Johanna Waterville, ME 4/30/2012 1:02:07 PM Great info! I would also add: DO NOT use a head collar in combination with a long line or retractable leash, as the dog could get whip lash if he decides to run. Only use head collars with a standard 4' or 6' leash. Also never give a corrective jerk or leash pop with a head collar. DO NOT use choke or prong collars unless you are a trained professional or are working with one. Spinal, nerve, or tracheal injury can occur if the dog is allowed to continually pull against this type of collar, or if the walker incorrectly "yanks" on the dogs neck. DO make sure your dog's collar fits correctly. Collars that are too loose can come off, while ones that are uncomfortably tight can irritate the dog and cause him to be reactive.