Abstract: The spontaneous behaviour and the apparent digestibility of dry matter and fibre and transit times of digesta were compared in four normal horses and four crib-biters. A technique was developed for measuring total gut transit times (TGTT) by using single-stool analysis of the passage of radio-opaque polyethylene markers. Longer TGTT were recorded in the crib-biters than in the normal horses but the orocaecal transit times did not differ. The crib-biters rested less than the normal horses.

Abstract: This article examines the recently completed equid ethogram and shows how analogues of social interactions between horses may occur in various human–horse interactions. It discusses how some specific horse–horse interactions have a corresponding horse–human interaction – some of which may be directly beneficial for the horse while others may be unusual or even abnormal. It also shows how correspondent behaviours sometimes become inappropriate because of their duration, consistency or context. One analogue is unlikely to hold true for all horse–human contexts, so when applying any model from horse–horse interactions to human–horse interactions, the limitations of the model may eclipse the intended outcome of the intervention. These limitations are especially likely when the horse is being ridden. Such analyses may help to determine the validity of extrapolating intra-specific interactions to the inter-specific setting, as is advocated by some popular horse-training methods, and highlight the subsequent limitations where humans play the role of the ‘alpha mare’ or leader in horse handling and training. This examination provides a constructive framework for further informed debate and empirical investigation of the critical features of successful intra-specific interactions.

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: We investigated lateralisation in horses because it is likely to be important in training and athletic performance. Thoroughbred horses (n = 106) were observed every 60 s for 2 h, when they were at pasture, and the position of the forelimbs in relation to one another was recorded. There was a population bias skewed to standing with the left forelimb advanced over the right (i.e. directional lateralisation). Using the first 50 observations, the distribution of preferences was 43 significantly left, 10 significantly right with 53 being non-significant (i.e. ambidextextrous). The strength of motor bias increased with age, suggesting maturation or an influence of training. The horses were also presented with an olfactory stimulus (stallion faeces) to score the tendency to use one nostril rather than the other. A significant preference to use the right nostril first was shown in horses under 4 years of age (n = 61) but not in older horses. Of the 157 horses tested for nostril bias, 76 had been assessed for motor bias and so were used for analysis of the relationship between laterality in the two modalities. There was no significant relationship between direction of foreleg motor bias and first nostril used, total number of inhalations or laterality index of nostril use. The absence of a correlation between laterality of nostril use and motor bias indicates that lateralisation of the equine brain occurs on at least two levels of neural organisation--sensory and motor--a finding that is consistent with other examples of lateralisation in species that have been examined in more detail.