Minecraft wiki entry for Furniture, associated text: A pet door is actually quite simple to create and will save you the trouble of having to keep the door open for your pets, such as wolves. To make a pet door make a 1×1 hole in the wall then put pressure plates on both sides of the hole. Inside the hole, put in a fence gate. Now your pets can come in with ease and most monsters won't be able to get in (except for cave spiders, silverfish, and the small slimes)!