Work it out: Investigating the effect of workload on discomfort and stress physiology of riding school horses

Riding schools play an essential role in the equestrian industry and in education. These establishments are reliant on horses to work for numerous hours, often with riders of different abilities. However, little is known about the impact workload has on the well-being of these horses and effective monitoring of welfare is required for animal- based industries to maintain their Social Licence to Operate. The aim of the current study was to investigate how the quantity of work carried out by riding school horses affects their behaviour and physiology, providing evi- dence as a starting point to identify suitable levels of work that riding school horses can be used for before their welfare is compromised. Horses (n = 30) were observed 1–2 h after completing their workload on a day of Rest, Moderate (1–2 h) and Hard work (3–4 h). Infrared thermography of eye temperature (IRT) and heart rate variability (RMSSD) were measured as indicators of arousal. The Horse Grimace Scale (HGS) was scored treatment-blind to measure discomfort and pain. No significant difference was found between RMSSD or eye temperature depending on the level of workload, indicating subjects were able to cope with increasing demands. However, there was a significant difference in the HGS score between Rest, Moderate and Hard work (p < 0.001). This indicates a greater degree of discomfort following an increase in hours of work. Another possible expla- nation for the increase of the HGS score is that tiredness can influence the presence of some of the FAUs (e.g., backward ears and orbital tightening) making it more difficult to discriminate between whether a horse was in pain or the increased score is a consequence of being physically tired after the work. Findings indicate that 1–2 days of working 3–4 h can be appropriate in horses conditioned to the work in well managed riding facilities, however further research is needed to determine how long increased HGS lasts to determine how often days of hard work may occur without impacting welfare.