Out of the loop

That's not the way RFID works, it's an old tech only capable of sending it's code which remains static. The chip gets read and the # is cross referenced with one of 4 or so databases the vet has access to, who then calls you and says "hey we found your cat."

So basically if I did that and got lost, my vet could call me and tell me they found my cat (which is me), but to know anything about anyone's kidneys they need a urinalysis.