Separating young horses from their group and stalling them in individual boxstalls is stressful.
For initial training, horses are often transferred from group housing to individual boxstalls, which is a potential stressor.
In a study conducted in Austria, salivary cortisol concentrations (an indicator of stress), locomotion activity, and heart rate were analyzed in eight 3-year old mares. Mares were transferred abruptly from group paddock housing to individual boxstalls without paddock access. Data were collected for 4 days while mares were in group housing and for 5 days immediately after the change in housing in individual boxstalls.
Once in boxstalls, mares underwent routine equestrian training for young horses. While in group housing, cortisol concentrations showed a diurnal rhythm with values approximately 0.6 ng/ml in the morning and a decrease throughout the day. When horses were moved to boxstalls, cortisol concentrations increased to 1.8 ng/ml within 30 minutes and did not return to baseline values for 6 hours. On the days following the housing change to boxstalls, a cortisol diurnal rhythm was re-established but at a higher level compared to the level found in group housing. Locomotion activity was higher when mares had access to a paddock than when kept in individual boxstalls and heart rate increased for approximately 60 minutes when mares were separated from their group.
This study confirms what was previously thought; separating young horses from their group and stalling them in individual boxstalls is perceived as stressful.