Thanks for your response. This is new behaviour that has started recently. I have had her for 1 year and no previous issues. It is quite random and doesn't happen every time we walk. She has always been ok walking on a leash - although she does walk slow and usually behind me. Off leash in a bush setting she flys around and loves it. She is used to a leash and harness and not scared of anything, although is startled sometimes by loud/close noises. She was a show dog and is very calm. I was using some kibble to get her to keep up/heel. If we turn around to go home after she puts the brakes on she starts trotting happily and runs around excited for a minute when we get home. Tried to continue in the other direction from home but she stopped again. She is black and gets hot easily but I usually walk early in the day when it's not so hot. Not sure how to get her some excercise if it's too hot for her outside. Any suggestions? I will try some different treats when walking rather than kibble.