This was taken from the "Gecko's Mali Uromastyx Care Sheet"
The same camn be applied to other lizard species as well.
Output · Things which come out of a Uromastyx · Granted, these things may also come out of other lizards, but we're talking about uros here! Here is a list of what happens when your uro arches his tail in that special way. (This section based on information submitted by Jason Mottern.)
Clear Water · Reptile kidneys are incapable of producing hyperosmotic (simplified, salty) urine like in mammals. That's why excess hydration is expelled as clear water.
Feces · You know it, you love it. It's one of the reasons why uro care isn't nearly as difficult for the "sensitive of nose" as, oh, dogs or cats.
The yellowish white stuff · Nitrogenous wastes are excreted as an insoluble salt and uric acid at the end.
If you see anything else coming out of your uro, such as blood or worms, get it to a vet or someone very experienced in uromastyx care immediately! The Uromastyx Mailing List is a great source of information, as well, but if you count on me as your only online source of emergency uromastyx care, you will be sorely disappointed and I take no personal responsibility for your inaction.
-----
**Kenn**