Because of their shortened muzzles and noses, brachycephalic dog breeds are prone to severe respiratory issues. As the American Veterinary Medical Association (AVMA) states, short-nosed dogs “don’t breathe as efficiently as dogs with normal-length snouts and can have difficulty cooling off when they’re playing or exercising, or if they’re stressed or overheated.”
In most airlines, if your dog cannot be taken into the cabin as a carry-on (because they’re too large or are on that airline’s list of restricted dog breeds), they are put into the airplane’s cargo hold. The problem with this is that temperatures and air quality in a cargo hold—even one that is pressurized and kept similar to the passenger cabin—can shift severely during the flight.
As the AVMA article notes, “Because of their anatomical abnormalities, short-nosed breeds seem to be more vulnerable to changes in air quality and temperature in the cargo hold of a plane.” Additionally, because there’s no one in the cargo hold to watch your pet at all times, if your short-nosed dog has a problem midflight, they won’t get critical care right away.
This has led to numerous deaths of short-nosed dogs during airline flights—forcing a change in airline pet policy.