Goats as an osteopenic animal model

A large osteopenic animal model that resembles human osteoporotic changes i s essential for osteoporosis research. This study aimed at establishing a l arge osteopenic animal model in goats. Twenty-five Chinese mountain goats w ere used in which they were either ovariectomized (OVX) and fed with a low- calcium diet (n = 16) or sham-operated (SHAM; n = 9). Monthly photodensitom etric analysis on proximal tibial metaphysis and calcaneus was performed. T wo iliac crest biopsy specimens obtained before and 6 months after OVX were used for bone mineral density (BMD) measurement with peripheral quantitati ve computed tomography (pQCT). Lumbar vertebrae (L2 and L7), humeral heads, and calcanei were collected for BMD measurement after euthanasia. The hume ral heads and calcanei were used in biomechanical indentation test. BMD mea surement showed a significant 25.0% (p = 0.006) decrease in BMD of the ilia c crest biopsy specimens 6 months after OVX. It also was statistically sign ificant when compared with the SHAM (p = 0.028). BMD at L2, L7, calcaneus, and humeral head reduced by 24-33% (p ranged from 0.001 to 0.011) when comp ared with the SHAM. Photodensitometry showed a continuous decrease in bone density after OVX. There were significant decreases of 18.9% in proximal ti bial metaphysis (p = 0.003) and 21.8% in calcaneus (p = 0.023) in the OVX g roup 6 months postoperatively. Indentation test on the humeral head and cal caneus showed a significant decrease 52% (p = 0.006) and 54% (p = 0.001), r espectively, in energy required for displacement of 3 nun in the OVX group compared with the SHAM group. The decreases correlated significantly to the decrease in BMD of the corresponding specimens (r(2) = 0.439 and 0.581; p < 0.001 for both). In conclusion, this study showed that OVX plus a low-cal cium diet could induce significant osteopenia and deterioration of mechanic al properties of the cancellous bone in goats.