Evaluation of Short-Term Stall Size Housing on the Behavior and Welfare of Domestic Horses (Equus caballus).

Single-stall housing is a common system used for horses in various settings, including racing stables, riding schools, teaching and research facilities. Adequate stall space is necessary for horses to lie down and make postural adjustments, both of which are essential for equine rest and welfare. The Guide for the Care and Use of Laboratory Animals recommends a stall size of 144 ft2. However, not all stalls meet this size requirement, and there is limited literature supporting its use in terms of animal welfare. This study used a crossover design to compare behavioral and physiologic variables indicative of welfare of horses housed in the standard recommended 144-ft2 stall compared with a smaller stall (136 ft2) to determine whether the smaller stalls affected horses' welfare and behavior. Eight horses (1,380-1,640 lb) were paired with preferred associates resulting in 4 pairs. One horse from each pair was randomly assigned to be housed in either the standard stall (144 ft2) or the smaller stall (136 ft2) for 4 days (from Monday morning through Friday morning), while the paired horse was housed in the opposite-sized stall. After this initial stall period, all horses were turned out to pasture for 9 days before being housed in the alternate-sized stall for an additional 4 days. Hay consumption, fecal output, and serum cortisol were quantified daily. Movement and duration of recumbency were measured with an accelerometer, and continuous video recordings of all horses were obtained while housed in the stalls (total of ∼96 hours per horse per stall condition). Behavioral variables (resting, locomotion, standing, consummatory, elimination, and stereotypic behavior) were scored every 5 minutes from the recordings and compared between stall conditions. Although several measures changed across days in both stall conditions, stall size did not affect the horses' hay consumption, fecal output, or cortisol concentrations, nor the duration of sternal or lateral recumbency as determined by accelerometer data. However, the duration of walking recorded by the accelerometer different between the 2 stall sizes with horses spending more time walking in the smaller stall (136 ft2). Analysis of video recordings also found no difference in percentage of time spent in sternal or lateral recumbency, rolling, standing, stand resting, walking, eating, or drinking. In conclusion, time budgets, food intake, fecal output, and cortisol concentrations were similar in horses housed in the standard-sized stall (144 ft2) compared with the smaller stall (136 ft2), suggesting that the reduced stall size did not result in observable changes in equine behavior or physiologic welfare indicators compared with the standard-sized stall.