Are we over-rugging? A preliminary research article into how rugging affects clipped, stabled horses using the Orscana© rug-monitoring device

Introduction: There is little scientific research regarding rugging choices and habits and how they affect the horse. In the equine industry rugging is a practice that, alongside coat clipping, is common during the winter months. However, there are no industry guidelines on how one should rug appropriately without causing thermal discomfort to the horse. The equine thermalneutral zone is approximately 0^oC - 25^oC, a rather large range compared to that of a human's which is estimated to be at 14.8^oC - 24.5^oC. Differences in how each species perceive what is thermally comfortable makes rugging habits subjective to the owner's thermal comfort and thus can have an impact on the health and welfare of the horse. The aim of this study was to investigate if there is a need for changes in the equine industry by studying temperature and humidity under the rug, as well as activity of the horse while stabled in relation to rug weight.

Materials & Methods: This study examined the effects of rug weight during the winter (mean ambient temperature 5.8^oC) on 15 (6 Warmbloods, 3 Irish Sport Horses, 2 Welsh Crosses, 2 Thoroughbreds, 2 Thoroughbred crosses) horses of mixed age and sex through the rug-monitoring device, Orscana. The device was attached at the hip underneath the rug and synchronised to a smartphone through Bluetooth. All 15 horses wore rugs chosen by the owner and were subsequently monitored through the device for 12hrs overnight, for two nights. The Orscana took hourly recordings of temperature and humidity under the rug, as well as movement patterns categorised as: active, lying down, disturbed, or calm. IBM SPSS 24 was used for data analysis and correlation. All horses used in this study were in work of varying degree. Body temperature was not recorded prior to data collection. Due to the sample size the data collected was determined to be non-parametric, and thus Spearman Rank and Pearson correlation testing was used.

Results: Using Spearman-Rank and Pearson tests to conduct statistical analysis, it was found that rug weight and temperature under the rug had a significant positive correlation (P = 0.000; r = 0.18), as well as active movement (P = 0.000; r = 1). Recorded moisture levels under the rug were the only significant negative correlation to rug weight found (P = 0.000; r = -0.27). 

Discussion & Conclusion: While preliminary, this study shows that to some degree over-rugging occurred as mean temperatures for all horses were over the TNZ upper boundary. This means that horses wearing heavier rugs had significantly higher recorded temperatures than those that wore lighter rugs. Increases in activity with increased rug weight could be explained by thermal discomfort caused by the temperature beneath the rug, as horses begin initiating thermal behaviours to attain thermal comfort before reaching the upper boundary of the TNZ. No other activities recorded had any correlation to rug weight. The negative correlation between rug weight and humidity may have been related to the relative outdoor humidity rather than the humidity underneath the rug because during certain periods of data collection rain was forecasted. Unfortunately, relative humidity recordings were unable to be obtained. These results suggest that over-rugging may occur elsewhere within the industry. Further research into this is needed. This warrants industry-lead changes, and further education to the equestrian community on how to rug appropriately as to not cause heat-related illness and injury.