According to American Veterinary Medical Association (AVMA), air transport of sedated pets may be fatal. Over sedation is the most frequent cause of animal deaths during airline transport and accounts for more than half of all deaths when flying. Except in unusual circumstances, veterinarians should not dispense sedatives for animals that are to be transported.
Little is known about the effects of sedation on animals that are under the stress of transportation and enclosed in cages at 8,000 feet or higher, the altitude at which cargo holds are pressurized. Additionally, some animals react abnormally to sedatives. Although animals may be excitable while being handled during the trip to the airport and prior to loading, they probably revert to a quiescent resting state in the dark, closed cargo hold, and the sedatives may have an excessive effect. - See more at: http://www.petrelocation.com/blog/pe....3UX9Ug56.dpuf