Thousands of pets and exotic animals are shipped successfully each year, though their travel options are somewhat limited to air and auto transport. Buses, trains and boats are usually out of the question for anything but service animals, though certain carriers may have their own rules. The Humane Society of the United States recommends that pets go by air only when "absolutely necessary" and question­s the safety of putting a pet in an air cargo hold [source: Humane Society]. While you could certainly drive a pet cross-country or fly an airline that will let you to take your pet as carry-on luggage, sometimes that air cargo hold is your only option. But there are many rules in place to make sure it's as safe as it can be. If you're the kind of person with a disregard for authority and a penchant for rule-breaking, then shipping a pet via air cargo is not for you. The process of pet shipping involves a whole host of regulations that pet owners must decipher -- pretty much every airline that will carry a pet as cargo and every country that will receive a pet has their own rules and regulations for pet shipping. This is one of the reasons why many people pass the responsibility off to a pet shipping service, which will figure out all the rules, fill out the paperwork and ensure your pet meets you at your destination.