Besides blood vampires can drink water- and alcohol based liquids.
I CAN'T STOP LOVING YOUR CATS!!!
... is their poop just watery gross like bird too?
Actually they do not poop at all. They're carnivores and adult vampires eat everything from flesh to bones. Digestible matter is separeted from indigestible in vampire's stomach, and indigestible matter will be vomited. The vampire body needs huge amount of energy so everything digestible will be consumed leaving pretty much nothing but gas to let out.
The way the cat on the table is laying made me wonder WHAT IF... they finished their dinner and the cat was like, one of those ladies that you take the food right off her and eat it ffhsghs XD