Dogs ears are indeed sensitive to altitude. Traveling 8,000 feet above sea level, such as during a flight or while climbing a mountain, can be problematic for some dogs.
Ears and Balance
Dogs' ears help them with balance and are responsible for helping them sense things in their environment. Their equilibrium may be affected at a high altitude, so in this way, their ears are effected. Veterinarians recommend ascending to higher altitudes with a dog at a gradual pace. A gradual change in altitude will help your dog to naturally adjust. It's important to be in tune with your dog while traveling in high frequencies. If you notice rapid breathing, dizziness, panting, dry cough, excessive drooling, pale gums, or if your dog refuses to move, your dog may be suffering from altitude sickness. An oxygen mask may help to reduce symptoms. Preferably, the dog should also be taken to a lower altitude. Seek veterinary care as soon as possible.