A carry-on bag is included in Lana Joseph's ticket price whenever she flies from Cleveland to Fort Lauderdale, Fla., on United Airlines. But if that carry-on includes Molly, her six-pound Yorkshire terrier, Joseph has to cough up an additional $250 round-trip. "That's way too much for a bag that goes under the seat," says Joseph, a retired hairstylist from Akron, Ohio, who spends her winters in South Florida. "I can see a small charge, but not an exorbitant fee." Welcome to the topsy-turvy world of pet travel - a world that some say shouldn't even exist. Americans spent an estimated $55.7 billion on pets last year, according to the American Pet Products Association, most of it on food and veterinary care. But an unknown portion of that amount also paid for plane tickets and accommodations for man's best friends. It's one thing to travel with a service animal, which performs an essential function for a disabled passenger. But it's quite another to bring your dog, cat, rabbit or bird on a leisure trip because you want to. APPA President Bob Vetere has called this the "humanization" of pets - or, in travel terms, the belief that Fluffy would be sad if you went on vacation without her. Depending on your perspective, the travel industry has either accommodated those feelings by offering pet-friendly rooms, restaurants and flights, or it has preyed on them by adding fees and surcharges that do little more than line its pockets. Certainly, accommodating a live animal can be an extra burden on any company. Airlines are required to file monthly reports with the Transportation Department on pets that were lost, injured or died during transport. United has reported a total of 89 pet deaths since 2005, according to the Web site ThirdAmendment.com . Still, United's travel program for animals, called PetSafe, is said to be one of the most pet-friendly in the airline industry. United inherited PetSafe from Continental Airlines when the two merged in