I do know a very frequent flyer who flies with his certified companion Golden Lab (and a big one at that). She is in a special program to be a "helper dog" at hospitals, nursing homes, hospices and the like in certain parts of the country (but not for her traveling companions.) The only thing I have known that the owner was told is that the dog cannot be in the emergency exit row or the bulkhhead, and must sit in a row with one of her certified handlers. (She usually travels with 2 to 4 certified handlers.) She wears her "official" vest and is sweet to the nth degree, doesn't let anything bother her (and usually sleeps 90 per cent of the flight) and doesn't even think about being in a box. The owner has also done the same thing with the dog and the dog's sister, on fewer occasions, to about the same reaction: none. Perhaps it is a little different because these are "professional dogs" but I would be happy to sit next to one or both anytime. ...