Expert: Jill Connor, Ph.D. - 2/3/2012

Question
We have a 5 year old female german shepherd (not spayed yet) who is a wonderful, smart, amazing dog: however, she is extremely protective of our 1 acre lot when it comes to strange dogs.  We live out in the country, so the only dogs that she has ever encountered have been wanderers - all of whom she will charge, attack, and then let go when we yell at her.  The problem that I am now encountering is we just got new neighbors - they live right next door to us.  The only thing seperating our lot from theirs is pine trees.  And you guessed it, they have 2 small dogs - a mix breed and a chihuahua.  You can only imagine how horrified we would all be if she attacked and killed our neighbors dog.  So, I'm wondering if it's possible to help her NOT BE SOOOO TERRITORIAL???  My fear is that their children, or ours, will accidently allow their dog to wonder into our yard.  She is sooooo fast.  She is not usually out in the front yard, but it could happen.  If she hit a tiny dog the way I've seen her hit a large dog - she basically plows into them to knock them over, she may just kill it from mere impact.  Any advice would be helpful. Should I get her a muzzle?  I know she can respect other animals because we have many animals - 10 ducks in our back yard, a miniature horse, and another large dog that we brought home as a puppy.  I was determined to teach her how NOT to kill small animals when we got our ducks - and now she helps me to herd them into the barn at night.  She also will sit out in the yard and watch over them - but never hurts them.  I know it's possible, I just don't know HOW to teach her.  She's very willing to learn.  Oh, and she's never been aggressive towards people.

Answer
This is one of my favorite breeds for many reasons and their strong predilection for protection (best left to nature, no "training" required) is one of them.  This is HER territory, SHE feels responsible for what happens on HER territory (I'm assuming the second dog you own defers to her in most things).

You must make the FRONT YARD a no-dog zone in her mind.  You do this by creating a psychological barrier (barrier training) as you see demonstrated here:
http://www.youtube.com/watch?v=NCuY9uX7ods&feature=related

The dog MUST understand that crossing THAT threshold is NOT AN OPTION WITHOUT BEING ON LEASH WITH YOU (so obviously you cannot use that door to let her out).

You also want to be sure that what you're seeing is as serious as you think it is.  You say she "lets go when we yell at her" -- is there physical damage to the other dog?  Does the other dog require veterinary care?  It's important to make this distinction.  Your dog may not be as aggressive as you think; it might be your perception:
http://www.youtube.com/watch?v=FD36oXBxAuQ&feature=related

If it IS benign, she'll STILL demonstrate this bullying behavior toward the neighbor's dogs unless she's been properly "introduced" to them and they are not strangers to her.  The presence of the other dogs will be WELL KNOWN to her.  She can't walk around wearing a basket muzzle all day long (and a dog knows it's restrained when wearing a muzzle which can make aggression worse).  She must be dissuaded from this over the top aggressive response.  One way to do this is to "teach" her to "get it" and "drop it".  Children should NOT participate in this "game".  It begins with teaching the dog "off" or "leave it" over a tidbit of treat and then progresses to a toy (stuffed or pull toy) where you can elicit a real rough and tumble play response (with growling and tugging) that will IMMEDIATELY stop at your cue : "Drop it".  This will then begin to transfer to other objects.  She should ALWAYS be rewarded for compliance.  Using food to begin this training is demonstrated here:
http://www.youtube.com/watch?v=QEyMoQmdLO8&feature=related

The best approach to a situation which might, if your dog is serious in her aggression, end up in tragedy is to bring in a certified applied animal behaviorist (NOT a dog trainer) who can arrange for all dogs to meet off the property, on leash, where body language can be observed and a determination made on the spot regarding the motivation behind your GSD's behavior and just how serious a threat she is.  I would rather err on the side of caution and absorb the expense of a session with a CAAB than face a lawsuit, an injured child who attempted to intervene, animal control seizing your dog, etc.  To find such a professional see the following sites:
http://certifiedanimalbehaviorist.com/page6.html
http://www.animalbehavior.org/ABSAppliedBehavior/caab-directory