The effect of domestication on horses: how do unwanted behaviours develop?

The effect of domestication on horses: how do unwanted behaviours develop?

Horses are prey animals (like most herbivores) which determines the anatomical and psychological evolution of the species and also drives selection in the population. Since horses needed to defend themselves from predators they have evolved to live in herds and developed various types of social behaviour.

Linear social hierarchy allowed the group to work in an organised way with every individual behaving according to its rank. Sharing the work is the great advantage of a herd: not every horse had to be on the lookout for predators continuously, the herd could feed or rest while a few (mainly older) horses would be on guard. The herds would move around large areas to find food (research indicates that the territory of a herd could be as large as 78 km2 [Schrenk, 1990]) and the horses needed a well developed musculoskeletal system and a cardio-respiratory system fit for constant movement to be able to control such a territory. Natural selection led to the animals becoming better fit for this purpose both in terms of conformation and fitness (only the best would survive and be able to produce offspring), and it would also contribute to the animals becoming more social. Some of the behaviours that make it possible to live life in a herd are inherited instincts, others are learned by observing older herd mates or by experience.

The life of the domesticated horse has changed significantly compared to its wild counterparts. Wild horses and horses living in natural settings (pastures) spend 16 hours a day feeding to satisfy their nutritional needs. Compared to this, the domesticated horse given concentrates spends significantly less time eating. This was not a problem until horses were out working all day but today most horses are not kept busy, and boredom leads to the development of unwanted behaviour.

Most of hobby horses don’t exercise much and spend most of their time in a stall or a paddock. In riding stables where the population is constant, horses can be kept in herds in a paddock and stay socially active. This unfortunately is not possible if there is a constant movement of horses because of safety and animal health concerns. In these cases, even when the horses are not allowed to make contact, at least allow the horse to see the other horses because not being able to exercise social behaviour might cause a build up of tension and aggression.

These changes to the horses’ living conditions such as limited space, built up energy and tension because of less exercise, as well as inappropriate housing and handling may all lead to the development of unwanted behaviour. The predisposition for unwanted behaviour is considered to be a heritable, polygenic trait, although learning from others (mainly the mare) may also contribute to the development of unwanted behaviours (Hecker, 1992).

The two most common unwanted behaviours caused by boredom are cribbing and windsucking, or the combination of both. Cribbing is where the horse places its upper teeth against a flat surface (e.g. feeder, side of the stall, wooden fences), arches its neck, and pulls backwards with its body swallow air. Some horses may do this by lunging their heads forward with the mouth open. This may have serious consequences for their health: air fills the stomach, causing a feeling of fullness and the horse will eat less, leading to a loss of body condition and in severe cases even to colic. Boredom or stress might also lead to weaving (a side-to-side movement of the horse’s neck and weight, which sometimes occurs with lifting and lowering of the feet) or stomping (stall walking). These unwanted behaviours can be prevented by providing consistent exercise and increasing the time spent out of the stall (i.e. in a paddock or pasture) with other horses. If a horse starts exhibiting one of these problems, immediate action should be taken because the longer the horse participates in an unwanted behaviour, the harder it is to treat.

Bad experience and inappropriate handling may also trigger behavioural problems. If horse shows dominance towards its rider or caretaker, it becomes a serious safety concern. Early training experience has a major impact in this regard as many foals learn these unwanted behaviours through inconsistent handling. Social behaviours are learned from herd mates at an early age and the foal carries these patterns throughout its life.
Horses can show aggression towards each other as well, the main cause for this is the lack of socialisation. Aggression may be evident in foals and predicts the future behaviour of the horse. Unfortunately, this is a vicious cycle: a horse that is aggressive towards other horses will be kept separated and will not learn appropriate social behaviour.
Biting, kicking and striking are also unwanted behaviours that pose a danger to people. The predisposition for these behaviours is heritable also but they will not appear unless triggered by something (e.g. bad experience).
Anxiousness is commonly caused by a frail nervous system (and thus is hereditary) but also develops frequently because of the impairment of a sensory organ (most probably the eye). The horse may exhibit anxiety in specific situations (e.g. afraid of the halter – pull back when tied) only, in these cases they can be retrained by gradually exposing them to the fearful situation.
Bad experiences (harsh handling) or sensitive mouth may lead to rearing or the horse becoming head-shy, moreover, in many cases this is the cause of bolting as well. These can also be prevented with care and consistency.

Eszter Szentirmai
Bonafarm-Bábolna Takarmány Ltd.

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