"the dog trotted ahead like some mute and mindless bellwether"
Little Bo-Peep with bellwether ram
Public DomainLittle Bo-Peep with bellwether ram - Credit: Joseph Martin Kronheim

A bellwether (from the Middle English bellewether) was a castrated ram (a wether) which lead his flock of sheep with a bell tied around its neck. The sound of the bell allowed shepherds to keep track of their sheep when the flock was out of sight.