Abstract: Although housing horses in single stalls limits their natural behavior to a great extent, this housing system is widespread in Germany, especially for competition horses. To improve the welfare of this system, free exercise on pastures or paddocks is deemed suitable, but it is also feared because of injuries and decreased willingness or motivation to perform. In the present study, three treatments were investigated with regard to their effect on the behavior of six competition horses in the stable, behavior during training, and on their degree of stress: daily training without free exercise (no turnout [NT]), solitary turnout for 2 hours after training, and 2-hour turnout in groups of two after training (group turnout). The horses' behavior in the stable was continuously analyzed through video recordings (2 pm to 6 am) on 3 days at the end of each treatment. The degree of stress was evaluated daily by heart rate variability at rest. The behavior during training was evaluated by a questionnaire answered by the riders, and the distance covered during training was measured by global positioning system. When NT was allowed, the horses showed less lying in the stable compared with the treatments with turnout. Heart rate variability measurements resulted in great individual differences, but generally, there was a higher degree of stress shown with the treatment NT according to the following parameters: standard deviation of inter-beat-intervals (SDNN), square root of the mean of the sum of the squares of differences between successive inter-beat-intervals (RMSSD), and ratio between low frequency and high frequency (LF/HF). The willingness to perform was evaluated as being slightly better in the treatments with turnout than in the treatment without turnout.

Abstract: Assessing the animal welfare state is a challenge given the subjective individual cognitive and emotional processing involved. Electroencephalography (EEG) spectrum analysis has proved an ecologically valid recording situation to assess the link between brain processes and affective or cognitive states in humans: a higher slow wave/fast wave ratio has been associated with a positive internal state. In particular, a high production of theta power (3-8 Hz) has been related to positive emotions. On the other hand, it has been hypothesized that a left hemisphere (LH) dominance may be associated with a better welfare state. Here, we test the hypothesis that individual differences in the resting-state quantitative EEG power spectrum of adult horses (N = 18) and its lateralization pattern may reflect individual subjective perception of their conditions of life and welfare state. The results show clear individual differences in the proportions of the different waves and their inter-hemispheric distribution. Three different EEG power spectrum profiles were highlighted, from a bilateral predominance of theta waves in horses in a more positive welfare state to a bilateral predominance of beta waves in horses with clear expressions of compromised welfare. Interestingly, particular correlations were found between wave power activity and welfare parameters. We found a negative correlation between the number of stereotypic behaviours per hour and the median proportion of theta waves in the left hemisphere. and between the overall state (total chronic stress score) of welfare and gamma production in the right hemisphere (RH). These findings go along the hypothesis of a particular involvement of the left hemisphere for positive processing and of the right hemisphere for negative processing. However, the pattern of laterality did not appear as the most important feature here as both extreme clusters in terms of welfare showed bilateral predominance of one wave type. It is possible that hemispheric specialization makes more sense during acute emotion-inducing conditions rather than in this resting-state context (i.e. in absence of any high emotion-inducing stimulation), although the opposition gamma versus theta waves between both hemispheres in the horses with an intermediate welfare state is noticeable and intriguing. It seems that bilateral but also LH theta activity is a promising neurophysiological marker of good welfare in horses, while a bilateral or RH high production of gamma waves should alert about potential welfare alterations. Quantitative resting-state EEG power spectrum appears as a highly promising tool for exploring the brain processes involved in the subjective perception of chronic welfare, as a useful complementary tool for welfare assessment.

Abstract: The effect of stabling for the first time on the behaviour and welfare of young and naïve horses has not yet been studied in detail. In this study we examined the effect of two typical housing systems on their subsequent behavioural and physiological responses upon first time stabling. Thirty-six 2-year-old Dutch warmbloods, 18 geldings and 18 mares were included in the study. Half of the horses were stabled in individual stables (10.5m2) and the other half in pair housing (48m2 for two horses). The study lasted 12 weeks. At the end of the study the physiological and temperamental responses of the horses on the different treatments was tested using a CRF challenge test (to test the HPA-axis function) and a Novel Object test (to test temperamental differences) respectively. Especially in the first week after stabling pair housed horses spent more time eating whereas individually housed horses spent more time either standing vigilant or sleeping. Stress-related behaviours like neighing, pawing, nibbling and snorting were all displayed significantly more frequently in the individually housed horses (P<0.01). At the end of the study 67% of the individually housed horses was seen performing one or more stereotypies (P<0.01). The cortisol response and ACTH response on the CRF challenge test were lower for horses in the individually housed boxes. It is suggested that this depression in socially isolated animals is caused by a desensitisation of the HPA axis in response to stress-induced elevations in ACTH and cortisol. In general there was no effect of the treatment on the reactivity of the horses during the Novel Object test. However, there were significant relations between the responses of horses in the Novel Object test and in the stable environment. It is concluded that sudden isolated stabling is stressful to young and naïve horses, resulting in a high prevalence of stereotypies and abnormal behaviours. This study also provided some support for the notion that social stress in horses may be associated with a blunted adrenocortical response to CRF challenge. The finding that responses of horses to a behavioural test are correlated with home environment behaviours suggests that individual horses exhibit consistent behavioural traits across different contexts, and opens the possibility of using behavioural tests in horses to predict more general underlying behavioural characteristics.

Abstract: The aim of the study was to determine the effect of music featured in the barn, on the emotional state of race horses. Seventy 3-year-old Purebred Arabian horses in their first race season were divided into experimental group (EXP) of 40 horses and control group (CNT) of 30 horses and placed in separate barns. The EXP was subject to specifically composed music featured in the barn for 5 hours in the afternoon during the whole study. The emotional state in the horses was assessed at rest, saddling, and warm-up walk under rider. Measurements were taken six times, every 30 to 35 days, starting from the beginning of featuring the music. The horse's emotional state was assessed by cardiac activity variables. The music effect on the emotional state was also considered with regard to the horse's performance estimated by race records. The cardiac activity variables were compared with repeated measures design, whereas race records were analyzed with analysis of variance generalized linear model. The music positively affected the emotional state in race horses. The influence was noticeable already after the first month of featuring the music and increased in the second and third months. Despite the fact that later the variables began to return to initial levels, a positive effect of the music on prizes won by the horses in the EXP compared to the CNT was found (P < .05). The results suggest that the music may be featured in the barn, preferably for 2 to 3 months as a means of improving the welfare of race horses.

Abstract: Vision, hearing, olfaction, taste, and touch comprise the sensory modalities of most vertebrates. With these senses, the animal receives information about its environment. How this information is organized, interpreted, and experienced is known as perception. The study of the sensory abilities of animals and their implications for behavior is central not only to ethology but also to animal welfare. Sensory ability, perception, and behavior are closely linked. Horses and humans share the five most common sensory modalities, however, their ranges and capacities differ, so that horses are unlikely to perceive their surroundings in a similar manner to humans. Understanding equine perceptual abilities and their differences is important when horses and human interact, as these abilities are pivotal for the response of the horse to any changes in its surroundings. This review aims to provide an overview of the current knowledge on the sensory abilities of horses. The information is discussed within an evolutionary context and also includes a practical perspective, outlining potential ways to mitigate risks of injuries and enhance positive horse-human interactions. The equine sensory apparatus includes panoramic visual capacities with acuities similar to those of red-green color-blind humans as well as aural abilities that, in some respects exceed human hearing and a highly developed sense of smell, all of which influence how horses react in various situations. Equine sensitivity to touch has been studied surprisingly sparingly despite tactile stimulation being the major interface of horse training. We discuss the potential use of sensory enrichment/positive sensory stimulation to improve the welfare of horses in various situations e.g. using odors, touch or sound to enrich the environment or to appease horses. In addition, equine perception is affected by factors such as breed, individuality, age, and in some cases even color, emphasizing that different horses may need different types of management. Understanding the sensory abilities of horses is central to the emerging discipline of equitation science, which comprises the gamut of horse-human interactions. Therefore, sensory abilities continue to warrant scientific focus, with more research to enable us to understand different horses and their various needs.