## 3 Results  
### General Results  
The search strategy identified a total of 200 articles across three major databases: PubMed (n = 53), SCOPUS (n = 77), and Web of Science (n = 70). Following removal of 112 duplicate records, we retained 91 unique articles for preliminary screening. Through a rigorous evaluation of titles, abstracts, and keywords, we excluded 63 articles based on the following criteria: (1) irrelevant population--studies focusing on non-equine species or non-musculoskeletal conditions (e.g., human tendon injuries) and (2) intervention mismatch--investigations of therapies other than PRP (e.g., stem cell-only treatments). After a full-text review of the remaining 28 articles, we ultimately included 22 studies that met all eligibility criteria (Figure 1). The six articles excluded from the review were three articles that evaluated the effect of platelet lysates [32; 33], one study that used a PRP kit to concentrate a bone marrow aspirate [34], and two studies had insufficient information [35; 36]. Of the twenty-two selected records, five case series [17; 18; 37; 38; 39] evaluated the effects of PRP on horses with tendonopathies and desmopathies (Table 1). Four case series [40; 41; 42; 43] evaluated PRP in combination with mesenchymal stem cells, bone marrow, or bone marrow mononuclear cells under similar conditions (Table 2). Additionally, four randomized clinical trials [44; 45; 46; 47] evaluated PRP either alone or in combination with other therapies for tendonopathies and desmopathies (Table 3). Seven controlled experimental studies [48; 49; 50; 51; 52; 53; 54] investigated the effects of PRP on these conditions (Table 4), while two experimental studies [55; 56] assessed PRP in combination with mesenchymal stem cell therapies (Table 5). Overall, no severe adverse effects were reported in the evaluated studies. The included studies varied widely in sample size, ranging from small case series (e.g., five horses in Arguelles  
Figure 1: Flowchart of the study selection process according to [PERSON]. et al. [18]) to larger clinical trials (e.g., one hundred horses in [PERSON] et al. [46]). Notably, 12/22 studies (54.5%) had sample sizes \(\leq\) 10 horses, while only 4/22 (18.2%) included \(\geq\)50 horses. The diagnosis and evolution of the tendon and ligament lesions were performed by a subjective lameness examination and US evaluation. These diagnostic approaches were mainly used in two case series [18; 37] and three clinical trials [44; 45; 47]. Conversely, a lameness evaluation was not a primary diagnostic tool in most experimental models of induced lesions surgically or with collagenase prior to PRP application [48; 49; 50; 51; 52; 53; 54]. In general, a US evaluation was combined with a clinical lameness assessment to correlate structural and functional improvements. All studies used a US evaluation to confirm and monitor tendon and ligament healing. High-frequency US imaging was used for lesion size measurements [39; 42] and assessments of collagen fiber organization [50; 51]. The monitoring of neovascularization was performed by color Doppler US (CDUS) [49]. Histologic and molecular diagnostic methods were used primarily in most experimental models of surgically or collagenase-induced lesions prior to PRP application to assess tissue remodeling at the cellular level. Histology was used to evaluate the collagen fiber orientation and density [52; 54], fibroblast proliferation, and matrix remodeling [55; 56]. Furthermore, immunohistochemistry for Factor VIII was used to assess vascularization and endothelial activity [48; 54], while a gene expression analysis (COL1A1, tenascin, and MMPs) was performed to assess neurogenic differentiation and tissue regeneration potential [56]. In studies where PRP was used as the sole clinical treatment, improvements were observed in lameness, ultrasound (US) appearance, and return-to-competition times [17; 18; 37; 38; 39].