“…The number of animals used in these studies was variable (range: from 20 to 88) and not reported in a few articles ( n = 3) [ 26 , 31 , 38 ]. The main technique used to assess OA was histology, which in some studies was also combined with specific semi-quantitative scores (Mankin’s and Osteoarthritis Research Society International (OARSI)) [ 26 , 33 , 37 , 39 , 40 , 50 ] and/or immunohistochemistry [ 33 , 46 ], ramp test [ 32 ], micro-computed tomography [ 27 , 32 , 46 , 49 , 51 ], anterior drawer test, Magnetic Resonance Imaging [ 47 ], and dual-energy X-ray absorptiometry [ 27 ]. Some articles ( n = 5) were designed to test the changes in the gut microbiota and metabolism during the administration of various supplements, such as quercetin, bioactive compounds from chicken cartilage, extracellular vesicles (EVs) from raw milk, oligofructose and prebiotic fiber, for OA [ 26 , 31 , 32 , 33 , 34 ].…”