The Female Ferret (Mustela Putorius Furo) as an in Vivo Model for Skeletal Research

Estrogen loss-induced bone remodeling and microdamage accumulation may play significant roles in postmenopausal bone fragility. We asked whether the adult female ferret (Mustela putorius furo) is suitable as a small animal model in which to study estrogen loss-induced bone remodeling, and whether the rat ulnar end-load bending model could be adapted to the ferret ulna for the study of microdamage-induced remodeling in cortical bone. To determine whether ovariectomy results in a significant increase in cortical and trabecular bone remodeling in adult female ferret, we ovariectomized 8 female ferrets, while an additional 8 ferrets served as intact controls. All animals were given in vivo bone labels 10 and 3 days pre-euthanasia and were sacrificed 45 days post-ovariectomy. Histomorphometric analysis was performed of the ulna, femoral neck (FN), and secondary lumbar vertebral body (L2), and ulnae were examined for microdamage. To adapt the ulnar end-load bending model for the ferret, we determined the ex vivo mechanical properties of the ferret ulnaradius complex, the ex vivo load-strain relationship in the ulna and radius, and the relative strain magnitudes in the ulna and radius, all of which are required preliminary steps in the development of an in vivo loading protocol. We found that resorption cavity density (rCv.Dn) was 290% greater, activation frequency (Ac.f) was 470% greater, and an bone formation rate (BFR) was 880% greater in ovariectomized than intact, estrous ferret ulnar cortical bone. Ovariectomy did not affect trabecular bone remodeling in the FN or L2. The ulna did not contain any visible microdamage. The maximum load of the intact ulnaradius complex during monotonic loading to failure was 55 N. The load-strain relationship for the ulna and radius were approximately quadratic. Strain was approximately 1 to 8 times greater in the ulna than in the radius depending on the load; as load increased, the ulna experienced more strain relative to the radius. Our data suggest that the female ferret may be useful for the study of estrogen loss-induced cortical bone remodeling and that the end-load bending model may be adapted to the ferret ulna.

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Year

Entry

1970

Yamada H. Strength of Biological Materials. Evans FG, ed. Baltimore, MD: Williams & Wilkins Company; 1970.

1989

Schaffler MB, Radin EL, Burr DB. Mechanical and morphological effects of strain rate on fatigue of compact bone. Bone. 1989;10(3):207-214.

1995

Mackey MS, Stevens ML, Ebert DC, Tressler DL, Combs KS, Lowry CK, Smith PN, McOsker JE. The ferret as a small animal model with BMU-based remodelling for skeletal research. Bone. October 1995;17(4)(suppl):S191-S196.

2000

Vashishth D, Koontz J, Qiu SJ, Lundin-Cannon D, Yeni YN, Schaffler MB, Fyhrie DP. In vivo diffuse damage in human vertebral trabecular bone. Bone. February 2000;26(2):147-152.

1990

Foldes J, Shih M-S, Parfitt AM. Frequency distributions of tetracycline-based measurements: implications for the interpretation of bone formation indices in the absence of double-labeled surfaces. J Bone Miner Res. October 1990;5(10):1063-1067.