The event requires a handler and man's best friend, a working sheep dog, to herd a group of sheep into a pen. The handler can only give communication to the dog to accomplish this task in the fastest amount of time.
Many of the dogs seen on the trials field will have been at work on the farm, probably that very morning before setting off for the trial. It is true to say that the skills they acquire in their everyday work are key to them gaining maximum points. The system of scoring at trials is that a maximum number of points are allocated for each element, and dog and handler actually 'lose' points for any faults as they progress around the course.
