Horses that have a BFS (including SAO [ie, osteoporosis associated with pulmonary silicosis]) may have deformities in multiple bones (eg, scapulae and pelvic bones), osteoarthrosis of cervical vertebrae, nondisplaced rib fractures, or complete displaced fractures of bones (eg, pelvic bones).1–3 Clinically affected horses most commonly develop nonspecific lameness, deformities (ie, bowing) of scapulae, and, in severely affected horses, lordosis.3 Treatment is primarily palliative, and the most severely affected horses die or are euthanized for humane reasons because of catastrophic fractures. The etiology of this BFS is unknown; however, most affected horses have concurrent pulmonary silicosis associated with a history of exposure to soil containing silicon dioxide, which is cytotoxic.3
Bone tissue from horses with severe SAO is qualitatively characterized by a mosaic of reversal lines and large osteoclasts with high numbers of nuclei.2 To the authors' knowledge, the morphological and functional effects of such characteristics on the biological and mechanical properties of bone are unknown. The purpose of the study reported here was to determine the effects of a BFS on morphological and mechanical variables of trabecular bone tissue samples collected from bones (ie, third metacarpal bones) that do not typically develop clinically detectable abnormalities in affected horses. We hypothesized that the morphological and mechanical properties of trabecular bone samples collected from third metacarpal bones of cadavers of horses with a BFS would be different than those of trabecular bone samples obtained from cadavers of horses without a BFS and that affected horses would have weaker trabecular bone versus unaffected horses. In addition, we hypothesized that differences in bone tissue strength would be related to differences in the quantity and amount of bone mineralization. Findings of the study reported here were expected to enhance understanding of the pathogenesis of BFS.
Bone fragility syndrome
Strain energy density
Butcher Boy Bandsaw, American Meat Equipment LLC, Selmer, Tenn.
Model 102065, Starlite Industries Inc, Rosemont, Pa.
Model J-2530, JET, La Vergne, Tenn.
IsoMet low speed saw, Buehler, Evanston, Ill.
Faxitron Series 43805 X-ray System, Hewlett Packard Corp, Buffalo Grove, Ill.
Kodak Oncology Film, Carestream Health Inc, Rochester, NY.
μCT 35, Scanco Medical AG, Basserdorf, Switzerland.
RAND function, Microsoft Office Excel, Microsoft Corp, Redmond, Wash.
All Purpose Instant Krazy Glue, Krazy Glue, Columbus, Ohio.
Model 809 and Testware SX software, MTS Systems Corp, Minneapolis, Minn.
Model 662.20C-04, MTS Systems Corp, Minneapolis, Minn.
MATLAB, version 2011a, MathWorks, Natick, Mass.
Proc GLM, SAS, version 9.2, SAS Institute Inc, Cary, NC.
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