BAD IDEA
Can I microwave a cat?
No. Absolutely not. That is not a cooking question, that is animal cruelty wearing a tiny chef hat.
Do not put a cat, or any living animal, in a microwave. You would injure or kill the animal. The correct move is to step away from the appliance, give the cat a treat, and reconsider the life choices that brought us here.
If an animal is in immediate danger, move it away from the hazard and contact a vet or local animal welfare service.