Back in the good ol' days (the 70s) when I was young, we were able to put our small beagle in a crate and take her on board. She weighed about 22 lbs and the crate wouldn't fit under the seat, but the flight attendants let my folks put her crate sideways against my 4-yr.-old brother's seat and he'd rest his feet on top. (We also took my tortoise, Charlie, on many flights--he was happy in a good-sized shoebox and got LOTS of curious attention!)

Nowadays, airlines are so strict. Basically, anything bigger than a Pekingese is too big for the cabin. It's a shame, too, because flying in cargo can't be very healthy or enjoyable for pets.