i would like to acquire a dog for general protection, but am very picky. i need the dog to be medium size, under 50lbs, and not a pit bull. i also do not like aggresive dogs like rottweilers or dobermans. i think 75% of the people who own them should take a mandatory obedience class, because their animals aren't trustworthy. i have had boxers and found them agreeable with kids and "protective" enough, but health problems ruined all of our boxers. is a australian cattle dog a good protector? i would like to be able to have the dog around my 2 year old nephew and other dogs in our family circle. i really just need something that will wake me up and would make someone hesitate. a bite is not imperative.