Ruh roh. (Shutterstock/ WilleeCole)

Frequent flyers with four-legged friends probably already know this, but short-nosed dogs like bulldogs, pugs and Boston terriers are being banned from many airlines. The reason? They keep dying in transit.

Brachycephalic (short-nosed) dogs often have breathing issues because of their stunted snouts, which means they can easily overheat—a dangerous situation when they're flying in the hot cargo hold area of a plane. Delta banned brachycephalic pets this year after several bulldogs died on their flights. So did American Airlines, and United and Continental, at least over the summer when temperatures rose.

Naturally, a niche market for pricey pet-only air travel has sprung up to accommodate dogs that must be flown: Pet Jets encourages animals to "joint the pet jet set!" by boarding a chartered plane, and Pet Airways will get Fido from point A to B if you have the cash to burn (a one-way cross-country flight clocks in at close to $900). “If he throws up or gets sick or goes bonkers, there’s going to be a human being there,” one French bulldog owner who used Pet Airways told the Times. “That makes it worth it for us; we’re paying for peace of mind.”

If you need to travel with a pet and can't do it on four wheels, here's a list of airline pet regulations to review. Or, get someone to drive Sparky for you!