SKELETAL CHANGES IN THE OVARIECTOMIZED EWE AND SUBSEQUENT RESPONSE TOTREATMENT WITH 17-BETA ESTRADIOL

The ewe has been suggested as a suitable large animal model for assess ment of therapeutic agents for the treatment of osteoporosis. In this study we asses the response of ewe bone;mineral parameters, using dual energy x ray absorptiometry (DXA), after ovariectomy. Regular DXA ana lysis was performed over a period of 75 weeks followed by a period of dosing with 17 beta oestradiol. Total body bone mineral density (BMD) was reduced in ovariectomised animals 15 weeks post operatively. BMD r emained lower than control animals for the entire pre dose period. Sub sequently, dosing with 17 beta oestradiol prevented further loss of bo ne over a period of 38 weeks. Several complicating factors were noted during the study including seasonal BMD variation, a correlation betwe en fat/lean ratio and total body BMD together with a reversible reduct ion in bone mineral content as a result of lactation. Also changes in BMD were associated with age at ovariectomy.