The aim of this study was to realistically simulate density growth in the equine 3rd metacarpal bone (MCIII), the most frequently fractured lower limb bone in the Racehorse. A well-established open system thermodynamics approach was adopted into a hierarchical approximation framework. This allowed for an efficient construction of multigrid iterative solvers and solving large problems in 3D including entire bones with their complicated structure. The coupled nonlinear governing equations of mass and linear momentum conservation were implemented in finite element code MOFEM, where tangent stiffness matrix was acquired automatically by using ADOL-C library. Its performance was demonstrated with classical benchmark problems. In order to accurately represent geometry, the final numerical model of the equine bone was generated by processing CT scan images. Furthermore, simplified boundary conditions corresponding to peak forces at mid-stance of a gallop were applied to the bone surface. The obtained density pattern was validated by comparison with the CT scanning data from a cadaver racehorse metacarpal bone. It was shown that the method has the potential to accurately model the effect of loading on bone and could be applied to future studies in order to prevent fatal injuries.