Effect of Pen Size on Stress Responses of Stall-Housed Horses

An interesting study that suggests a minimum turn out size of 3680 sq ft per horse for management systems that use limited turn out for multiple horses. This size minimized stress and aggression compared with smaller turn out areas. That would be about 60 by 60 ft per horse. When it comes to horse turn out larger is certainly better, but these researchers found this size to be acceptable among horses accustomed to group turn out.
DrO

Effect of Pen Size on Stress Responses of Stall-Housed Horses Receiving One Hour of Daily Turnout
J Equine Vet Sci. 2021 Mar;98:103366.

Authors
Jessica K Suagee-Bedore 1 , Daniel R Linden 2 , Karen Bennett-Wimbush 2
Affiliations

1 The Ohio State ATI, Wooster, OH. Electronic address: jsb071@shsu.edu.
2 The Ohio State ATI, Wooster, OH.

Abstract
Group turnout provides important socializing opportunities for horses, particularly those that are primarily stalled. A high percentage of equine injuries occur during group turnout, which could partly be due to the physical constraints of fencing. To investigate appropriate paddock sizes for group turnouts, horses (n = 12) from a single herd were divided into groups of 4, stalled for 24 hours, and then turned out for 1 hour into one of three differently sized pens: 342, 263, and 184 m2 per horse. Groups rotated through pens across 3 days, receiving one treatment per day. Blood was sampled for cortisol concentrations at 08:00 hours each morning, and then at 15 and 60 minutes into the turn out sessions, and 60 minutes after return to individual stalls. Groups rotated through three turnout times: 09:00, 12:00, 14:00 hours. Counts of agonistic behaviors (chasing, contact biting, and kicking) and low-level threats (pinned ears, tail swishing, bite and kick threats) were recorded. When turned out in pens that provided 342 m2 per horse, horses exhibited reduced plasma cortisol concentrations by 15 minutes after turnout and at 1 hour after return to their stalls (P < .05). Horses in pens providing 184 m2 per horse exhibited greater agonistic (P < .001) and low-level threat (P < .01) behaviors than horses in larger pens. These data provide insight into appropriate pen sizes for horses from established herds. Providing at least 342 m2 per horse may reduce the chance of injury in horses accustomed to group turnout.