Stress and stereotypic behaviour

What stress is

The British Horse Society describes equine stress as a horse trying to cope with something undesirable in its environment or management that is harming its emotional health. Some stress is useful: it protects a horse from danger and helps it learn and adapt. Too much harms its health and wellbeing.

• Acute stress comes from short-term stressors, such as a plastic bag blowing in the wind that makes a horse spook.
• Chronic stress comes from long-term stressors, such as being confined to a stable or living with pain for a long time.

The fight-or-flight response is useful in the short term, to get a horse away from something unpleasant. But when the stressor is repeated or always there, the stress hormones cortisol and adrenaline can leave the horse feeling permanently stressed, and it needs an outlet for that feeling.

Two ways of coping

The British Horse Society describes two coping styles, which horses may use alone or together:

• Active (proactive) copers try to take control, for example by moving away or running off. Their stress is usually easy to see.
• Passive (reactive) copers freeze or become withdrawn. They can look calm and relaxed when they are actually unresponsive and emotionally shut down, and they may be as stressed as an active coper, or even more so.

This is one reason a quiet horse isn't necessarily a happy one. See Reading your horse for the signs.

Common causes of stress

As prey animals, horses are stoic and may show no outward signs of stress. The British Horse Society lists these common sources:

• Travelling: poor driving, an uncomfortable temperature, confinement, unsuitable flooring or being separated from other horses.
• Exercise and competing: discomfort the horse links with being ridden, harsh training methods, or demands beyond its fitness.
• Isolation from other horses or a friend for a long time, such as on box rest.
• Illness or injury: both the pain itself and the vet visits or hospital stay.
• Extremes of temperature. The British Horse Society says a horse's metabolism stays steady between about 5 °C and 20 °C. Outside that range, the horse has to work harder to warm itself up or to cool down by sweating.
• Poor handling: if a horse is repeatedly frightened or handled forcefully, it will expect the same thing in similar situations.
• Clipping, which some horses find very frightening.
• Boredom: horses that can't behave naturally can easily become frustrated.

Stressors can also stack up. The British Horse Society gives the example of a horse with a painful wound, an anxious owner and an unfamiliar vet trying to clean the wound. Each might be manageable on its own, but together they can overload the horse until it reacts.

Stereotypic behaviours

Stereotypic behaviours, or stereotypies, are repetitive behaviours with no obvious goal or function. They are rarely seen in wild animals and mostly found in domestic and captive ones. World Horse Welfare explains that they develop when a horse's basic behavioural needs aren't met or it suffers long-term physical or emotional stress. They become coping mechanisms, which the horse then uses whenever it is stressed. They used to be called "vices", but they aren't bad habits or bad behaviour.

Not every repeated behaviour is a stereotypy. A horse that kicks the stable door at feed time is doing something learnt and goal-directed: it is trying to hurry its feed along.

Why they develop

• Restricted lives. Modern management limits natural behaviours such as foraging, free movement, mutual grooming and life in a herd. World Horse Welfare names restricted turnout, limited social contact, too little forage and too little chewing time as possible causes. Locomotor stereotypies such as weaving and box walking are common where movement is restricted, as in a stable.
• Early life. Many stereotypies are established in the first nine months of life. Foals stabled through weaning and kept apart from other young horses are much more likely to develop one than foals weaned in a herd. Foals whose forage is restricted after weaning are at greater risk of crib biting.
• Diet and pain. World Horse Welfare links crib biting with stressful weaning, diets high in sugar and starch, and restrictive management. Physical stresses such as gastric ulcers can also play a part.
• Brain chemistry. These behaviours are linked to changes in brain chemistry and the release of hormones such as dopamine, which is one reason they are hard to stop once established.

A stereotypy doesn't always reflect a horse's current home. It may have started somewhere that didn't meet the horse's needs and become a habit that continues even after the horse moves somewhere better.

Can horses copy them?

The British Horse Society says there is no evidence that a horse develops a stereotypy just by watching another. So don't isolate a horse that weaves or crib-bites, or hide it from others. Isolation causes stress and could lead to new stereotypies.

Effects on health

Stereotypies can affect a horse's physical health. The British Horse Society lists a higher risk of colic (particularly with crib biting and wind sucking), overdeveloped muscles, weight loss (some horses would rather perform the behaviour than eat), worn teeth from crib biting, and extra strain on tendons and ligaments from weaving.

What helps

First, see your vet. A new behaviour can be a sign of an underlying health problem, so talk to your vet first, and treat any physical cause.

Don't block the behaviour. Both the British Horse Society and World Horse Welfare advise against devices that physically stop the behaviour, such as cribbing collars and anti-weave grills, and against isolating the horse. They don't address the cause, can make stress worse, and may lead the horse to adapt its behaviour or develop new ones.

Change the horse's life. The most effective approach is to adapt the horse's management to encourage natural behaviour and reduce anxiety and frustration, following World Horse Welfare's 3Fs:

• Friends: turnout with at least one other horse for as long as possible. Stables should at least allow horses to see each other, and ideally to touch and groom each other. World Horse Welfare suggests "social stabling": lowering stable walls or adding large windows between stables, or housing horses in pairs.
• Forage: plenty of it, in varied forms and places. Small-holed haynets, hay balls, slow feeders and good-quality straw mixed into the hay make the ration last longer. Introduce any new feed gradually, over 10–14 days.
• Freedom: as much turnout as possible. If grazing must be restricted, an arena or a track system can still let a horse move with friends.

Enrich the environment. The British Horse Society describes enrichment as adding choice, variety and stimulation, for example:

• clear views of other horses, or a horse-safe stable mirror
• different surfaces and textures
• horse-safe herbs and scents (introduced outdoors, where the horse can move away)
• grooming and scratching
• quiet music for short periods, watching how the horse reacts

Introduce new things gradually and under supervision, outside the stable first, so the horse can move away if it is worried.

Be realistic. Management changes can reduce how often a horse performs a stereotypy, but it is unlikely ever to disappear completely, and stress may bring it back. If your vet finds no physical cause, a qualified equine behaviour professional can help find the reason behind it.

When a horse must be stabled or on box rest

Box rest can be very stressful. The British Horse Society suggests:

• asking your vet whether short turnout or grazing in hand is possible
• making sure the horse always has a calm companion it can see, and ideally touch, perhaps with a rota of other horses staying in
• offering plenty of forage of different kinds, at different heights and in different places
• giving it room and a deep bed to lie down in, because horses need to lie down to get full REM sleep
• spending quiet time grooming it and changing its scenery when it is safe to do so