Does long-term unilateral circling affect locomotor symmetry in ponies used for carousel rides?

This research investigates whether ponies used for carousel rides develop locomotor asymmetry over time due to the constant circling motion they are subjected to. The study found minor differences in symmetry ratios and asymmetry indices between carousel ponies and a reference group, but found no clear link between these differences and the duration of the pony’s carousel riding career.

Methodology

• Twenty-one ponies used for carousel rides were analyzed. They were made to walk and trot over a pressure plate system to measure various locomotor parameters.
• The parameters measured included the peak vertical force (PVF), the vertical impulse (VI), the stance time (ST), and the hoof contact area (CA).
• The symmetry ratios and asymmetry indices for these parameters were then calculated and compared with reference data. The researchers also took into account any visually evident lameness in their assessments.

Findings

• Most ponies in both the carousel and reference groups exhibited higher loading of the right forelimb while walking and trotting.
• The carousel ponies had slightly lower symmetry ratios and more negative asymmetry indices than the reference group for PVF and VI. There was no significant difference for ST and CA.
• When the analysis was repeated excluding ponies with observable lameness, there were no significant differences in asymmetry indices. However, symmetry ratios in the carousel group were still lower.
• Half of the carousel ponies had trouble lunging in the direction opposite to their usual turning circle, compared to ponies in the reference group who could lunge easily in both directions. The researchers speculate that this is likely due to behavioral conditioning rather than any physical impairments.
• Crucially, the research found no significant link between the duration of the pony’s carousel career and the symmetry indices, suggesting that long-term unilateral circling does not progressively worsen locomotor asymmetry.

Conclusion

• The research found that carousel ponies do exhibit less symmetric locomotion than other ponies, but the difference does not appear to be due to the long-term unilateral circling inherent in carousel work. The differences in lunging behaviour are instead suggested to have a behavioural explanation.
• Based on these findings, the ethical debate surrounding the use of ponies for carousel rides should be informed by the fact that the practice doesn’t seem to induce progressive locomotor asymmetry.