Agreement between subjective evaluations and a markerless AI-based gait analysis system during lungeing assessment in traditional racehorses

Abstract

Background

Subjective lameness evaluation during lungeing is routinely performed in equine practice, but its consistency remains limited, especially in cases of mild or complex asymmetry.

Aims

This study aimed to assess the agreement between subjective gait evaluations and a markerless AI-based gait analysis system (OAI-MS) in traditional racehorses during lungeing. Intra- and inter-observer agreement of subjective evaluations was also investigated.

Methods

24 traditional racehorses were assessed during routine pre-race inspections (T0) while trotting on a soft surface. Two experienced equine clinicians independently evaluated each horse on both reins using the AAEP 0–5 scale; scores were then converted to a 3-level ordinal scale (0 = sound, 1 = mild, 2 = severe). Simultaneously, gait data were collected using the OAI-MS. A subset of 10 horses was re-evaluated after 10 days (T1) to assess short-term repeatability of the OAI-MS. Video-based reassessment (T2) was used to evaluate intra-observer agreement. Agreement was calculated using weighted Cohen’s and Fleiss’ kappa. p < 0.05.

Results

Inter-observer agreement ranged from κ = –0.20 to 0.36. Agreement between subjective evaluators and the OAI-MS ranged from slight to moderate (κ = 0.13–0.47). Intra-observer agreement was fair (κ ≈ 0.22), and OAI-MS repeatability reached κ = 0.43. Agreement was higher for forelimbs than hindlimbs. Most discrepancies were of low magnitude.

Conclusion

Subjective gait evaluations during lungeing showed limited agreement. The OAI-MS demonstrated moderate repeatability, supporting its usability in the field and its potential role as a complementary tool in clinical decision-making, particularly when asymmetries are mild or disagreement occurs.