Extensive degeneration of articular cartilage (AC) is a primary event in the pathogenesis of osteoarthritis (OA) and other types of joint and bone inflammation. OA results in the loss of joint function, usually accompanied by severe pain, and are the most common type of arthritis, affecting more than 10% of adults. The characteristic signs of OA are progressive cartilage destruction and, eventually, complete loss of chondrocytes. A key enzyme responsible for these degenerative changes in cartilage is matrix metalloproteinase-13 (MMP-13), which is thought to be a major contributor to the degenerative process occurring during OA pathogenesis. The aim of the present review is to shed light on the general role of MMPs, with special emphasis on MMP-13, in the induction of OA and the general basis of OA treatment. The pathogenic mechanism of this highly prevalent disease is not clear, and no effective disease-modifying treatment is currently available. Any updated information about OA treatment in human patients will also benefit companion animals such as horses and dogs, which also suffer from OA. Selective inhibition of MMP-13 seems to be an attractive therapeutic strategy.