Abstract
Osteoarthritis (OA) is a major cause of equine lameness, with few effective disease-modifying treatments. This systematic review, conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, evaluated the efficacy of platelet-rich plasma (PRP) for equine OA by analyzing 11 studies (6 clinical, 5 experimental) identified through Web of Science, Scopus, and PubMed (2000-2024). The screening process identified 252 records, of which 136 were duplicates and 105 were excluded based on predefined criteria. The analysis showed that intra-articular PRP injections are generally safe, with transient synovial inflammation occurring mainly when PRP was activated with bovine thrombin. Both leukocyte-rich (L-PRP) and leukocyte-poor (P-PRP) formulations exhibited comparable efficacy, though optimal platelet concentrations (423-658 × 10(3)/μL) and dosing regimens remain undefined. A PRISMA-based quality assessment highlighted substantial variability in study design, with clinical trials constrained by small sample sizes and high risk of bias. Experimental studies confirmed PRP's biological activity but showed inconsistencies in preparation methods. The findings indicate that PRP activation is unnecessary and may even be pro-inflammatory, that multiple injections could improve outcomes, and that reporting of cellular composition is inconsistent across studies. The PRISMA framework identified critical evidence gaps, particularly regarding long-term efficacy and protocol standardization. These results emphasize the need for PRISMA-compliant randomized controlled trials featuring standardized PRP protocols, validated outcome measures, and extended follow-up periods to establish evidence-based guidelines for managing equine OA.