Garvican ER, Vaughan-Thomas A, Innes JF, Clegg PD. Musculoskeletal Research Group, School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral CH64 7TE, UK. Vet J 2010 Jul 185 1 36-42 Abstract Type II collagen is a major component of articular cartilage and its breakdown is a key feature of osteoarthritis. Products of cartilage collagen metabolism can be detected in the blood, synovial fluid and urine. Several biomarker assays have been developed which can be used to measure the synthesis and degradation of collagen, and therefore provide information regarding cartilage turnover. This is the first part of a two-part review and describes the need for accurate, reliable information regarding collagen turnover, the processes by which the biomarker epitopes are generated, their application to the study of both healthy and diseased cartilage and the results of currently published studies, with particular reference to the veterinary species. The second part of the review considers the non-collagenous biomarkers of cartilage matrix turnover. Copyright © 2010 Elsevier Ltd. All rights reserved.