BHWW I owned a cat who went through a similar situation, except it wasn't a huge abscess. There was like a little bump on top of his head that started slowly leaking a pale green pus. While I was trying to get the local vet on the phone the pus started to run down the bridge of his nose and the poor dumb cat tried to lick it.
mouser The preload image alone is worth the rating.
Strange the vet didn't have a wet sponge or something nearby for the cat. It's the anesthesia that makes them thirsty.
FABIO Food and liquids are a bad idea under anesthesia.