What characteristic of reptilian skin makes subcutaneous fluid administration more challenging than in mammals?

The characteristic of reptilian skin that makes subcutaneous fluid administration more challenging than in mammals is inelasticity. Reptilian skin is less flexible compared to mammalian skin, which can pose difficulties when attempting to create adequate space for fluid administration beneath the surface. This inelasticity can lead to less effective absorption of the fluid because, unlike in mammals where the skin can stretch and accommodate the fluid more easily, reptilian skin remains rigid and may not allow for the same diffusion and distribution of fluids.

While the other characteristics mentioned, such as thickness and the presence of scales, do influence the overall structure and function of reptilian skin, it is the inelasticity that specifically hinders the process of administering fluids subcutaneously. High permeability doesn’t apply here either, as reptilian skin tends to be less permeable to substances than that of mammals, making it challenging not only for fluid delivery but also for drug absorption. Thus, inelasticity stands out as the key factor in complicating fluid administration in reptiles.