TGFB1 and Cowden disease: The aim of the study was to measure SF concentrations of the anti-inflammatory mediator interleukin-1 receptor antagonist (IL-1ra), the anabolic growth factors platelet-derived growth factor BB (PDGF-BB) and transforming growth factor beta-1 (TGF-β1) and the pro-inflammatory cytokine tumour necrosis factor alpha (TNF-α) before and after surgically induced cartilage defect (CD) in healthy horses.