A Preliminary Investigation into the Relationship Between Under-Rug Temperatures and Sleep-Related Behavior in Stabled Horses Using Non-Invasive Temperature Measures

Stabled horses are managed within a domestic environment, where the effects of artificial lighting and bedding on sleep have been reported. Beyond the environment, equine husbandry practices such as rugging or clipping are influential on equine thermoregulation. However, the influence of these practices on sleep and related behaviors is unknown, despite the link between core body temperature and the occurrence of sleep. The aim of this pilot study was to investigate the viability of using novel temperature recording equipment to determine whether a relationship between under-rug temperature and sleep-related behavior could be detected. Under-rug temperatures were measured using Thermachron iButtons© at 10-minute intervals across five nights, while closed-circuit television camera equipment enabled continuous focal observations of sleep-related behavior. Duration of behavioral states according to a pre-determined ethogram was recorded between the hours of 00:00 and 07:00 for four stabled horses. Overnight environmental temperatures were reported between -6 °C and 4 °C. Mean under-rug temperature from all horses across five nights was 22.91 ± 0.12 °C (minimum 14.0 °C, maximum 34.0 °C) and was different between nights and between individual horses. No significant relationships were identified between under-rug temperatures and total duration of behavioral states. While the iButtons demonstrated the capacity to measure temperatures, several recommendations are made for future studies based on this foundational work. The relationship between under-rug temperature and sleep behavior warrants further investigation, which in the future could include data on sleep onset or sleep quality.