Intra-articular triamcinolone acetonide on front limb symmetry in healthy horses: A quantitative assessment

Abstract

Repetitive concussive forces on joints during exercise may lead to increased inflammation and gait asymmetry. While used to reduce inflammation and symptoms related to joint disease, intra-articular corticosteroids have not been investigated to mitigate subclinical gait asymmetries related to exercise in young horses. This study aimed to investigate the effects of 2 concentrations of triamcinolone acetonide (TA) on front limb gait symmetry hypothesizing that the higher concentration of TA would mitigate exercise-related development of asymmetry. Twenty-four 2-yr-old Quarter Horses, free of clinical signs of gait asymmetry, were stratified by age (827 ± 4 d), BW (412 ± 4 kg), and sex (12 fillies, 12 geldings), and randomly assigned to one of 3 treatment groups for a 56-d study. Each horse received a single intra-articular injection in a randomly selected radial carpal joint of either: 0 mg TA (control, CON; n = 8), 6 mg TA (TA6; n = 8), or 12 mg TA (TA12; n = 8). Horses were housed in individual stalls with runs and were exercised 5 d/wk up to 45 min/d in a progressive workload using a freestall exerciser, beginning 10 d after TA administration. Lameness assessments were conducted at d 0 (pre-injection) and at 1, 2, 3, 7, 14, 28, and 56 d post-injection. For each assessment, horses were trotted in hand over 40 m, twice. Video recordings were analyzed using computer vision via artificial intelligence (Sleip AI). Data were analyzed using the MIXED procedure in SAS, with treatment and day as fixed effects, horse as a random effect, and d 0 values as a covariate. Throughout the study, horses showed no clinical signs of asymmetry, and no differences were detected in gait symmetry of the control group (P > 0.47). There was no main effect of treatment; however, within treatment, a time effect was observed. Gait asymmetry in TA6 decreased (P ≤ 0.03) on d 2 through d 28 compared with d 0 for the push-off phase with no differences in the impact phase. Conversely, gait asymmetry increased (P < 0.04) in TA12 for the impact phase on d 28 and 56 compared with d 0. Additionally, asymmetric movement was lower (P ≤ 0.03) for the push-off phase at d 14 for TA6 compared with TA12. Statistically, changes in gait symmetry were detected; however, these differences, measured in millimeters, may not have physiological significance. Contrary to our hypothesis, the higher concentration of TA did not mitigate the exercise-induced development of asymmetry. These results suggest that the lower TA concentration may be more effective in preventing or reducing gait asymmetry associated with exercise.