Some of the effects of the semi-synthetic glycosaminoglycan polysulfuric acid ester (GAGPE) were investigated on the osteoarthritis-like lesions in the Pond-Nuki dog model, in respect to histological grade of anatomical lesions, collagenolytic enzyme activity, and a parameter of collagen network integrity. Prophylactic treatment by intra-articular injections twice weekly for 4 weeks caused amelioration of canine cartilage erosions. Preliminary evidence for suppression of collagenolytic enzyme activity, as well as protection of a tight collagen network studied in the canine cartilage was obtained.