The skies aren’t friendly for everyone. For many dogs, cats and other animals, flying isn’t fun—it’s frightening. And in some cases, it can even be fatal. That’s why, if your summer plans include air travel with your animal companions, it’s vital to take every precaution to ensure that you can do so as safely as possible.

The most important thing to do is to promise your animal family members that you’ll never treat them like luggage. That means never forcing them to fly in a plane’s cargo hold.

Why? Every year, cats, dogs, rabbits and other animals die in cargo holds because these areas are designed for luggage—not living beings. They typically aren’t ventilated or climate-controlled, which puts animals at risk of exposure to deadly temperature extremes.

In 2020, a 12-week-old puppy named Sebastian was found dead after being flown from a breeder in Ohio to Los Angeles, and a leukemia patient’s two dogs both died after being flown in a cargo hold from Dubai to Washington, D.C. In Canada, 38 French bulldog puppies were dead on arrival—and dozens more were dehydrated and seriously ill—following a flight from Ukraine. Those are just a few of the incidents that made headlines. Many others go unreported.

And if you’ve ever opened your suitcase after a flight and found your carefully packed clothes in disarray, you know that items sent down an airport conveyor belt aren’t exactly “handled with care.” That goes for animals, too.

Dogs and cats have been sent on the wrong flight, ending up in an airport on the other side of the country from their frantic guardians. Others have gotten out of their carrier during handling and bolted across the runway or gone missing. Some are never seen again.

Even if all goes according to plan, the experience of being separated from their guardians and stowed amid the baggage in a noisy, dark, strange place with fluctuating air pressure is downright terrifying for most animals. They have no idea what’s happening, how long it will last or even if they will ever see you again.

A study published by the University of Illinois found that for dogs used in search-and-rescue missions, air travel is so unsettling that “[t]hey showed behavioral stress, their gut was completely turned upside down, [and] their bloodwork showed significant effects.” If flying is this upsetting to dogs who presumably fly regularly, imagine how terrifying it must be for dogs and cats who are used to spending their days quietly napping on the couch.

So, while you’re dreaming of seeing the world, consider whether taking your animal companion along at all is a good idea. Will they enjoy the trip, or will they be stressed by flying and have to spend most of their time alone in an unfamiliar hotel room, while you’re out sightseeing? For many animals, staying in their own homes with a trusted caretaker is the safest and least stressful option.

If you must fly your animals, check the airline’s policies well in advance of your trip to ensure that they can ride in the cabin with you. Usually, this is only an option for animals who are small enough to stand up and turn around inside a carrier that will fit under an airline seat. Make sure the carrier is sturdy and well ventilated, and leave the door open, with treats, toys and a soft blanket inside, during the weeks leading up to the trip, so your animal can become acclimated to it.

For animals who are too large to fly in the cabin or who would be a nervous wreck, driving them to your destination or even going by boat are better options.

It is not worth risking our animal companions’ lives, even for long-awaited trips.