Originally Posted by baddog

According to the American Veterinary Medical Association, in most cases cats and dogs should not be given sedatives or tranquilizers prior to flying. An animal's natural ability to balance and maintain equilibrium is altered under sedation, which can be dangerous when the kennel is moved.

Whether flying as a cabin or checked pet, animals are exposed to increased altitude pressures, which can create respiratory and cardiovascular problems for dogs and cats which are sedated or tranquilized. Brachycephalic or snub-nosed dogs and snub-nosed cats are especially affected.