That's a Good Question,,I would Say at Least 3-6 months Old ;) Depends Really on what kind of Dog ;)

Please don't get me wrong, I am a dog lover but the fact is you really shouldn't take it on a plane. I travel all the time and have seen people with pet dander allergies sit there and sneeze for 5 hours straight.

I would say that for an optimum adventure in general comfort...you would want your puppy to be old enough to HOLD IT (urine and feces) for as long as your flight will be! Otherwise, there is likely to be an accident! I would also suggest that you be sure to feed and water the pup WELL in advance of the flight...and withhold food and water for at least 8 hours before...just as you would if the puppy was going to have a surgical procedure...you would be sure to provide water ASAP after getting off of the plane and then food within a short time after that! While not "written in stone" the general rule of thumb is that a puppy can "hold it" for one HOUR past the number of months old the puppy is....so, for example, if your puppy is three MONTHS old...he/she should be able to "hold it" for about four hours.... So if you feed and water about 8 hours before the flight (you might get by with a last small drink 6 hours before take off) your puppy should be able to cope without an accident, assuming you give the pup LOTS of potty opportunities before boarding. http://hubpages.com/hub/Natural-Remedy-to-Calm-Dogs-Bachs-Flowers http://www.rescueremedy.com/ http://feelbach.com/quick38.asp?refID=gl2b1 http://www.vitaminwarehouse.com/Shop/Brands/index.cfm?b=11578&rfr=ggl&kid=9387 Assortment of prices...hopefully one will work for your needs.