i had a pup with parvo, i kept him hydrated as best i could orally, but also gave him shots of sterile water just under the skin between his shoulders. it makes a pocket of water under the skin that his body will absorbe. there is a name for doing that, but i cant remember what it is. the size of the pocket depends on the size of the dog. my pup was about 3lbs so i gave him one about half the size of a baseball or a little smaller. if you've never done it, you may want to let your vet do it and watch how. hope that helps.
it's called giving 'subcutaneous fluids', there is plenty of info about it online, just google it.
http://www.valleyvet.com/ct_detail.html?pgguid=30e079fb-7b6a-11d5-a192-00b0d0204ae5http://www.atlanticmedsupply.com/shopdisplayproducts.asp?id=243&cat=IV+Solutions
