All about stereotypies

When you think about it, we ask our horses to live relatively unnatural lives. Instead of allowing them to roam freely as they would in the wild, we confine them in fields and stables, often with only one or two companions (selected by us and sometimes a source of frustration) as a replacement for a herd with its varied social interactions. Fortunately, the vast majority cope quite happily with this more restricted, yet safer, way of life. Some, however, do not and that’s when we might see behaviour developing that scientists call stereotypic.

Played on repeat

Stereotypy is the scientific term for any repetitive behaviour. In horses, the most common are crib-biting, windsucking, weaving and box walking, all of which used to be thought of as harmful and referred to as vices. We now understand them to be signs of sensitivity and reactions to particular situations to include feeling pain, frustration, excitement, pleasure and arousal. 

What all these, apparently diverse, situations have in common is that they lead to stimulation of dopamine receptors in the brain. Some – such as crib-biting when eating tasty food – do this by increasing levels of beta-endorphins in the blood, which then stimulate dopamine release, with a resultant increase in sensitivity to it. Conversely, others, such as weaving when frustrated, affect dopamine production directly. 

Did you know?

Dopamine is a neurotransmitter that plays a part in a number of body functions, most notably in the brain’s perception of pleasure, motivation and reward.

Associated behaviour

Given enough stimulation, any horse can develop a stereotypy, and it will relate to the particular behaviour being done at the time when the relevant brain stimulation reached a critical point. 

Horses spend most of their time eating or moving, so the most common stereotypies relate in some way to these activities. This behaviour is then isolated from other actions normally seen at those times, looking bizarre on its own, especially when not associated with its triggers or goals.

For example, crib-biting horses perform only the end part of biting movements and the beginning of swallowing. Then, if the swallowing results in air intake, this is burped back out again, making the characteristic noise called windsucking. 

Pacing stereotypies fit the stable they develop in, including any turns, looks over the door or steps over obstacles, and these can then look very odd if performed elsewhere. 

Did you know?

Moving yard is a common cause of stereotypy development. Watching how the pattern fits the environment can help you work out whether it started in the old or the new home.

Cause and effect

In most domestic situations, only horses born with greater sensitivity to dopamine develop stereotypies, and there is a strong genetic element to this. In this way, these horses are useful indicators of what are deemed to be arousing or frustrating situations. By knowing the management changes that can reduce associated stereotypies, we can use the information gained to help all horses living in that same manner. 

A word of caution. Sudden onset of a stereotypy or an increase in its frequency without any obvious changes in lifestyle can be due to pain, so it’s important to eliminate this possibility before trying ways to manage the behaviour. It’s also worth noting that horses prone to stereotypies tend to be more difficult to sedate and twitch.

Did you know?

Windsucking horses do not swallow air or develop colic because of it. However, chronic digestive disorders causing pain may cause stereotypies, and that may be how this myth originated.

Top tip

If your horse’s stereotypy is causing a problem, there are drugs your vet can prescribe to humanely prevent it in the short term. 

Busting the myth

A key feature of stereotypic behaviour is its strictly repetitive nature. Essentially, a stereotypy is a coping mechanism that gives the brain repetitive, predictable feedback, which then calms and reduces arousal. As a result, it’s cruel and counterproductive to try to physically prevent a stereotypy. Horses do not copy stereotypic behaviour and it is not learnt, so isolating or punishing a horse is only likely to increase frustration or pain and, in turn, stereotypy performance.

In fact, most stereotypic behaviour does not harm the horse. Many horses weave at feeding time, or they might paw in a stereotypic way when eating a bucket feed or stand with a raised leg, which is also a stereotypy – an isolated part of a bigger movement. 

Nevertheless, some stereotypies can be undesirable. For example, doors and fence posts can be damaged or the ground worn excessively, while horses who crib-bite on metal will wear down their teeth in a characteristic pattern. Similarly, horses who weave when in a trailer can make driving dangerous. So, it’s often the knock-on effect that makes owners want to eliminate the stereotypy, rather than the stereotypy itself that’s the problem. 

Top tip

To avoid frustration and arousal in your horse, always use clear and consistent signals when handling and riding him.

Did you know?

Boredom is a lack of stimulation, whereas stereotypies are caused by too much, or confusing, brain stimulation. In fact, toys that deliver food bit by bit to relieve boredom can actually lead to frustration and an increase in stereotypic behaviour.  

Practical solutions

The key to good, long-term management is facilitating safe expression of the stereotypy (while making sure your horse is healthy) and also reducing arousal and frustration.

Protect teeth and the parts of the stable and field used for stereotypies by covering these with rubber matting or split plastic drainage pipes. 

Did you know?

Boredom is a lack of stimulation, whereas stereotypies are caused by too much, or confusing, brain stimulation. In fact, toys that deliver food bit by bit to relieve boredom can actually lead to frustration and an increase in stereotypic behaviour.  

Avoidance tactics

Frustration and confusing feedback to the brain stimulate dopamine production, and the most common reason behind this is the way horses are fed. They receive all their nutrition relatively quickly from grass, hay and concentrated feeds, without having to do the work over many hours in the way their brain evolved to expect. The brain then receives mixed messages and this creates the stereotypic elements needed to satisfy it. As a result, one of the best ways to reduce stereotypies in horses is to increase time spent eating to up to around 12 hours a day.

To do this in the stable, try hanging two or three small-holed haynets inside each other in different corners, or sprinkle his concentrate feed through his forage. Or, for good-doers, feed stemmy, coarse hay mixed with clean straw. When your horse has to work for his feed, his brain is receiving the right information and the endorphin rush caused by a sudden, large amount of tasty food is avoided.

Top tip

Strict routines can create frustration but so does unpredictability. Try to find a balance between the two to encourage calmness.

Did you know?

Increasing your horse’s fitness can reduce his endorphin levels, making him less prone to developing a stereotypy.

Feed support

Some feedstuffs (such as cereals) are very high in an amino acid called tyrosine, which increases dopamine availability – not ideal in horses who are prone to stereotypies. Speak to a nutritionist for advice on how best to provide your horse with the energy he needs for his work while minimising his tyrosine consumption by minimising cereals and using oil and grass nuts or alfalfa pellets to increase energy and protein content.

Conversely, some feedstuffs – for instance, rice bran oil – are very high in an amino acid called tryptophan, which makes a substance called serotonin in the brain. This has the opposite effect to dopamine, so supplementing with this can be very useful. Tryptophan supplements (such as some calmers containing high levels of it) have been shown to reduce pacing, for example.

A positive approach 

While it’s virtually impossible to completely eradicate a stereotypy – certainly without causing stress to your horse – with some thought and trying out different ways of caring for him, it should be possible to manage it. And, on a final positive note, horses with stereotypies tend to learn more quickly.