[Effect of long term treatment with prednisone on remodeling of cancellous and cortical bone in dogs].

The effect of 7 month prednisone administration on cancellous and compact bone remodeling in dogs was evaluated by means of histomorphometric and tetracycline labeling methods. It was found that treatment with prednisone resulted in decrease of bone mass which was caused by increased bone resorption as well as considerable diminution of bone formation. In the iliac bone those were manifested by increase in resorption of trabecular surface, decrease in osteoid surface, and reduction in the osteoid thickness, indicating, with a simultaneous decrease in mineralization rate, slowing down of the appositional rate of newly formed bone tissue. In the rib cortical bone treatment with prednisone resulted in increase of the resorption sites together with decrease of the formation sites and tetracycline-labeled osteons. Reduction in the osteoid thickness as well as in the mineralization rate was also observed. The changes of bone remodeling parameters due to prednisone, although proceeding in the same direction in both types of bone tissue, were more marked in the spongy bone than in the compact bone.