Having owned 3 GSD’s, I agree w/all of the posts saying that you have a very smart reactive dog. In the immortal words of Hilda Gurney (to me, unfortunately:o), “she’s a Ferrari and you’re riding (training) her like a dump truck”. (THAT was a fun clinic:D)
You MUST find a trainer who knows shepherds, and I agree w/ the idea of contacting schutzhund trainers and clubs for their reccommendations. Get this help ASAP–this dog can only get worse (WAY worse). GSDs absolutely MUST have a job, be it obed., search and rescue, etc. Always remember what these dogs excell at–schutzhund, police work, tracking, S and R…HARD high-pressure jobs. GSDs are masters of the “what’s wrong with this picture?” game, and notice very small behavioral changes or non-reactions from handlers or other dogs, and they may react to them, just cuz its something to do, and woe betide the trainer who doesn’t respond!
I agree w/everyone above that exercise alone, esp. free-for-all fetching, isn’t the answer for her problems, since there is no discipline or problem solving in it.
If she is a good retriever, another thing you could do is contact a retriever field trial or hunting test trainer-lots of those in the UK, I believe-dogs must wait for an object (real birds, fake birds, bumpers-you can use bumpers exclusively)to drop and then are sent on command, and graduate to double and triple retrieves (3 “birds” thrown in succession- dog watches or “marks” each fall, then is sent for each in succession), and blind retrieves, where dog doesn’t see “bird” fall and is guided by whistle commands and hand signals to “dead bird”–up to 300 yds. away. Retrievers must learn to “honor” another dog at the line-meaning they must sit quietly at handler’s side while another dog works. Its great dog work, and she must learn patience and focus, plus its fuuuun!
DONT let her go before you through any door or gate.
DONT let her pass you on the way up or down stairs–you go up/down FIRST. Squish her against the wall if she tries to ignore this.
DONT let her walk ahead of you on walks. I am adamant about this with every young dog I train-dog in front=the boss, and dont let anyone tell you differently…its not easy w/any GSD to have them TRULY in correct position (tip of nose at the outside seam of your jeans)–they like to be just A LITTLE (to a lot) ahead of you-this is a big deal to them, and if you win this battle, you are on your way to winning the war of “I mean what I say”.
As to collars, I know exactly what I’d do w/her right off the bat-high-collar w/a well-fitted small link choke collar and a soft thin 4-6 ft. lead, shortened so that when she’s at your side in CORRECT position (above) and your arm is down and relaxed (NOT at your waist-this isn’t competitive obed. but control, and YES it is just like Cesar M, but I’ve been at it lots longer than him;), and IT WORKS), the lead is loose-no pressure at all, but its very short-probably only 4-6 in. of lead under the snap. If you’re unfamiliar w/high-collaring, its when you move the choke collar up right behind her head, right behind the jaw and behind the skull-you can also use a thin slip lead for this. When you control the head you control the dog, and this is now how we walk on lead, forever until she EARNS some freedom–My dogs w/o issues are often allowed out in front–they must prove to me they listen, and then I leave them alone.
I know people in the UK are very vocal about collars some believe to be cruel, but they are like bits-it all depends on the hands connected to them. I dont think a prong is your best option, though, in this situation, at least not without very experienced supervision. I use them when needed, usually to “retrain” a dog’s neck or when I have “little/BIG” or “BIG/old”, (little person/BIG DOG or BIG DOG/old person) but if you deliver pain when she’s at mid-launch, you may end up with a worse problem-a now fearful reactive dog who, being a GSD, may equate that correction w/other dogs-not what you want. That said, if you work with a trainer who wants to use the prong, I say do it-it has changed many bad dogs into good dogs–but it should be used as a step to getting her to a plain buckle collar–that is your goal.
I do believe you can learn from Cesar Milan about gaining and keeping attention. I do not view what he does as punishment. That said, I agree with some here that some people try to copy what he does can get themselves in trouble-its not easy teaching people!