Laura, I am sorry to hear that Princess is not doing well. I would wonder about cancer too with her history - except, maybe her appetite would not be that great? When did you have her T4 last checked? And was it Free T4 by ED? I can't think of anything else that would cause weight loss and a ravenous appetite - well, tape worm. You have to check a fresh stool (unburied) to see the segments. One of mine had that last year seemingly out of the blue. But my crew had fleas about 6 months before that.
I hope Bagheera feels better. Has he had ptitis before? Mine are all shedding like crazy, with this early warm weather, and tossing up furballs, which can make them not want to eat right beforehand. His numbers look good.