Research indicates that horses can experience depression. Here we’ll review the pioneering study that sought to identify depression in horses and examine some of the causes, list the signs to watch for and give tips on how to help alleviate depressive symptoms in affected horses.
The study
A French study evaluated domestic horses for signs of depression by comparing their behaviour to that exhibited during depressive states in humans. For six months, researchers observed the spontaneous behaviour of 59 working horses in their home environments.
The horses involved in the study were a mix of breeds and sexes and came from three separate riding schools. All horses had similar types of stabling, feed and work parameters.
The study evaluated the horses’ posture, responsiveness to their environment, and levels of anxiety and measured the amounts of cortisol, a stress hormone, in their blood.
Researchers recorded all behaviours, giving special attention to immobile moments in which they recognised a particular posture, termed a ‘withdrawn’ posture, as distinctly different from other typical stances. Horses exhibiting the unusual ‘withdrawn’ posture stood immobile, with open eyes, stretched necks (open jaw-neck angle), and the neck at about the same level as the back. The stance differs from that of a horse observant of his surroundings, whose neck is held higher and ears move around in response to environmental stimuli. It also differs from the posture of a resting horse, who relaxes his muscles, often rests one hind leg, rotates his ears laterally, allows eyelids and lips to droop, and often holds his neck such that it slopes lower.
Compared to ‘non-withdrawn’ horses from the same stable, the withdrawn horses in the study appeared more indifferent and unresponsive to stimuli in their home environment yet reacted more emotionally to challenging or novel situations.
These characteristics are similar to aspects of depressive states in humans and other animals. Twenty-four per cent of the 59 horses in the study presented, at least once, the withdrawn posture of the stretched neck, dull open-eyed gaze, and immobile head and ears, up to four times each in 30 minutes. Mares were over-represented in the findings, with one-third of mares in the study presenting this depressive appearance and lack of response to external stimuli.
Whilst not conclusive, the study reiterates other research findings and anecdotal evidence that some horses experience depressive states akin to those seen in humans. Whether or not the experience of depression is similar in horses to humans requires investigation. Still, this study provides a good starting point for looking at depressive type behaviours in horses and finding ways to improve this mental state in the equine.
Causes of depression
Unfortunately for domestic horses, many factors are known to lead to chronic stress, and it is postulated that, as is the case with humans, long-term exposure to these inescapable or repeated stressors can precipitate depression. By this token, any of the following circumstances, or a combination of them, may be at the root of a horse’s stress and subsequent depression:
- Pain: Pain is an extremely common stressor for the horse. It can dramatically affect a horse’s emotional state, just as it does a human. Further, pain may have the additional stressful effect of leading to the need for box rest. This restriction keeps horses from exercising, socialising, and grazing as usual, leading to further stress.
- Social isolation: Social isolation is one of the leading causes of stress in social animals. A horse living alone, isolated or stabled for long periods is likely to become chronically stressed and therefore highly susceptible to stress-related illnesses and depression.
- Confinement: Horses have evolved to travel long distances every day, so it’s highly unnatural for them to be confined in a small area, unable to move about and graze. Therefore, it is no coincidence that when stabled for long periods, horses may start performing stereotypical behaviours like windsucking, weaving, or box walking to cope with the frustration of being unable to move freely.
- Boredom: Horses are intelligent creatures that need mental stimulation. Those stalled for long periods with nothing to do or allowed little or no exercise can become very bored. This boredom can then lead to the development of a range of behavioural issues.
- Feeding practices: Horses have evolved to ‘trickle feed’, grazing as they roam for up to 18 hours per day. This means three large concentrate meals per day and one small hay net overnight is not an adequate feeding regime, as it can leave horses hungry, stressed, and at risk of developing gastric ulcers.
- Stressed handlers or other horses: The emotional state of surrounding people and equines can adversely affect a horse. For example, if one horse in a group is overly tense, it can lead to problems within the herd and cause tension among other group members. Similarly, a tense handler can elicit anxiety in the equine.
- Unpredictability: It is essential for horses, as prey animals, to feel safe. If their environment changes all the time, they may never feel safe enough to relax completely. For example, new stables, new horses coming and going, unexpected noise, changes to schedules, varying handlers and inconsistent training techniques can all leave horses anxious. This unpredictability can also affect sleep amount and quality, and sleep deprivation is another contributor to stress and generally poor health.
- Harsh training methodologies: Intense or overly prolonged exercise sessions (whether in training or competition) can cause physical stress. Punishment and physical restraints, e.g. side reins applied tightly, also put enormous strain on horses mentally and physically. Harsh training methods make horses fearful of trainers and their environment, which leads to stress. Basically, any excessive, restrictive or unpredictable demands placed on a horse can cause stress and thus elicit depressive behaviours.
Signs to look for
Depression in the horse is thought to be demonstrated by:
- A ‘withdrawn’ stance with a dull stare, immobile head and ears.
- A lack of interest in the environment – may even stand with his head towards the stable wall.
- Reduced reactions to environmental stimuli, including handlers, yet increased reactiveness to new stimuli.
- Stereotypies like cribbing, weaving or box walking.
- Unpredictable behaviours.
- Increased fear, anxiety or spookiness.
- Long periods of immobility.
- Unwillingness to work.
- Avoidance of other horses.
- Signs of sleep deprivation.
- Decreased appetite/changes in weight.
- Poor muscle development.
- Increased susceptibility to infection.
If you spot any of these changes in your horse’s attitude or behaviour, you should schedule a veterinary check-up to rule out any physical problems. This is first and foremost to check for signs of physical illness that might be precipitating the behaviour, but secondly to examine for gastric ulcers or other signs that might have occurred secondary to the stress and depression. You’ll be amazed at how quickly these issues can develop in a stressed animal!
Once physical issues are ruled out or under control, you can start to work to alleviate the depressive state.
Options to alleviate depression
If your horse is depressed, simple management changes to reduce his stress and/or boredom can substantially improve his outlook on life. Approach changing his lifestyle to enable him to lead a more natural life while also keeping some healthy routines in place.
Firstly, providing more turnout time will do wonders for depression. You need to make sure that your horse has companions that he enjoys spending time with and that he can access resources such as additional grass and water when in the paddock.
Then 24/7 access to forage is an absolute must. This allows your horse to practice his natural trickle feeding behaviours, which will increase his sense of wellbeing.
Any way you can enrich his environment will also be very appreciated. This may involve toys in the stable, increasing access to companions or even putting a companion animal in his stable.
Finally, assess your riding and training programme. Does it expose your horse to harsh methods such as long sessions, unpredictable demands, unrealistic expectations or environmental challenges such as extreme heat? Any of these factors – or a combination of them – can discourage him, making him averse to performing or even being handled. Similarly, you need to consider whether or not your horse can perform the tasks you are asking of him. Overfacing a horse or making physical demands that he continually struggles to meet can result in sore muscles and mental shutdown.
Take-home message
Depression in horses seems to be an unfortunate consequence of many of the effects of domestication. The more we can try to ‘naturalise’ our horse’s experience within the domestic context, the happier the horse is likely to be. Small changes can make a big difference, so think about things from your horse’s perspective and see what you can do to improve his sense of wellbeing.