Canine Behavior/Is my dog jealous or an unwanted pack leader?
I have a wonderful black German Shepherd female, who is very affectionate and active, always listening and paying attention to me. She is the ideal dog to have off leash, does not bother other humans or dogs if any would walk by and I can easily snap her out of anything. She is a very happy-go-lucky dog, especially when outside and she would do anything for a little bit of praise. She is definitely able to play and hang out with other dogs, but when meeting a new dog she becomes very insecure (without aggression) before (after a while) wagging her tail and sometimes inviting to play. In other words, she is shy. And whenever I stay in one place (for example, on a bus), and another dog comes near me, she becomes overprotective, growls and snaps at the other dog. Is she just jealous or is she seeing me as as another follower in her pack whom she has to protect? Do I lose my position as the pack leader whenever I sit down? I have no problems at all with her except the fact that she is completely unable to "share" me with another dog and her insecurity at introductions, for which I am afraid could lead to aggression. Do you have any idea of what I can do to stop this kind of behavior, am I doing something wrong? I really want to stop this, since she has bitten an 8 month old excited lab/am staff puppy and snapped at a poor 13 year old male dog, both because they came too close to me.
You are not a "pack leader". In the dog culture, there is no such thing. Social hierarchy changes (both between dog to dog and dog to human) based upon circumstance. There are rarely "alpha" dogs and these are normally rank opportunists, almost always male, and almost always intact male.
If your dog is able to play off leash with other dogs without demonstrating hesitancy (not "shy", fearful), then the leash is the cue: you are at the other end. She is unable to do what she must: fight/flight/freeze and is "forced" by her circumstance to demonstrate warning. Since she has already (by your report) "bitten" two other dogs (while on leash?), her warnings are, to her, being "ignored". Were she free to back away, it is most likely she would do that. You are also tense at the end of your leash (now) and this goes down the leash.
She is not protecting you; she is protecting herself. She has not been properly socialized on leash to other dogs in group sessions. To answer your question about what happens when you "sit down"....to your dog, this is an alert; so whatever "fear" or anxiety she has regarding approaching dog(s) it is exacerbated by your posture. (I'm unsure where in public you would be "sitting down" with your dog on leash except, perhaps, a park setting with benches).
I know nothing about Sweden, the availability of a certified applied animal behaviorist in your country, but I can post a list of international venues to find one:
I'm certain there ARE actually credentialed behaviorists in Sweden, I just have no information other than the link I provided.
For now: do not stand still in places (with your dog on leash) for any length of time; do not "sit down" on a park bench. Begin to teach "attention" as seen here:
She should "get it" very quickly. Now: take her outdoors where you know there will be no dogs (children's playground after dark, library parking lot after closing hours, etc.) Ask for "attention", praise/reward. Walk a bit, ask again. Walk a bit, ask again, jackpot reward (handful of tiny special treats). Go on your way as normal. Do this consistently for at least 30 trials (that would be 3 trials per walk for ten days). When dog is on leash with you on the street or in places where other dogs (ON LEASH) approach, cue the dog for "attention", circle left (as if following a hoola hoop), circle right, until dog's eyes are FULLY ON YOU and all response to approaching dog is gone: stop, wait for sit, jackpot; move ahead. This is counter conditioning: teaching your dog that, when she is on leash with you, she need have no anxiety, must follow your direction and cues, for reward and praise. BE CERTAIN NEVER TO OFFER FOOD REWARD to your dog if she is even minimally still reacting to the other dog, or you will be rewarding her fear.
I would question the ability of a dog that shows on leash aggression toward other dogs to freely interact with other dogs without any aggression, off leash. Dog parks are out of the question. Totally.
What you need is a "growl class" and only a CAAB, or a highly trained and credentialed trainer (positive reinforcement ONLY and a full knowledge of how to conduct a "growl class"...observe before enrolling) can conduct one. Your dog will learn (along with other dogs in the class who have similar problems) to "work", and "work" well, on leash around other dogs; there will be some desensitization to her fear and strong counter conditioning; and the trainer/behaviorist will be able to observe your dog and determine, from her body language, exactly what is going on and the precise method to use on the street.