whether you have a dog or not most burglars will make entry thru the rear. you should always have a beware of dog sign posted and a very LARGE dog bowl filled half way with dog food with a chain leash with a very LARGE dog collar attached to it.
a would-be burglar will simply go on to the next house when he sees that. he will just assume their is a big dog in the house and burglars dont want to screw with big dogs and arent taking a chance on it being a small one with such a large dog bowl and collar located outside which obviously means the dog is inside the residence.
trust me that is far better then any alarm system or gun will ever be. an ounce of prevention is worth a pound of cure....