Which episode was this....

Which episode had a family traveling on an intersection and they spot a dog and a child in the car asks the driver to stop and pick the dog up because they are afriad the dog will get hit by a car. The child keeps begging so the driver agrees. They get back on the road and they come to a traffic jam. They soon find out their was a pile up and several people died and if they didn't stop they would of been in the pile up and the dog may have saved their life.

Seemed fake as most parents wouldn't pull over to pick up a stray dog with their children in the car as it could have rabies but it was fact.