You actualy aren't supposed to take food away from rabbits before surgery. your vet must just be treating her as if she were a dog or a cat but it's actualy not good for them to have the food held off, due to the way they digest if they get empty it can mess things up. I can't find a good site explaining it well. Sorry I didn't see this yesterday. Sounds like she's going to be fine now but I'd find another vet with bunny knowlage for the future.

http://www.willasark.com/rabbittriage.cfm
If you are bringing your bun in for neutering or spaying and they tell you to with hold food and water before the operation, then find another vet. Bunnies cannot vomit, so there is no need to with hold food and water A good vet will know this, and it may cause the bunny problems to go with out food anyway.

http://www.bestfriends.org/theanimal...bbithealth.pdf
Surgery Contrary to the procedure with other animals, food and water should not be withheld from a rabbit the evening before surgery, but should be taken away the morning of surgery. If the veterinary office staff directs you to withhold food the night before, discuss the request with your vet. Generally, the reason that food is withheld from cats and dogs is the possibility of vomiting during surgery, but rabbits cannot throw up, so it’s not a danger with rabbits. Withholding food and water is harmful to rabbits and causes a longer recovery time from surgery.
To assist with the recovery process, as soon as the rabbit awakens from surgery, he should be encouraged to eat. After surgery, to help the bunny begin eating again, offer him a variety of his favorite fresh foods.


http://www.rabbit.org/chapters/san-diego/faq/
Q. Do I have to fast my rabbit before surgery?
A.
No, it is not necessary to have your rabbit fast (withhold food) prior to surgery or anesthetic procedures. Because rabbits cannot vomit, the risk for aspiration of food into the lungs is not as great as for cats, dogs, or humans. If your rabbit is going in for oral or dental procedures, however, it is a good idea to refrain from feeding him for up to two hours prior to the procedure to prevent any food particles from blocking the view of the mouth or oral cavity.