I've driven animals to and from CA with carriers in plain site - they never ask what's inside. They just want to know if you have bananas or something.
I think that there is a law that you have to have a health certificate on animals, but I think that they pertain to livestock and cattle. I suppose that the chins could fall under that category. It's just that chins aren't really the type of animal that are going to be dangerous to agriculture or make anyone sick. They're probably less of a danger than a family dog or cat. I wouldn't worry too much about it. It's not like you're going to be taking cattle across state lines...like Peggy said.