Aim of the study The molecular aspects of inflammation were investigated in equine articular cartilage explants using quantitative proteomics. Material and Methods Articular cartilage explants were stimulated with interleukin (IL)-1β in vitro for 25 days, and proteins released into cell culture media were chemically labelled with isobaric mass tags and analysed by liquid chromatography-tandem mass spectrometry. Results A total of 127 proteins were identified and quantified in media from explants. IL-1β-stimulation resulted in an abundance of proteins related to inflammation, including matrix metalloproteinases, acute phase proteins, complement components and IL-6. Extracellular matrix (ECM) molecules were released at different time points and fragmentation of aggrecan and cartilage oligomeric matrix protein was observed at days 3 and 6, similar to early-stage OA in vivo. Degradation products of the collagenous network were observed at days 18 and 22, similar to late-stage OA. Conclusion This model displays a longitudinal quantification of released molecules from the ECM of articular cartilage. Identification of dynamic changes of extra cellular matrix molecules in the secretome of equine explants stimulated with IL-1β over time may be useful for identifying components released at different time points during the spontaneous OA process.