Can't believe i didn't see this thread sooner either-also my favourite subject. I am a lurcher fanatic and masquerade as the local vet when not fell running. I own the best dog for training with ever- no argument, and that is the mighty Brown Dog. She is the ultimate canine athlete, i will not have a word said against her.
I am not in favour of feeding them much if anything during long runs. They are built to go long distances and have infrequent large meals. With lurchers and other deep-chested breeds gastric torsion is a risk. Brown Dog has run for over 10 hours with plenty of energy eating nothing but a stolen cake from a passing BGR participant..
Speaking of stolen cake, the dog on my avatar, who is frankly useless at running, ate the end off someone's wedding cake at the weekend!