Sea,
What everyone else has said, except here is an excellent twist:
"Oh, the cat has [diabetes, thyroid problems, kidney trouble] and he needs his medication every day. I've just had him in the hospital again but it ONLY cost $2000 this time, thank goodness the vet lets me run a tab, you'll take responsibility for the back bills, of course, when you take him, I'll call the vet right now and give him all your contact information. He'll be going back in for some tests in a couple of weeks. He's getting used to the subcutaneous fluids now, that only has to be done twice a day and it only takes ten minutes each time and he hardly ever scratches me now..."
If they have to do anything, and I mean anything, to care for an animal, they lose interest FAST.