I use a collar on morgan for training purposes sometimes and a little 'pop' isn't going to hurt your girls. Unless they are constantly pulling against it or your dragging them all over the room by it then you shouldn't have a problem. You do have more control over them with a collar because when you give them a little pull they have to turn around towards you. With a harness you can pull them all you like and they don't necessarily turn towards you. It doesn't get their attention like a collar because they don't direct them where you want them to go.
__________________ Kellie  and  Morgan |