Thorold's deer has a number of physical and physiological adaptations to its high altitude environment. The short legs and broad hooves make it an agile climber, able to use steep mountainous terrain to escape predators. Their nasal cavities are unusually large, allowing them to breathe in rarified high altitude air, while the thick hair protects against the cold. The red blood cells in this species are smaller than average for similarly sized mammals, and are very numerous, both features that increase its ability to take up limited amounts of oxygen.