues that challenge people in their everyday lives.

The study team from the University of Rennes 1 in France and Canada’s University of Guelph said some captive and domestic animals responded to confinement by becoming inactive and unresponsive to external stimuli.

Inactivity was one of the behavioural signs of clinical depression in humans, they noted, the symptoms of which can include a deficit in selective attention.

Some riding horses displayed “withdrawn” states of inactivity and low responsiveness to stimuli that resembled the reduced engagement with their environment found in some depressed patients, the researchers wrote in the journal, Behavioural Processes.

Céline Rochais, Séverine Henry, Carole Fureixc and Martine Hausberger hypothesized that withdrawn horses experienced a depressive-like state. They set out to evaluate their level of attention by testing them with novel sounds.

Five unfamiliar sounds were broadcast to 27 horses, 12 of whom had been assessed as being withdrawn, over the course of five days. The sounds included calls made by baboons, whales and geese.

The horses’ reactions and the time spend being attentive to the sounds were recorded.

Non-withdrawn horses reacted more and their attention lasted longer than that of withdrawn horses on the first day, but the duration of their attention tended to decrease over the days. However, those of withdrawn horses remained stable.

“These results suggest that the withdrawn horses’ selective attention is altered, adding to already evidenced common features between the horses’ state and human depression,” they wrote.

Researchers from the University of Rennes 1 have delivered several major studies in recent years that have explored elements of depression in horses.

In 2012, a study suggested horses might be a useful model for studying animal depression and provide insights into the human condition.

Fureix, Hausberger, Henry, Patrick Jego and Léa Lansade observed the spontaneous behaviour of 59 French riding-school horses in their home environment.

The researchers spotted individual horses displaying a particular behavioural and postural profile that had strong similarities with a “depressive syndrome”, they reported in the open-access journal, PLOS ONE.

depressionThey focused on what they called immobility bouts of apparent unresponsiveness, in which the horses demonstrated a withdrawn posture. The researchers evaluated the horses’ responsiveness to their environment and their anxiety levels, and analysed plasma cortisol levels – a key indicator of stress.

Twenty-four per cent of the horses showed the withdrawn posture, characterized by a similar height between the horse’s neck and back and a stretched neck. The horses also had a fixed gaze with head and ears fixed – a profile that suggested a spontaneous expression of “behavioural despair”, the researchers said.

“This posture is distinguished from postures associated with observation of the environment (for which the neck is higher), and resting, when eyes are at least partly closed and the horse’s neck is rounder. Special attention was paid to eye and ear position.”

The animals’ responsiveness to touch was also tested. Withdrawn horses were found to be less responsive.

Other unusual features of “withdrawn” horses were the absence of ear and head movements, and a fixed gaze.

In all, 24 per cent of the 59 horses from the riding school were observed displaying the withdrawn posture at least once (standing with eyes open, a stretched neck, and with a similar height between neck and back). Some displayed it up to four times each in 30 minutes.

Withdrawn horses also tended to show higher reactions when confronted with a novel object.

When compared with “non-withdrawn” horses from the same stable, withdrawn horses appeared more indifferent to environmental stimuli but reacted more emotionally in more challenging situations. They exhibited lower plasma cortisol levels.

Females were over-represented among the withdrawn horses.

The researchers saw parallels with the everyday lives of people.

“Domestic horses encounter chronic stress, including potential stress at work, which can induce behavioural disorders,” they wrote.

Domestic horses, for example, may face social and space restriction in their daily lives. They may have to work on a daily basis and have ‘interpersonal’ interactions with a human “boss” who manages or rides them.

“As for human depression, horse ‘depression’ corresponds to a multifaceted syndrome: apathy and loss of interest, lower reactivity but higher anxiety.

“These horses surprisingly displayed higher emotional responses when facing a challenging situation, suggesting, as in depressive humans, a higher level of anxiety.”

They said that horses’ depressive states may reflect genetic inputs – as one breed, the French Saddlebred, was over-represented in the sample – and environmental factors certainly had an effect.

stock-eye_1561The prevalence of females displaying this syndrome was another intriguing convergence with humans, they noted.

“These results open a promising line of investigation of what impaired welfare states could look like in horses.”

They noted that while considerable attention had been paid to vices, little interest had been placed on chronic states where horses “switch off”, becoming unresponsive and apathetic.

They noted: “It has been recently suggested that negative experiences linked to training may add to the effects of management style … and lead to behavioural despair in horses.”

Aspects of this had earlier been investigated by a University of Rennes team. Their study indicated that dressage and high-school work created higher levels of stress in horses than the likes of jumping, eventing and vaulting.

The researchers said it was well known that stress at work could cause negative effects in people, such as anxiety and depression, but could the daily work to which many horses were exposed result in similar effects?

Their findings, published in PLOS ONE, indicated that horses, like people, faced stresses in their daily life involving troublesome human bosses, difficult interpersonal relationships, undue negative reinforcement and poor rewards.

Such negative experiences linked to training could lead horses to switch off, becoming unresponsive and apathetic – the equine equivalent of work-related burnout in people.

The researchers, led by Hausberger, studied 76 French Saddlebred horses stabled at the Ecole Nationale d’Equitation in Saumur.

The horses, aged six to 15, were all geldings and housed in the same conditions, spending 23 hours a day in their stables. They received the same diet. The only difference was in the kind of discipline they performed each day for an hour.

Better understanding of horse behaviour could reduce accident rates, experts believe.

The scientists monitored the horses in their stables for behaviours called stereotypies – abnormal repetitive behaviours which serve no useful function. These include repetitive mouth movement, head tossing or nodding, windsucking, cribbing and weaving.

Abnormal repetitive behaviours in horses are thought to be a way for animals to cope with an unfavourable stress-inducing environment.

They found that the type of work performed by the horses each day had a significant influence on the prevalence and types of undesirable traits shown.

“To our knowledge, this is the first evidence of potential effects of work stressors on the emergence of abnormal behaviours in an animal species,” they reported in their 2009 study.

“It raises an important line of thought on the chronic impact of the work situation on the daily life of individual [horses].”

The researchers found that 65 of the 76 subjects performed some type of stereotypy.

The horses were categorised as doing one of three kinds of work:

  • Jumping/eventing/advanced-riding-school.
  • Dressage/high-school.
  • Vaulting.

“Vaulting horses appeared to be the least prone to stereotypies and performed relatively ‘mild types’ such as tongue play, whereas dressage/high-school horses presented the highest incidence of stereotypies … several of these horses performed two or more types of stereotypies.

“They also performed the ‘more serious’ stereotypies – cribbing, windsucking, head shaking.”

Why should horses get stressed? It could well come down to the humdrum of a workaday life – and trouble with the boss.

“Work sessions are based on training, using more often negative reinforcement or punishment than positive reinforcement.

Depression in horses“Physical and emotional constraints depend also on the type of work performed. Negative consequences of some practices, leading to physical and behavioural resistances, open conflicts and tensions during the work sessions ….

“Conflicting signals given by the rider … may lead the horse to frustration and neurosis.”

Few studies had questioned the possible durable effects of such work stressors – interpersonal conflicts, suppressed emotions, physical constraints – on the daily life of horses outside the work sessions, Hausberger and her colleagues wrote.

Negative experiences linked to training could lead to chronic states where horses switched off, becoming unresponsive and apathetic – states described in humans as work-related burnout.

The authors pondered why dressage appeared to cause the most stress.

“Dressage and high school both expect horses to restrain from expressing emotions and put a strong physical constraint on the movements,” they noted.

“Moreover, cases where orders can be conflictual are more frequent here as the restricted gaits are often obtained by refraining movement through the reins and bit while pushing forward the horse through the legs.

“Therefore both physical and interactional stress can explain the high prevalence and types of stereotypies observed in these horses.”

The researchers said that although some work stressors for horses may be specific to equine work, others were clearly shared with other species, including humans: emotions suppression, interpersonal conflict, physical demands, lack of reward, and negative future expectancy. All are associated with depression in humans.

The authors acknowledged that other factors can be involved in development of stereotypies, including roughage availability, diet, social deprivation, lack of exercise and genetic susceptibilities. The length of time spent in stalls may also have an influence.

However, the results clearly showed that the discipline being performed by the horse influenced the degree to which they showed undesirable traits.

Hausberger also led research that looked for links between the type of work undertaken by a horse and its personality.

The researchers subjected more than 100 adult horses with different careers to standardised behavourial tests.

They found that dressage and high-school horses showed higher levels of anxiousness than those taking part in other disciplines, confirming earlier research indicating that dressage horses were the stress bunnies of the equine world.

These findings also have implications for people. It suggests that the type of work people do may be an important factor in the development of their personalities.

arena-stock-featuredThe horse study was able to eliminate many of the environmental factors that could cloud research into humans.

The horses used for the study were all geldings who lived at the Ecole Nationale d’Equitation and lived under the same conditions.

Hausberger and her colleagues said each horse’s type of work had been decided by the riding school’s stall managers, mostly on their jumping abilities.

However, she noted that an unconscious choice based on individual behavioural characteristics of each horse could not be totally excluded in the findings.

The researchers found that the horses from different types of work differed not so much in their overall emotional levels as in the ways they expressed emotions.

Dressage horses showed “the highest excitation components”, while vaulting horses were the quietest.

The study team said it has been repeatedly hypothesised that job characteristics were related to changes in personality in humans, but often personality models omitted the effects of life experience.

“Demonstrating reciprocal relationships between personality and work remains a challenge though, as in humans, many other influential factors may interfere,” they noted.

The study, published in PLOS ONE, investigated the relationship by comparing the emotional reactivity of horses that differed only by their type of work.

“Horses are remarkable animal models to investigate this question as they share with humans working activities and their potential difficulties, such as ‘interpersonal’ conflicts or ‘suppressed emotions’,” they wrote.

“Clearly, if work characteristics can induce chronic behavioural problems in horses, it could also affect their personality, as it does in humans.”

In all, 119 horses were tested – 89 French Saddlebreds and 30 Anglo-arabs. They were divided into six groups according to the type of work they did, ranging from eventing, to showjumping, dressage, high school, and vaulting.

All had been working in their discipline for at least a year. Hausberger and her colleagues said the tests undertaken on the horses were commonly used to assess emotionality and learning abilities in equines.

They said their findings were, to their knowledge, the first evidence of a clear relationship between type of work and personality in a context where type of work was the only factor that varied.

“Our results support reports suggesting that type of work may be an important factor in the development of humans’ personalities.”

Investigating attentional processes in depressive-like domestic horses (Equus caballus)
C. Rochaisa, S. Henry, C. Fureix, M. Hausberger.
The abstract can be read here.

Fureix C, Jego P, Henry S, Lansade L, Hausberger M (2012) Towards an Ethological Animal Model of Depression? A Study on Horses. PLOS ONE 7(6): e39280. doi:10.1371/journal.pone.0039280
The full study, published under a Creative Commons License, can be read here.

Hausberger M, Gautier E, Biquand V, Lunel C, Jégo P (2009) Could Work Be a Source of Behavioural Disorders? A Study in Horses. PLOS ONE 4(10): e7625. doi:10.1371/journal.pone.0007625
The full study, published under a Creative Commons License, can be read here.

Hausberger M, Gautier E, Biquand V, Lunel C, Jégo P (2009) Could Work Be a Source of Behavioural Disorders? A Study in Horses. PLoS ONE 4(10): e7625.
The full study, published under a Creative Commons License, can be read here.

Hausberger M, Muller C, Lunel C (2011) Does Work Affect Personality? A Study in Horses. PLoS ONE 6(2): e14659. doi:10.1371/journal.pone.0014659
The full study, published under a Creative Commons License, can be read here.

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