Osteoporosis is characterised by bone loss and deterioration of bone tissue. Globally, postmenopausal osteoporosis is considered a significant health burden in women. Animal models that resemble human postmenopausal bone loss may be used in an attempt to discover novel biomarkers of disease and provide information on possible new treatments. The aim of this study was to validate the combination of ovariectomy and glucocorticoid treatment in sheep as a large animal model for osteoporosis by measuring the level of specific biomarkers in the blood of the sheep and measuring bone loss over 5 months. Merino ewes (28) were randomly allocated into four groups: control, ovariectomised (OVX), and two OVX group receiving glucocorticoids, one group once monthly for 5 months (OVXG 5M) the other for 2 months followed by no treatment for 3 months (OVXG 2M). Blood samples were collected at baseline, 2 months and 5 months, and bone resorption marker serum C-terminal telopeptides of type I collagen (CTX-1) concentration and bone turnover marker serum osteocalcin (OC) concentration were measured. Bone mineral density (BMD) of lumbar spine and femur were measured by dual-energy X-ray absorptiometry (DXA) scans. CTX-1 and OC did not significantly differ (P>0.05) by treatment group. On the other hand, at 5 months, compared to controls, lumbar spine BMD was reduced by 7% (P<0.05), 28% (P<0.001) and 12.7% (P<0.10), and femur BMD was reduced by 10.6% (P<0.05), 21.0% (P<0.001) and 6.4% (P>0.05), in the OVX, OVX 5M, and OVX 2M groups respectively. Therefore, bone was lost in the lumbar spine and femur due to oestrogen deficiency (OVX sheep) and exacerbated by glucocorticoid treatment. This supports the use of the sheep model as a short-term animal model for postmenopausal osteoporosis.