CONCLUSION

This study systematically evaluated hand-pour fabricated fiber-reinforced E and R composites together with PU foam to identify an affordable material combination for canine CBM fabrication. Among the formulations evaluated, E+3%RF provided the most favorable overall balance of mechanical performance, manufacturing reproducibility, and casting feasibility. Fiber reinforcement significantly increased the elastic modulus and yield strength of epoxy composites while reducing ultimate stress and ultimate strain, producing mechanical behavior that more closely approximated canine cortical bone than unreinforced E. In contrast, R showed no significant improvement in elastic modulus across the tested fiber weight fractions, most likely because cure shrinkage limited efficient fiber-matrix load transfer. The PU foam exhibited an apparent density and elastic modulus consistent with the lower end of the reported canine trabecular bone spectrum, providing a mechanically distinct cancellous component suitable for incorporation into a bilayer construct.

From a practical perspective, the proposed E+3%RF cortical shell combined with a PU foam cancellous core offers a simple, low-cost, and locally manufacturable alternative for developing canine orthopedic training models. The estimated raw material cost of approximately USD 1.90 per model, representing about 7% of the cost of a comparable commercial model, demonstrates the potential to substantially reduce training expenses while improving accessibility for veterinary institutions, particularly in resource-limited settings. The low coefficient of variation observed for E+3%RF further supports its suitability for standardized batch production using a hand-pour fabrication process.

A major strength of this study is the systematic comparison of Eand R systems across multiple fiber weight fractions using standardized mechanical testing, thereby providing the first evidence-based optimization of fiber reinforcement specifically for canine orthopedic training model fabrication. However, the study was limited to quasi-static uniaxial tensile characterization, and the proposed composite system has not yet been validated under clinically relevant loading conditions such as compression, bending, torsion, drilling, or screw fixation. In addition, the mechanical performance of the integrated bilayer construct remains to be established.

Future studies should evaluate the complete hybrid CBM under functional orthopedic procedures, optimize the cancellous core architecture to better reproduce canine trabecular bone, investigate alternative reinforcement strategies to further improve cortical stiffness, and compare training outcomes between the proposed synthetic model and cadaveric specimens. Such investigations will determine whether this affordable composite platform can serve as a reliable substitute for cadaveric bone in veterinary surgical education and contribute to implementation of the 3Rs principle through reduced dependence on animal-derived teaching materials.