Congratulations! I went looking for a pic of the young thing, but found one when I googled - definitely a dog with a personality.
There are two things to consider here - is there a medical reason, or is this an emotional/training reason?
Medical.... BMD's are particularly susceptible to lyme, so you have to wonder if the parent ever had lyme and might have passed it on when your pup was born. Being a farm dog, was there exposure to anything else that might be causing an issue? Joint issues can cause reluctance to walk. Digestive issues can too. There may be other reasons, but those are the ones that popped into my head.
The training aspect. I know you don't want to hear this, but I have to say it. There is no way that a 9 week old pup should be showing aggression, or should be on a choke collar. If there is something that looks like real aggression, I would be looking for a medical reason (like thyroid). Most of the time, this behaviour is mistaken and is really something else. We see this all the time on the GSD forum, where dogs are labeled aggressive, when they are not (they are land sharks when young, often misunderstood).
It was said earlier, but walking, and enjoying being near you, and coming to you, and following at your side, starts inside the home, and can be taught through play or lots of positive encouragement. That can be transferred to a confined outdoor space (still without a leash), and then transitioned to a leash. It sounds like maybe the relationship isn't there yet, and she's shut down.
Last year I got my first pup in over 13 years. Boy, all the things I forgot.....
My goal when I got my pup was to teach as much as I could through play and prey drive, which has been a lot fun for both of us.
So, I guess my questions are, how does she behave inside? How does she play? What does she play with? Who does she interact with and how? The answers to these questions I think also help determine if she is reacting normal, or if there might be something wrong.
Another thought....also talked about earlier. This can be quite a shock for a young dog, moving to a new home. When a dog is rescued, many rescues encourage a period of two weeks for "shut down", where the dog gets two weeks to just sit back and figured out what just happened to it. I did a modified version of this when I adopted jazz, and I think it helps a lot.
This is for rescue dogs, but I think it applies to new pups also, to a large degree:
Rescue handout sheet:
more from Jean: http://germanshepherdhome.net/forum/...day#Post283942
Ahhh, another thought - puppy stages. Looks like she may be in a fear period:
She needs lots of encouragement and positive reinforcement.