Guide dog

A guide dog does not read traffic lights. Its handler listens to the traffic and decides when to cross; the dog holds a straight line, stops at kerbs and steps, steers round obstacles including ones at head height, and refuses a command that would walk its handler into danger, a skill trainers call intelligent disobedience. In New Zealand, puppies spend about a year with volunteer raisers before around six months of formal training, and Labradors, Golden Retrievers and crosses of the two fill most harnesses.