There are a lot of vets that will see a reptile and a lot of them are behind the times on what they know. While there may be some fluid absorbed thru the vent, it will be minute and not enough to hydrate a dehydrated animal. Its basically a matter of common sense. If fluids go thru one way they will go back out the same way. For an arid country animal this would mean that all their body moisture would be exiting the vent! Equaling a bunch of dead dried up animals!