Abstract: The purpose of the present study was to gain more insight into the contribution of the forelimbs and hindlimbs of the horse to energy changes during the push-off for a jump. For this purpose, we collected kinematic data at 240 Hz from 23 5-year-old Warmbloods (average mass: 595 kg) performing free jumps over a 1.15 m high fence. From these data, we calculated the changes in mechanical energy and the changes in limb length and joint angles. The force carried by the forelimbs and the amount of energy stored was estimated from the distance between elbow and hoof, assuming that this part of the leg behaved as a linear spring. During the forelimb push, the total energy first decreased by 3.2 J kg(-1) and then increased again by 4.2 J kg(-1) to the end of the forelimb push. At the end of the forelimb push, the kinetic energy due to horizontal velocity of the centre of mass was 1.6 J kg(-1) less than at the start, while the effective energy (energy contributing to jump height) was 2.3 J kg(-1) greater. It was investigated to what extent these changes could involve passive spring-like behaviour of the forelimbs. The amount of energy stored and re-utilized in the distal tendons during the forelimb push was estimated to be on average 0.4 J kg(-1) in the trailing forelimb and 0.23 J kg(-1) in the leading forelimb. This means that a considerable amount of energy was first dissipated and subsequently regenerated by muscles, with triceps brachii probably being the most important contributor. During the hindlimb push, the muscles of the leg were primarily producing energy. The total increase in energy was 2.5 J kg(-1) and the peak power output amounted to 71 W kg(-1).

Abstract: REASONS FOR PERFORMING STUDY: Studies on the prevalence of behavioural disorders in horses and on associated risk factors have revealed inconsistent results. There are many studies on the neuropharmacological, surgical or mechanical therapy of stereotypies, but little is known about their causation. OBJECTIVES: To explore risk factors associated with the occurrence of behavioural disorders in horses. METHODS: A sample of horse owners, selected randomly and representative for Switzerland, was contacted in a postal survey. Answers were provided for 622 stables (response rate 35.2%). Individual data of 2,341 horses were examined with path analysis (multivariable linear and logistic regression), and adjustment made for possible confounding effects due to age and breed. RESULTS: Out of 60 possible risk factors, 11 were associated with the outcome at the univariable level (null-hypothesis path model) and 3 factors remained after the backward logistic regression procedure. Mature Warmbloods and Thoroughbreds, assessed by the owners to be reactive, fed 4 times a day and without daily pasture, had increased odds of displaying crib-biting, weaving and box-walking. Furthermore, indirect associations of 5 factors with the outcome were identified. CONCLUSIONS: The final logistic regression model of risk factors leads to the hypotheses that causal prevention of stereotypic behaviours should be based upon housing and management conditions which allow tactile contact with other horses (e.g. mutual grooming), daily free movement (paddock or pasture), as well as the provision of high amounts of roughage but of little or no concentrates. POTENTIAL CLINICAL RELEVANCE: It is one of the aims of population medicine to prevent the development of behavioural disorders. Further research is needed to test the concluding hypotheses in experimental studies or to verify them in the context of similar observational studies.

Abstract: In the past, equine color vision was tested with stimuli composed either of painted cards or photographic slides or through physiological testing using electroretinogram flicker photometry. Some studies produced similar results, but others did not, demonstrating that there was not yet a definitive answer regarding color vision in horses (Equus caballus). In this study, a pseudoisochromatic plate test--which is highly effective in testing color vision both in small children and in adult humans--was used for the first time on a nonhuman animal. Stimuli consisted of different colored dotted circles set against backgrounds of varying dots. The coloration of the circles corresponded to the visual capabilities of different types of color deficiencies (anomalous trichromacy and dichromacy). Four horses were tested on a 2-choice discrimination task. All horses successfully reached criterion for gray circles and demonstration circles. None of the horses were able to discriminate the protan-deutan plate or the individual protan or deutan plates. However, all were able to discriminate the tritan plate. The results suggest that horses are dichromats with color vision capabilities similar to those of humans with red-green color deficiencies.

Abstract: The efficacy of questionnaire-based personality assessment has been shown in a variety of animal and human personality studies. There has been a recent increase in questionnaire-based studies focussing on equine personality but with a lack of comparability to studies on other species. The aim of this study was to test the reliability of an assessment method originally developed for primates and demonstrate reliability using three criteria (1) assessments by independent observers must agree with one another, (2) these assessments must predict behaviours and real-world outcomes and (3) observer ratings must be shown to reflect genuine attributes of the individuals rated, not merely the observer's implicit personality theories about how traits co-vary. The personality of 61 horses (Equus caballus) was assessed using a questionnaire constructed of 30 behaviourally defined adjectives (BDAs). Horses were each assessed by three judges, in addition to a total of 2 h behaviour observations recorded per horse. Rater agreement was demonstrated for 72.1% of the horses and 25 of the BDAs. Principal component analysis was carried out on the rating data and revealed six underlying personality components that were labelled “dominance”, “anxiousness”, “excitability”, “protection”, “sociability” and “inquisitiveness”. Component scores for horses were correlated against behavioural observations for the same horses and revealed significant correlations with 20 of the recorded behaviour variables. Correlations between specific components and their associated behaviours were logical and consistent with the types of behaviours that would be expected to be linked with such personality types. The data were shown to meet all three criteria and provided strong evidence that the assessment method was reliably measuring horse personality.

Abstract: To achieve optimal performance in equine sports as well as in leisure not only the physical abilities of the horse should be considered, but also the horse's personality. Besides temperamental aspects, like emotionality, or the horse's reactivity towards humans in handling situations, the learning ability of the horse is another relevant personality trait. To study whether differences in learning performance are consistent over time and whether individual learning performance differs between learning tests or is affected by emotionality, 39 young horses (Dutch Warmblood) were tested repeatedly in two learning tests. An aversive stimulus (AS) was used in one learning test (the avoidance learning test) and a reward was used in the other learning test (the reward learning test). During both learning tests behaviour as well as heart rate were measured. Each test was executed four times, twice when horses were 1 year of age, and twice when they were 2 years of age. Half of the horses received additional physical training from 6 months onwards. In both tests horses could be classified as either performers, i.e. completing the daily session, or as non-performers, i.e. returning to the home environment without having completed the daily session. There were some indications that emotionality might have caused non-performing behaviour, but these indications are not convincing enough to exclude other causes. Furthermore, there seem to be no simple relationships between measures of heart rate, behavioural responses putatively related to emotionality and learning performance. Horses revealed consistent individual learning performances within years in both tests, and in the avoidance learning test also between years. There was no significant correlation between learning performances in the avoidance learning test and the learning performances in the reward learning test. It is concluded that individual learning abilities are consistent over a short time interval for an avoidance learning test and a reward learning test and over a longer time for the avoidance learning test. Furthermore, results indicate that some horses perform better when they have to learn to avoid an aversive stimulus while others perform better when they are rewarded after a correct response. It is suggested that these differences may be relevant to design optimal individual training programmes and methods.