I know that specially designated service dogs can go in the cabin and don't have to be caged. A woman at my local dog park said I should go to an office nearby who does such things and have my dog certified as a service dog. But my German Shepherd is just too friendly and frisky to be in the cabin...she's sweet but would be a nuisance. I assume even service dogs don't fly for free, so perhaps they have to have a purchased seat.