As a vet, I also see lots of application of Alexander Technique to our communication with animals. A greater awareness of our posture and stress responses can influence how animals react to us.
Having a good relationship with your dog and enjoying relaxing walks is a great way of helping yourself with your any chronic pain, including back pain.
You can help your dog relax by having a calm, confident posture with minimal muscular tension. This signals to your dog that there is nothing to worry about. He will then be in a much better state to learn if you are training, or just to enjoy a stress- free walk together.