Morphological findings in young dogs chronically fed a diet containing excess calcium.

Morphologic findings in Great Dane pups fed a supplement containing three times the recommended calcium content (HC-group) and a diet which followed recommended requirements (NC-group) are described. In the HC-group significant skeletal changes were found using histologic, histomorphometric, and bone labeling techniques. Both cartilage and osseous changes were present. Articular and physeal cartilage changes consisted of various-sized irregularities of retained cartilage with disturbances in enchondral ossification. These changes were comparable to osteochondrotic lesions. Osseous lesions were characterized by retarded maturation and retarded remodeling of trabecular and cortical bone, a higher percentage of total bone volume, and a decreased number of osteoclasts. Initially the parathyroid glands were found to be less active, and in the thyroid glands the C-cells were more numerous. At the end of the study these differences were far less pronounced.