Abstract
Changes in histomorphometric values of iliac trabecular bone and serum biochemical constituents related to bone metabolism in normal beagle dogs during growth were examined. A total of 90 dogs (male; 46, female; 44) aged 3, 6, 9, 12 and 24 months, were used. Each dog was injected with tetracycline hydrochloride and calcein for double bone labeling in order to quantitatively measure dynamic as well as static parameters in bone histomorphometry and a part of the ilium was later removed. The measurements on cancellous bone areas of undecalcified iliac sections were performed with a semiautomatic image analyzer. There were no sex significant differences in histomorphometric values except for mineralization lag time at the age of 3 months. In the static parameters, bone volume and mean trabecular thickness increased from 3 to 9 months of age. Bone surface area and mean osteoid thickness increased up to 6 months. Osteoid volume and osteoid surface area decreased up to 6 months of age. As to the dynamic parameters, the mineral apposition and bone formation rates decreased from 3 to 12 months of age. Mineralization lag time increased from 3 to 9 months of age. However, high bone surface area values in both sexes and low osteoid thickness values in females were seen at the ages of 9 and 12 months. Low values of trabecular thickness in both sexes, osteoid thickness and mineralization lag time in males and mineral apposition rate in females were also noted at the age of 12 months. Serum total calcium did not show any specific tendency. Serum phosphorus, alkaline phosphatase activity and osteocalcin decreased from 3 to 12 or 24 months of age except for the high value of alkaline phosphatase activity at 12 months of age in males. Parathyroid hormone and calcitonin increased from 3 to 9 or 12 months of age. In conclusion, the results indicate that histomorphometric values of iliac trabecular bone and the serum biochemical values reflect alternations in bone metabolism in normal beagle dogs during growth in which change occurs rapidly at 6 or 9 months, and that these changes continue until adulthood is reached at the age of 24 months.
