I wouldn't even feed him that evening, its hunger that drives animals in the wild, wolves might not eat for 3 or 4 days and its the hunger that drives the hunt ,and after running and hunting up to 5 or 6 hours and running possibly 15 miles they might make a kill if lucky, if not they do it next day,,a hungry dog is a must if you want to get the best out of him,,if you think a dog is going to drop after a few runs because hes hungry, their is something serious wrong with his everyday feed,,best of luck,,
a wolf in the wild is completely different to a running dog specificaly bred to be