We know humans experience depression, considered a major mood disorder, but do horses? Yes, evidence indicates that they can experience and suffer from depression. Domestic horses may live in a state of chronic stress, depending on their physical health, living arrangements, social interactions, type and duration of work, training methods used on them, and even their feeding schedule.
Here, we’ll review the pioneering study that identified depression in horses. We’ll examine some of the causes, list signs to watch for, and give tips on how to help alleviate equine depression.
Study Finds Evidence
A study in France evaluated domestic horses for signs of depression by comparing their behavior to that exhibited during depressive states in humans. For six months, researchers observed the spontaneous behavior of 59 working horses in their home environment, focusing on bouts of immobility in which the horses displayed atypical posture.
The study also evaluated the horses’ responsiveness to their environment and their levels of anxiety, plus measured the amounts of the stress hormone cortisol in their blood.
A mix of breeds and sexes, the horses were from three riding schools; all had the same type of stabling, feed, and work parameters. The study focused on two elements—the spontaneous expression of “behavioral despair” and unresponsiveness to a variety of environmental stimuli (tactile/visual, human/non-human).
Researchers recorded all behaviors, giving special attention to immobile moments in which they recognized a particular posture, termed “withdrawn,” as distinctly different from other typical stances.
Horses exhibiting the unusual “withdrawn” posture stood immobile, with open eyes, stretched necks (open jaw-neck angle), and with the neck at about the same level as the back. That posture differs from that of a horse observant of his surroundings, whose neck is held higher and whose ears move inquisitively.
It also differs from the posture of a resting horse, who relaxes his muscles, often cocks/relaxes one hind leg, rotates ears laterally, allows eyelids and lips to droop, and holds his neck such that it slopes lower and rounder.
A depressed horse’s open-eyed, dull, unfocused gaze and immobile head and ears suggest “behavioral despair.” Compared to “non-withdrawn” horses from the same stable, the withdrawn horses in the study appeared more indifferent and unresponsive to stimuli in their home environment, yet reacted more emotionally to challenging situations.
All these characteristics are similar to some aspects of depressive states in humans and other animals.
Twenty-four percent of the 59 horses in the study presented, at least once, the withdrawn posture of 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 syndrome.
Causes of Depression
Unfortunately for domestic horses, many factors can lead to chronic stress, and long-term exposure to inescapable or repeated stressors can lead to depression. Any of the following circumstances, or a combination of them, may be at the root of a horse’s stress and subsequent depression.
[RELATED: EFFECTS OF SOCIAL STRESS]
• Pain. An extremely common stressor, pain can dramatically affect a horse’s emotional state. It may also have a carry-over effect, as it can lead to the imposition of stall rest. This restriction keeps horses from exercising, socializing, and grazing—which can then lead to further stress.
• Social isolation. According to Prof. Robert Sapolsky, a neuroscientist at Stanford University, one of the leading causes of stress to social animals (like horses) is social isolation. 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 up to 100 miles a day, so it’s unnatural for them to be confined in a small area, unable to move about and graze. Thus it’s no coincidence that when stabled for long periods, they may start performing stereotypic behaviors like windsucking or weaving in an attempt to cope with the frustration of being unable to move freely.
• Harsh training. Intense and/or overly prolonged exercise (whether in training or competition) can cause physical stress. Punishment and physical restraints also put enormous strain on horses both mentally and physically. Harsh or coercive training methods make horses fearful of trainers and their environment, which leads to stress
• Transport. Several studies have shown that being transported can even increase the risk of colic. In addition to being confined and unable to move, trailered horses may be exposed to extra-cramped spaces, excess heat/cold, poor ventilation, slippery floors, and poor drivers.
• Boredom. Horses are intelligent creatures that need mental stimulation. Bored horses easily become frustrated and stressed. Those stalled for long periods with nothing to do, or kept in a flat, boring paddock, or allowed little or no exercise can become stressed and depressed, potentially developing a range of behavioral issues.
• Unpredictability. It’s important for horses, as prey animals, to feel safe; if their environment changes continuously, they may never feel safe enough to completely relax. For example, unfamiliar stables, new horses coming and going, unexpected noise, changes to feeding schedules, varying handlers, and inconsistent training techniques can all leave horses restless and anxious as to what may happen next.
• 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 or aggressive, it can lead to problems within the herd and cause tension among other members of the group.
• Feeding. Horses have evolved to “trickle feed,” grazing as they roam for up to 18 hours a day. That means three large grain meals a day and one small hay net overnight is not an adequate feeding regimen, as it can leave horses hungry, stressed, and at risk of developing gastric ulcers.
Signs to Look For
You can spot depression in a horse if you look for the signs from the study described earlier: a level-neck “withdrawn” stance, dull stare, immobile head and ears, and reduced reactions to humans yet increased reactiveness to new stimuli.
A withdrawn horse, uninterested in his environment, may also stand with his head toward the wall of his stall.
Other potential signs to watch for include:
• Stereotypies like cribbing or weaving.
• Unpredictable behaviors.
• Long periods of immobility.
• Decreased appetite/changes in weight.
• Unwillingness to work.
• Lack of sleep.
• Increased susceptibility to infection.
• Poor muscle development.
• Increased fear, anxiety, or spookiness.
• Avoiding other horses.
If you spot any alarming changes in your horse’s attitude or behavior, schedule a thorough veterinary checkup to rule out physical problems. Horses are highly susceptible to a range of physical issues if their depression goes untreated and may develop gastric ulcers or colic if stressed even for only a short period of time.
[RELATED: HORSE GUT HEALTH]
Options to Alleviate Depression in Horses
If your horse is depressed, simple changes in management to reduce his stress and/or boredom can substantially improve his outlook on life. Approach changing his lifestyle with the mindset of enabling him to lead a more natural life while also keeping to some firm routines.
If your horse now lives alone, provide him with a stable or pasture companion. If you can’t afford to keep another horse, perhaps arrange for a horse belonging to someone else to live with your horse. If you can’t take on another horse, then a donkey, goat, or other barnyard animal can help keep your horse company.
If, on the other hand, your horse shows signs of stress because of an aggressive companion that prevents him from relaxing or eating, take all necessary steps to separate them enough that your horse feels safe.
Providing turnout or increasing your horse’s turnout time will also do wonders for depression. Analyze what it’ll take to make this change-—you may have to adjust your schedule, pay an employee, swap favors with a friend, or even move to another stable that offers turnout. This is such a critical component in a horse’s life that it should be a top priority.
Access to forage at all times also goes a long way toward improving a horse’s emotional state. If he can’t be out on pasture all the time, adjust your feeding regimen (perhaps with slow-feed nets) so that he can be nibbling throughout the day, as nature intended. Any way you can enrich his environment and extend his “chew time” may improve his mood.
Finally, assess your riding and training program. Does it expose your horse to harsh methods, excessively long sessions, unrealistic expectations, or environmental challenges such as extreme heat or bad footing? Any of those factors—or combination of them—can discourage him, making him averse to performing or even being handled.