Abstract: To explore the range of tensions used in reins to elicit specific movements from a range of horses, 22 horses of mixed age, sex, breed and training history were long-reined and ridden through a standard course. The reins contained embedded load cells so that tensions used to elicit specific movements could be measured and logged. These movements were categorised into `left turn', `right turn', `going straight' and `halt' and were separated for left and right rein tensions. The data were analysed using two-sample non-parametric Kolmogorov-Smirnoff tests and the differences between categories of horse and equipment were analysed with one-way analysis of variance. The tensions recorded in the reins were greater for long-reining than riding (median 5.76, Q25 3.9, Q75 13.3 N and median 5.29, Q25 9.3, Q75 2.9 N, respectively, P = 0.025), irrespective of whether the horses were ridden with a halter or a bridle or whether the test was completed at a walk or a trot. The tensions did not differ between the left and right reins (P > 0.05) when the horses were being driven or ridden in a straight line, providing evidence that an `even contact' was maintained. The rein tension required for going straight was less than for any other responses, showing that a lighter contact on the reins can be maintained between the application of specific stimuli. The rein tension required to elicit the halt response was greater than for any other response (P < 0.001). The rein tensions required to complete the course did not differ with the use of bridle versus the halter (P > 0.05). Clearly, a range of rein tensions is required for horses to elicit specific responses. In the interests of horse welfare and avoidance of habituation, those involved in equitation need to become aware of the tensions used in training horses and seek to keep them to a minimum. When rein tension can be measured objectively, this process can be easily implemented and monitored.

Abstract: The objective was to evaluate the efficacy of gymnastic training (GYM) and dynamic mobilization exercises (DMEs) on stride length (SL) and epaxial muscle size in therapy horses. Nine cross-bred hippotherapy horses that performed three, 25-minute therapeutic riding sessions per week throughout the study period were randomly assigned to three experimental groups: a control group in which the horses were sedentary with no additional physical activity; a group that performed DMEs; and a group that performed both DMEs and additional GYM including pelvic tilting, backing, turning in small circles, and walking over a raised rail to strengthen the abdominal and pelvic stabilizer muscles. The exercises were performed 3 days per week for 3 months, with evaluations at the start and end of the study. Stride quality was assessed by measuring SL and tracking distance (TD). Epaxial muscle size was monitored by ultrasonographic measurement of m. longissimus dorsi (LD) thickness and m. multifidi (MM) cross-sectional area. Paired t tests were used to compare within groups across time, and between groups were detected using analysis of variance with Tukey post hoc test. When walking at 1.3 m/s, SL and TD at walk increased significantly (P < .05) in horses subjected to GYM. Thickness of LD did not change in any group, but cross-sectional area of MM increased significantly by 3.55 cm2 (DME) and 3.78 cm2 (GYM). It was concluded that GYM training improved stride quality and DME-stimulated MM hypertrophy which has been shown to improve intervertebral joint stability in other species.

Abstract: Bringing the head and neck of ridden horses into a position of hyperflexion is widely used in equestrian sports. In our study, the hypothesis was tested that hyperflexion is an acute stressor for horses. Salivary cortisol concentrations, heart rate, heart rate variability (HRV) and superficial body temperature were determined in horses (n = 16) lunged on two subsequent days. The head and neck of the horse was fixed with side reins in a position allowing forward extension on day A and fixed in hyperflexion on day B. The order of treatments alternated between horses. In response to lunging, cortisol concentration increased (day A from 0.73 ± 0.06 to 1.41 ± 0.13 ng/ml, p < 0.001; day B from 0.68 ± 0.07 to 1.38 ± 0.13 ng/ml, p < 0.001) but did not differ between days A and B. Beat-to-beat (RR) interval decreased in response to lunging on both days. HRV variables standard deviation of RR interval (SDRR) and RMSSD (root mean square of successive RR differences) decreased (p < 0.001) but did not differ between days. In the cranial region of the neck, the difference between maximum and minimum temperature was increased in hyperflexion (p < 0.01). In conclusion, physiological parameters do not indicate an acute stress response to hyperflexion of the head alone in horses lunged at moderate speed and not touched with the whip. However, if hyperflexion is combined with active intervention of a rider, a stressful experience for the horse cannot be excluded.

Abstract: Horses are well able to form classical and instrumental associations and so the focus of much recent research has been on the stimulus control of instrumental learning. Horses appear to discriminate using spatial cues more easily than other stimulus features, as indicated both by the speed of initial task acquisition and by the extent to which acquired discriminations can be reversed. Phenomena associated with discrimination learning in laboratory animals, including generalisation and peak shift, have been demonstrated in horses. However, the ability of horses to classify stimuli into categories is more controversial. Although there is some evidence that horses may be able to form categories based on similarities in the physical appearance of different stimuli, there is currently no evidence that they are able to develop abstract concepts. Their performance on social learning tasks has also been poor. Few correlations are observed between the learning ability of individual horses on different tasks, suggesting that it may not be possible to classify individual horses as `good' or `poor' learners. Better learning performance by horses that are naturally calm is probably due to reduced interference in the learning process. Correct handling procedures can lower reactivity levels in horses, and may facilitate learning in some circumstances. Future research on equine learning needs to take into account the complex nature of equine social interaction. Studies on the effects of stress on learning, and on social and spatial cognition, are also particularly needed.

Abstract: Recent interest has focused on the advantage of intensively handling young foals as a means of producing more tractable horses, accustomed to humans and receptive to training. To date, the effect of this intensive handling, dubbed “imprint training” in the popular literature, has not been tested. The present study compares seven foals handled intensively as neonates with eight untreated controls. The handling protocol started from 2-8 h after birth and continued daily for a total of 5 days. The protocol consisted of a series of stimuli and experiences that were each repeated until the foal no longer resisted or reacted negatively. Subsequently, foals were tested before weaning, at 4 months of age. Results indicated that handled foals (HF) ranked higher than control foals (CF) in subjective ratings of calmness (*P<0.0117) and friendliness (*P<0.0001) and in several specific handling tasks (venipuncture *P<0.0220; placing in stock *P<0.0128). Although, in approach tests all foals but one allowed approach of a person to 4 m, significantly more HF approached the person than CF (P<0.0080). In stimulus tests, foals were presented specific stimuli to which they had been tested as neonates. Two of eight CF were too unruly and dangerous to test. Of foals that could be tested, CF required significantly more time to hook-up a heart rate monitor (**P<0.0055). Split-plot analysis indicated that HF had lower heart rates to initial left-sided stimuli, presented first, than CF (*P<0.0421). In response to right-sided stimuli, heart rate scores of CF were not significantly different from HF (P<0.2259), suggesting reduced reactivity over time due to a learning effect. Behavioral responses to specific stimuli did not differ between CF and HF, suggesting that neonatal handling has a general rather than specific effect on subsequent behavior. Cortisol concentrations were measured before and after testing and the difference calculated. All foals had higher post-testing levels than pre-testing levels. There was a significant difference between HF and CF, indicating greater reactivity among the CF (*P<0.050). In general, the results indicated that foals handled as neonates were more tractable and less reactive. Specific neonatal handling tasks, such as sticking a finger up the foal's nose or patting the bottom of the foot, seemed to have no beneficial effect on related tasks such as passing a nasogastric tube or tapping with a farrier's hammer at 4 months of age. Mechanisms for the observed effect of neonatal handling require further investigation.