Unless she needed to be on a drip she is better off at home with you, especially if your practice isn't manned overnight. Poor dog, just keep going with the rehydration and take her back in the morning. The fact that she is vaccinated means that she will be mounting a really good immune response to the virus pretty soon - vaccination doesn't always mean 100% immunity but she will still benifit from it as she will have some anti-bodies already working in her blood stream. Obviously if he becomes super lethargic or starts to look pale (you can look at her gums or the pink bit in her eyes - just gently pull down) then call an emergency vet otherwise just take her back for a check up tomorrow, im sure she'll be fine.
Thanks for replying, I slept with her last night by pulling the crap leather sofa right up by the baby gate to the kitchen and will be doing the same tonight so I can keep an eye on her. She has had almost all of the rehydration sachets so that's got to be good. Will keep on giving her water when she has finished that.
Glad it will help that she has been vaccinated - I was really ignorant and had no idea this could happen with dogs who were up to date with jabs. Have let my friends with dogs know as she could have passed it on during incubation. Horrible