In theory, an adult dog can stay in a crate for approximately six to eight hours in a stretch, whereas a puppy can spend two to four hours in a crate in one go. This is because they have smaller bladders and need to relieve themselves more often.That said, it's not appropriate to crate your dog for eight hours per day, every day, and then again every night, as he’ll lack mental and physical stimulation. Many dogs are shut in their crates just until they're toilet trained and have passed the puppy phase, when they want to chew everything. After this the door is always left open, so the dog can choose to lie in his crate when he wants to.