I have a female american bull dog who is just over 2 years old and is very calm and trained. However she has the tendency when off the leash to want to walk on the road. How can I successfully train her to know the difference?
One way is to train her to stay with you without a leash. When she stays by your side, you can teach her to walk away from you. When she knows both, you can let her walk on her own. If you see her walking on the road, call her immediatly and let her stay a little while with you (e.g. 1 minute).Then give her the command to go away and let her walk on her own. If you see her walking on the road, again, call her...
Staying by your side is less fun than walking on her own and if you are consequent and have a good timing, she will understand.
Don't punish her if she is walking on the road. If you want her always staying away from the road, even on 'new' ways, always be consistent and don't have any exceptions.
Keep her on leash and walk the perimeter so she knows her area. Consider a retractable leash and use it to train her on "stay" such that the leash is slack and she can walk to the perimeter and be governed if she attempts to go over. Consider a harness rather than a neck collar leash if she is a strong bolter. Take it slow. Be consistent with your training. Start out very restrictive. Until she is responsive to your voice command, don't let he off leash outdoors. Reward her with affectionate petting and rubbing and treats (in moderation) when she follows commands.
It takes a lot of slow, careful, consistent, patient work to teach a dog where NOT to go so that they will do this without needing to be constantly monitored. You'll need to take a few steps back and keep her on leash.
The first thing you should do is practice recall until it is very very solid meaning that no matter what she is doing or what she is interested in, you can call her to come back and she will immediately stop what she's doing and come back. Good recall can take years of consistent and patient work.
This is very important, because if her recall is not quick and consistent, then you may not be able to keep her out of the road when traffic is coming.
While you work on this, also make the dog walk around the perimeter of the road to give her a sense of the boundaries of her play areas.