on our property. any person or bicycle that passes by our home is fair game (in her eyes) to chase and try and herd (nipping at their heels). since we can't call her back when she starts to run at someone, we need to keep her tied when she's outside. it's safer for everyone involved. she a very smart dog, however, and very loyal to our family. our home is "her" home and she lets anyone who comes on our property know that she's on guard. 