A large dog is one of the few things that can actually prevent most break-ins.

Story time: There was a serial killer in CA a few decades ago. The police mentioned he doesn't attack homes with dogs, next victim had a small dog. Next the police mentioned he doesn't attack homes with medium or large dogs, next victim had a 30lb dog. Next the police mentioned he doesn't attack homes with large dogs. His next victim didn't have a dog. If its 80+lbs, very few people will mess with them and they will love you forever.