You've lived together for years now, and although you don't always get along, I like to think that we've reached a certain state of equilibrium in our house. There's the occasional wrestling, and sometimes clumps of someone's fur hang from someone's mouth, but it's generally peaceful. I catch you snuggling from time to time, and there are forays in to feline lesbianism, so don't try to pretend that you don't like each other.
So why is it that you forget all that whenever we move or take you to the vet? Are your brains really that tiny? At some point during a ten-minute car ride, you cease to recognize each other. You approach your new home as a blank slate, no matter how familiar the furniture is, or how much of your hair covers the bedspread. You hiss and growl at each other like strangers. Then, after a few hours it finally dawns on you: "Oh yeah, she's that cat I've been living with for eight years. Maybe she can be trusted."