Dog doors can be safe, but it depends on where you live and what’s outside the door. That’s why it’s important that you only install them on your door if you have a safe, fenced-in yard and take certain precautions as a pet owner. Otherwise, your dog could wander off and get lost, or risk getting hit by a car. You’ll also want to consider what critters might visit your backyard. “While your neighborhood may seem safe when you’re walking with your dog, things can change when your pup is out on their own,” Philips said. “Depending on where you live and the size of your dog, you’ll need to consider predators like coyotes and even birds of prey like hawks when it comes to smaller dogs and toy breeds [because] these animals will generally avoid humans but may be bold enough to go for your dog.” Remember too that you need to make your yard safe for dogs, which means routinely checking for toxic plants and weeds, as well as holes in the fencing. In really hot climates, you’ll also want to keep your pet inside to make sure they don’t stay outside too long, which puts them at risk for heatstroke. That’s why several of the vets we spoke with recommended keeping an eye on your pet through the window, even if you do allow them free access outside through a dog door. Remember too that any critters in your backyard can also come inside your home too—which is why you’ll want a locking one or an electronic one. This can also protect against burglars if you have a larger dog.