The normal variation in structure and composition of canine hip articular cartilage proteoglycans.

The composition of the weight bearing portion of the femoral head articular cartilage from both sides of greyhounds 11-32 months of age was studied with regard to variability of proteoglycans. Extractability of proteoglycans was very similar for all samples. Other parameters, i.e. contents of proteoglycans in the cartilage, hyaluronic acid content of the proteoglycan fraction, as well as contents of keratan sulfate and chondroitin sulfate, size of proteoglycans and ability of proteoglycans to aggregate with hyaluronic acid, were similar in samples from the right and left side of each dog. The variability from one dog to another was large and not related to age. The data show that in experimental studies of joint disease the contralateral joint can be used as a control to a treated joint, while the large interindividual variability makes comparison difficult between individuals.