Effect of work on body language of ranch horses in Brazil

Abstract

The horses' responses to exercise are commonly monitored using physiological variables, nonetheless physical and mental states can also be expressed through body language. The aims of this study were: (i) to identify how facial expressions and other behavioural variables change in ranch horses after a routine workday, and (ii) to investigate if these changes can be used as indicators of physical tiredness by relating them to known variables of physical fitness and workload. Fourteen crossbred ranch horses were assessed pre-and post-workday on two farms, recording the body language, physiological and workload variables. Statistical analysis consisted of four stages: (i) comparisons between the sampling times (pre-vs postworkday) using linear mixed-effects models with repeated measures and a paired Wilcoxon test; (ii) selection of the most powerful variables by applying Kaiser-Meyer-Olkin test and principal components analyses (PCA); (iii) evaluations of the relationships within these selected variables utilizing PCA and Spearman rank coefficients; and (iv) identifying a critical level of the most robust behavioural indicators using a non-hierarchical cluster analysis. Results showed that after a workday the horses increased the frequency/duration of body language indicative of resting. They also decreased the frequency/duration of body language indicative of attention and movements to avoid flies. However, some of these behaviours are also shown when horses are in pain, leading us to suggest that some ranch horses were probably experiencing a combination of of tiredness and slight soreness. Of particular interest, because of the ease with which it can be assessed on the farm and generalized to other situations, we suggest that the frequency of shifting weight between the forelegs has potential to be used as an indicator of physical tiredness in horses. The results can also be used in the development of tools to improve the welfare of ranch horses as well as horses used in other activities, although more research is needed to validate this assumption.

Validation of the UNESP-Botucatu pig composite acute pain scale (UPAPS)

“…Nonhierarchical cluster analysis was performed, applying the "maximum" distance and the "Ward. D2" method using the total score of UPAPS and NS [51], followed by the Kruskal-Wallis test to assess the difference between the groups.…”

Towards Machine Recognition of Facial Expressions of Pain in Horses

“…This is not surprising, since pain is regarded as an internal stressor and can activate the hypothalamo-pituitary-adrenal axis [100], but it may impair the specificity of face-based pain scales, since high levels of stress may be present during pain evaluations. Furthermore, affective states such as fatigue or residual effects from pharmacological sedatives or anesthetics in the clinical setting may affect how the horse displays pain [101].…”

Facial Expressions of Horses Using Weighted Multivariate Statistics for Assessment of Subtle Local Pain Induced by Polylactide-Based Polymers Implanted Subcutaneously

“…Facial features in horses have been studied after surgical castration procedures [ 45 ], in animals with acute colic syndrome [ 46 ], in pain inducement with the use of a tourniquet on the foreleg and a topical application of capsaicin [ 47 ], in animals with acute laminitis [ 48 ], in horses mounted during competitions [ 5 , 49 ], in the induction of positive emotions [ 50 ], and in the evaluation of the effect of exercise on ranch horses [ 51 ]. Recently, studies have used the face to evaluate dental disorders [ 52 , 53 ], the calming effect of aromatherapy [ 54 ], the effect of transportation and social isolation [ 55 ], sedation [ 56 ], and induced orthopedic pain [ 4 , 57 ].…”

“…For example, dilated nostrils are interpreted as postoperative pain [ 45 ] and orthopedic pain [ 57 ]. However, they were seen during transportation and social isolation [ 55 ] as well as after physical exercise, due to hyperventilation [ 51 ]. Another more complex example is partially or entirely closed eyes, which occurred after castration, being interpreted as pain [ 45 ], but which were also observed after physical exercise as signs of physical tiredness [ 51 ] and relaxation [ 50 ].…”