Effects of Overcheck Use on Stress Parameters and Welfare Implications in Driving Horses.

Three sequential studies were performed to evaluate the effects of tying horses while wearing overchecks (strap from the bridle to backpad). In an observational study, horses (n = 305) wore high (HC), low (LC), or no overchecks (NC) with frequencies of 29.2%, 51.8% and 19.0% respectively. Study 1 (Latin square, n = 6) consisted of a 90-min tie test (90TT) with treatments (HC, LC, NC) x periods (1-3). Horses wearing HC had higher plasma cortisol (P < 0.01) when compared to LC and NC. Muscle soreness (MSS) and tightness (MTS) were evaluated pre and 24 hr post 90TT and were higher (P < 0.01) 24 hrs after 90TT regardless of treatment. In study 2, in order to determine if acclimation to tying with overchecks could reduce the cortisol response in study 1, horses (n = 6) were tied 60 minutes/day for 2 weeks followed by a 60-min TT (60TT). Neither plasma cortisol nor heart rate were elevated above baseline levels, suggesting adaptation to novel stressors. Tying with restrictive HC appears to be a stressor, which may be reduced if an adaptation period is provided.