Dogs often fly as cargo on airliners. I'm not positive, but I thought the cargo area wasn't pressurized or not pressurized the same as the cabin.
Of course chilling in a crate at 20,000 is probably easier than hiking at 14,000 feet.
A few years ago there was a dog who hung out on the trail between trail crest and the summit. Must have lived off of hand outs until someone got him down.........................DUG
