Efficacy and welfare effects of different forms of physical restraint for upper airway endoscopy of horses.

Background: Physical restraint of horses for veterinary procedures is necessary to allow completion of tasks effectively and without injury to patient or personnel.

Objectives: To compare physiological effects and behavioural responses to four commonly used restraint techniques for upper respiratory tract (URT) endoscopy in unsedated horses.

Study design: Blocked and randomised interventional study.

Methods: Twelve university owned teaching horses were blocked into groups of four and randomly allocated to one of four restraint methods (nose twitch, ear hold, Stableizer® and nil restraint) for URT endoscopy. Horse response to restraint and endoscopy was evaluated subjectively and by objective measures of procedural efficacy (duration and head movement), time domain indices of heart rate variability (HRV), saliva cortisol and plasma β-endorphin concentrations.

Results: Horses demonstrated strong individual differences for procedure tolerance and preferred method of restraint, but there were no differences observed in outcome measures related to procedural efficacy or neuroendocrine response associated with restraint type. Repetition of experimental procedures was associated with a progressive decrease in mean (95% CI) minimum heart rate from 34.2 (31.7-36.7) to 30.1 (28.0-32.2) bpm (p < 0.001), and increased HRV measures related to parasympathetic dominance. Cortisol was greatest on Day 2 (1.5, 1.1-2.5 nmol/L; median, 95% CI), compared with Day 1 (0.8, 0.5-1.6 nmol/L; p = 0.02).

Main limitations: Convenience sample of horses familiar with most study interventions; intervention was minimally invasive and of short duration.

Conclusions: Study findings did not support current recommendations to prioritise one type of restraint over other available techniques.