Tissue Engineered Vascular Grafts (TEVGs) may be grown in living pigs to further their development towards use in humans to repair damaged aorta. To explore whether porcine grown TEVGs are good models for human grown TEVGs, normal human and porcine aortic tissues are loaded in shear deformation to compare the differences in the dissection response of these viscoelastic tissues. Shear is strongly related to aortic dissection. Translational constant rate and sinusoidal shear deformation tests characterize dynamic mechanical properties of aortic tissue. Knowledge of the tissue microstructure helps determine the effect of interstitial fluid-solid interaction on the shear response of the specimens. Transient and quasi-periodic response characteristics provide baseline material properties of normal porcine aortic tissue to compare its dissection resistance with TEVG porcine aortic tissue. The results show that normal porcine aortic tissue is sufficiently similar to human aortic tissue to justify the continued development of porcine grown TEVG models.