The only way they will allow him to travel this time of the year (winter!!) is with you in the cabin. So there should be no problem if you go to Idaho to pick him up. I would think you would want to anyway. (Mind you, I almost adopted a cat without meeting her in person but she came highly recommeded by someone I trusted
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I recently flew with my kitten to Florida on AC and experienced no problems at all. I would never ship a cat or dog this time of the year though. It is too cold and even in cargo at the best of times, there are oxygen problems airlines will not inform you about.
So, if you really want the dog, I would travel to Idaho and bring him back with you. You also have to check with the airline. Ever since a nervous cat got loose and attacked the pilot - making the plane make an unscheduled stop in Nfld - planes now require only one pet per cabin. (I really am not certain if that incident alone led to this but it probably did not help).
Good luck!