Effect of turnout rugs on the behaviour of horses under mild autumn conditions in the United Kingdom

The use of rugs (blankets) for horses is commonplace as a protective measure to keep horses warm and dry in inclement weather, or to protect them from direct sunshine or insects under warmer conditions. However, rugs can also result in thermal or general discomfort, and information on horse responses to rugs is needed to inform owner decisions. The aim of this experimental study was to assess the effect of turnout rugs on the behaviour of horses under relatively benign weather conditions, looking for indications of either positive (protective) or negative (discomfort) effects. Ten healthy horses, accustomed to wearing rugs, were recruited from two sites in southern England, and observed for 30-minute sessions (15–24 sessions/horse, 172 in total). Observations were counterbalanced to allow approximately equal numbers of observations with turnout rugs on and off, each horse experiencing both conditions. Ambient temperature varied from 1 to 15 °C, and windspeed from 6 to 15 mph and no signs of heat or cold stress were observed during the study. Generalised estimating equations (GEE) were used to estimate the parameters of the regression models and to account for correlations between repeated observations on the same individual horses. Significant interactions between Rug status and Location were found for Standing, Grazing, Walking and Tail Swishing . Rug wearing was associated with decreased Walking, Tail swishing, and Grooming Self at both study sites, decreased Head Shaking at one site and increased Grazing at one site . Tail Swishing increased by 1.33 counts for every 1 °C rise in temperature, and decreased by 0.84 counts for every 1mph increase in windspeed Midges ( Culicoides spp) were informally observed at both sites and would have been more active at higher temperatures and lower windspeeds. Overall, the turnout rugs appeared to reduce this insect nuisance (as indicated by the reduced tail-swishing and head-shaking). However, the rugs were generally heavier than required for this purpose, and reduced Grooming Self and Walking could indicate restrictions imposed by rug design. In conclusion, when weather conditions are relatively mild (above 5 °C) horse welfare may be improved by the use of lightweight turnout rugs for fly protection. • Observing and recording behavioural change in horses based on rug wearing. • Increased tail swishing behaviour as temperature increased. • No tail swishing observed below 5 °C. • Reduced tail swishing behaviour with rug wearing. • Reduced walking and grooming behaviours with rug wearing.