Hi Ailsa I have not used one but one of my Borzoi friends has and she recommends it highly. She said it made such a difference to her athritic dog. She also wears a bio-flow bracelet herself and says is has helped her too.
I used one on a dog who had a back op when she was stiff later in life - it seemed to work. I also wear one on my wrist and put it this way I know when I have foregotten to wear it