Stable design influences relaxation and affiliative behavior in horses during short isolation bouts

Domesticated horses are often housed in individual stables for long periods where physical contact with conspecifics is not possible. Although common, this form of stable design is known to be detrimental to horse welfare. This study investigated the impact of short-term stabling (1-hour bouts) on behavioral expression using three stable conditions: a full wall, a barred window wall, and a half wall between paired horses in a within-subjects design study (N = 18). A mixed model (restricted maximum likelihood) was used to account for both stable condition and individual horse within the model. Behaviors influenced by stable design were those relating to vigilance and social affiliation. Horses spent a greater proportion of the observation time standing alert when in the full wall stable compared to the half wall stable (P = 0.009). The opposite is true of time spent standing and resting (P < 0.001). Compared to the window wall alone, horses in the half wall stable performed significantly more contact-seeking behaviors (P = 0.021). Horse owners often perceive stable design unimportant if only used for short periods of time, with the majority of their time budget spent at pasture with conspecifics. These results indicate that, even during short bouts of stabling, horses were more relaxed when stable design allowed them to engage in social behaviors with conspecifics and more vigilant when stable design left them physically isolated from conspecifics.