Alexandra is right, We don't go and ask to do the canni-cross or husky races without a dog, so dogs should be banned from fell/trail/road races, its an unfair advantage and they get in the way, what would happen if everyone took a dog along, it'd ba a nightmare.
I did a small race last year and two people turned up with these dogs stuck to them, claiming they needed to train for canni cross races, why they couldn't just train somewere else god only knows.....

(dog lover with two dogs, who TRAIN with me !!!)