I have read on this forum that onions are toxic to cats. I just caught my 20 week old kitten licking a bowl of some stew with onions in it. I don't think he ate actual pieces of onion but I'm really worried. Since it is a holiday, I can't call the vet and I would like to know if this is really serious. Are onions like a poison or is it just toxic in large amounts? What should I do?