Hyaluronic acid with or without triamcinolone acetonide to treat osteoarthritis in treadmill-exercised horses: clinical results and synovial biomarkers

ABSTRACT: Osteoarthritis (OA) often afflicts athletic horses, causing pain, decreased performance, and early exclusion from competitions. Although, no treatment is effective for OA, corticosteroids are a widely used intra-articular therapy, but they may cause progression or acceleration of the disease. The combination of hyaluronic acid (HA) and triamcinolone acetonide (TA) may be more beneficial than TA alone. This study evaluated the effect of treatment with HA, associated or not with TA, on the evolution of surgically induced metacarpophalangeal OA in horses exercised on a high-speed treadmill. In addition, we studied the effect of intra-articular administration of TA on the metabolism of healthy metacarpophalangeal joints. Eight mares without joint pathology were studied. The left fetlock joints were subjected to experimental OA induction and after six months received intra-articular injection of TA and HA (Induced Treated Group, ITG, n = 4) or HA alone (Induced Control Group, ICG, n = 4). The contralateral right fetlock joints were divided into the Treated Group (TG, n = 4), which received TA, and the Control Group (CG, n = 4), which did not receive treatment. After intra-articular treatments the mares were regularly exercised on a treadmill. Three treatments were performed at 60-day intervals (T0, T1 and T2), and the final evaluation of the study was performed at 180 days (T3). Visual lameness was assessed on a scale from 0 to 10 at T0, T1, T2, and T3, when the fetlock goniometry and synovial biomarkers CTX-II and PGE2 were also measured by immunoassay, as were glycosaminoglycans (HA and CS) by agarose gel electrophoresis and densitometry. Analysis of variance was performed in R 4.0.4 software to compare the data (cutoff: P < 0.05). The ITG legs were more lame than the CG at T0 (P = 0.028), T1 (P = 0.023), T2 (P = 0.027), and T3 (P = 0.021), and the goniometry of the ITG was greater (less flexion) at T3 (P = 0.049) than it was in the ICG and higher at T2 (P = 0.016) and T3 (P = 0.008) than in the TG. The TG had a lower angle (more flexion) than the CG at T3 (P = 0.044), and the CG had an increasing goniometry (less flexion) over time (T2 P = 0.001, T3 p=0.005). There were no changes in synovial biomarkers during the experiment. TA + HA therapy had no clinical benefit or related to joint metabolism in the treatment of induced chronic OA under treadmill exercise, and the treatments used did not detectably alter joint metabolism.