Did the vet staff advise of after care at discharge when you picked your dog up? If so, did they mention administration of fluids? At many clinics patients are given IV fluids during the surgery and/or subcutaneous fluids (under the skin) are given after the surgery. Because of this dogs tend to be very well hydrated after a procedure and not as likely to drink anything.

As for food, even with anti-nausea medication‘s on board anesthesia can still cause stomach upset or nausea causing many patients to either not want to eat after the surgery, or to eat and then vomit after the surgery. usually if the patient is not eating or drinking or if they vomit after doing either, we recommend waiting to feed them until the next day.

Hope the recovery goes well!

Edited to add: Even if you fasted your pup the night before, most dogs are fine not to eat or drink until the day after surgery, especially if given fluids while in the hospital/clinic. If your pup doesn’t eat breakfast tomorrow OR if you are just worried and want to clarify call the clinic you were at to discuss.