The most you can usually leave your dog home alone is around eight hours, or a normal workday. Any longer than that, and you'll need to figure out something to do so your dog can go outside and have some puppy play time. Dogs are social animals, after all, and leaving them alone for long periods of time can have devastating effects. Even though they sleep most of the day, they need some interaction with other living things, as well as potty breaks, throughout the day to keep them happy.