A dog and a horse

My daughter and I were walking our excitable young labrador up the narrow country path, towards a corner which led to the open fields - at which point the dog would be let off her lead. ''Why can't we take her off the lead now'' she asked. ''Better to wait until we get around the corner and into the fields, since it'll be easier to spot any chaseable objects such as cyclists and horses'' I suggested. ''But we're nearly there, nothing will come'' she told me. ''It might - a horse might come round the corner at any moment'' I said. Seconds later, with the dog still on the lead, around the corner came a horse....