When all else fails...do research on renal absorbtion of water.

Of course, the child would just about have to be comatose to allow an enema...I know my three year old would definitely put up a fight.

It's a viable alternative to IV therapy. Luckily, I have the training and means to do both--but I'd be hard pressed to put a catheter in a toddler without doing it everyday. So, my (last resort) plan is to use the drip set as an enema.
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Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein