Alaskan Malamute chondrodysplasia III. Connective tissue of bone

The dwarf Alaskan Malamute was compared in these studies with normal Alaskan Malamutes of the same age with regard to collagen and mucopolysaccharide components of the bone. The hydroxyproline concentration of bone segments was normal in most instances, whereas, the hexosamine concentration was increased (P less than .05) in distal segments. Alterations in amounts of collagen soluble in neutral salt, dilute acid and 5 M guanidine hydrochloride were observed and these were related to changes in subunits found following chromatography on carboxymethyl (CM) cellulose. The presence of an increased keratosulfate fraction in dwarf Alaskan Malamutes was consistent with an apparent delayed bone ossification process. These changes in the connective tissue moieties may account for the gross morphology with respect to the bowed legs. The primary cause for these changes has not yet been determined but alterations in factors related to processes of normal development in bone are suggested. The present observations tend to support the hypothesis that the changes in the bone are secondary to some other primary metabolic defect.