Elsevier

Physiology & Behavior

Volume 104, Issue 3, 1 September 2011, Pages 454-463
Physiology & Behavior

Equine behaviour and heart rate in temperament tests with or without rider or handler

https://doi.org/10.1016/j.physbeh.2011.05.010Get rights and content

Abstract

The aim of the present study was to compare horses' heart rate (HR), heart rate variability (RMSSD, pNN50) and behaviour in the same temperament test when being ridden, led, and released free. Behavioural measurements included scores and linear measurements for reactivity (R), activity (A), time to calm down (T) and emotionality (E), recorded during the approach (1) and/or during confrontation with the stimulus (2). Sixty-five horses were each confronted 3 times (1 ridden, 1 led, 1 free running in balanced order) with 3 novel and/or sudden stimuli. Mixed model analysis indicated that leading resulted in the lowest (P < 0.05 throughout) reactions as measured by A1, A2, E1, E2, R2, and pNN50 while riding produced the strongest (A1, T2, HR, RMSSD, pNN50) or medium (E1, E2, R2) reactions. Free running resulted either in the strongest (A2, E1, E2, R2) or in the lowest (A1, T2, HR, RMSSD, pNN50) reactions. The repeatability across tests for HR (0.57), but not for RMSSD (0.23) or pNN50 (0.25) was higher than for any behavioural measurement: the latter ranged from values below 0.10 (A1, A2, T2) to values between 0.30 and 0.45 (E1, E2, R2). Overall, the results show that a rider or handler influences, but not completely masks, the horses' intrinsic behaviour in a temperament test, and this influence appeared to be stronger on behavioural variables and heart rate variability than on the horses' heart rates. Taking both practical considerations and repeatabilities into account, reactivity appears to be the most valuable parameter. Emotionality and heart rate can also yield valid results reflecting additional dimensions of temperament although their practical relevance may be less obvious. If a combination of observed variables is chosen with care, a valid assessment of a horse's temperament may be possible in all types of tests. However, in practice, tests that resemble the practical circumstances most closely, i.e. testing riding horses under a rider, should be chosen.

Research highlights

► We compared equine behaviour in temperament tests with and without handler/rider. ► Heart rate, emotionality and reactivity show acceptable repeatabilities. ► Measures of activity and heart rate variability show rather low repeatabilities. ► Equine temperament test yields valid results with or without human rider or handler.

Introduction

Temperament tests for horses receive increasing attention in both research and practical horse breeding. Although environmental conditions such as raising and handling experiences [1] can influence and even superimpose the animal's genetic predisposition to behave in a certain way, genetic factors generally determine equine temperament in a substantial way. For example, breed [2], [3] and sire lines [2], [4], [5] significantly influence aspects of equine temperament. Studies by Burger et al. [6] also indicate that temperament is under strong genetic control, demonstrating that different aspects of temperament in foals of embryo transfer were influenced significantly by temperament of the foals' genetic parents, but hardly by the temperament of the foster dams. Emotional reactivity to fear-inducing stimuli as well as cognitive capabilities appears to be under particularly strong influence of genetics [3]. In comparison, traits such as dominance status and sociability are influenced to a lesser degree by genetics [3]. Although a few studies [7] failed to detect a significant influence of specific foal handling regimens on later handling ease, human handling and training can be applied to deliberately influence horse behaviour in test situations. For example, handling around weaning improved later handling ease, whereas just a single negative experience of foals with a veterinarian e.g. for vaccination may alter their otherwise friendly attitude towards human beings [1]. Similarly, long-time experience with specific caretakers [8], early experiences [1], [7], [9], [10], particularly around weaning [1], [10], [11] and handling of the dam in presence of the foal [12] can alter equine behaviour considerably. Housing conditions [13], [14], the presence of other horses [15], type of training [16] or the rider's riding style [17] can likewise influence aspects of behaviour. As a consequence, when using competition data for genetic evaluation in riding horses, factors such as testing location [18] and the rider and/or the rider skill level [19], [20] are introduced as a correction factor into the model.

Recently, a variety of temperament- and related behaviour tests have been validated [21], [22], [23], [24], [25] and used for assessing equine personality [9], [10], [26]. Consequently, as more and more breeding associations realise the importance of behaviour traits such as temperament, a move from subjective scoring towards a more objective assessment using such temperament tests can be seen [27], [28], [29]. Typically, these temperament tests subject the horse to several novel [22], [30] and/or sudden stimuli [5], [31], in order to assess the horses' fear and anxiety reactions, and they may [4], [22] or may not [31] include human handling. However, the question of whether or not humans should be part of these tests is still subject of a controversial debate. Opponents of having humans involved in temperament tests emphasise the importance of excluding additional variables that could influence the animals' reactions in the test. Proponents, on the other hand, argue that in the case of livestock and companion animals a person can and should be an integral part of the test in order to increase the applied value of the test. This latter view is supported by studies [32], [33] showing that extreme standardisation of animals, environment and testing procedures can lead to incapacitation of research results. Therefore, the aim of the present study was to compare horses' heart rate and behaviour in the same temperament test when they are ridden, led, or running free, i.e. when given the opportunity to explore the stimuli without the influence of a handler or rider.

Section snippets

Horses, handlers and facilities

A total of 65 Hanoverian Riding Horses, including 6 mares, 7 geldings and 52 stallions, ranging between 3 and 19 years of age were tested. Prior to testing, horses were naïve to the stimuli and had not been exercised that day to ensure a similar level of physical exertion in all horses. Horses were housed in single stalls allowing for visual, olfactory, auditory and some tactile contact, however, tactile contact was limited by vertical bars to nose–nose contact. Prior to being started under the

Test-type

Test-type significantly (P < 0.05) influenced all variables (Table 2): riding was associated with strongest (A1, T2, HR, RMSSD, pNN50) or medium (A2, E1, E2, R2s) reactions when compared to free-running or leading. In contrast, leading was mostly associated with weakest reactions, as measured by A1, A2, E1, E2, R2s, and pNN50 but never with strongest reactions except for HR and RMSSD. For free-running, results were associated either with strongest reactions (variables A2, E1, E2, R2s) or the

Discussion

Individual differences in personality have been suggested to have evolutionary adaptive value [40] and have been detected in numerous species studied. Various definitions of temperament and components that constitute temperament have been given [41], and there is little consensus on which definition to use in human and/or animal studies. For the purpose of the present study we adopted the definition of temperament describing an individuals' biologically rooted behaviour tendencies that remain

Conclusion

The present study shows that a rider or handler influences, but not completely masks, the horses' innate behaviour in a temperament test. Based on both repeatabilities and practical considerations, reactivity appears to be the key component to be measured in a temperament test. Although their practical relevance is less evident, emotionality and heart rate also remain fairly independent from handler or rider influence and can provide additional information about a horses' temperament. In

Acknowledgements

We are very grateful to the horse owners and volunteer riders, and in particular to Dr. Axel Brockmann and his staff from the Lower-Saxony State Stud Celle and the stallion testing station Adelheidsdorf for their terrific support of this study. A special thanks to María Díez León for her support in the literature search.

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