I agree that dogs can do a variety of jobs, but you need the right dog for the job. If I wanted to protect my home while I'm away I'd think a couple or three big mean dogs would get the job done in most cases, but I wouldn't want such animals as family pets. But I think the subject at hand is more about protecting a home from invasion while you are present, and in that case a dog can be useful as an alarm more than anything else. The dog doesn't need to be big or mean to fulfill this function. It can't be one that barks at absolutely everything, but instead one that will bark if someone were breaking in. If someone were trying to get in a door or window while I was sleeping I'm sure the dogs would sound off and wake me. My dogs have always been very friendly. I wouldn't want to live with any other type. I don't expect them to come to my defense if someone breaks in, although they might do that. I always look at it as the dog's job is to warn me of the threat, and it's then my job to deal with that threat.