The type of collagen made by the articular cartilage in joints of dogs with degenerative joint disease.

The collagen in the degenerated articular cartilage from dysplastic canine hip joints was characterized as to type by examining cartilage directly and also after labeling cartilage slices with 14C-proline in vitro. Collagen analysis was by sodium dodecylsulfate-polyacrylamide gel electrophoresis of 14C-labeled collagen, and of 14C-peptides which had been cleaved by cyanogen bromide. Amino acid analysis was done on hydrolysates of whole cartilage and of purified collagens to quantify the ratio of hydroxyproline to hydroxylysine. Data revealed that type II collagen was the radiolabeled product synthesized in all samples of degenerated cartilage and was the only collagen detected in biochemical tests in the cartilage of joints with degenerative joint disease as well as in disease free hip joints. Results suggested that chondrocytes in degenerated cartilage of canine joints did not switch their collagen phenotype, but continued to synthesize type II collagen. Cartilage degeneration in joints of dogs with hip dysplasia proceeded without a change in collagen phenotype.