I must be missing something, a 20 month old collie lurcher dog pulls up and comes back whilst chasing a rabbit,various health/lack of running quarry reasons.......its ok ,its fine,dont give in with it keep trying......A saluki lurcher pulls up running an hare,at any age,no matter if its its sixth hard run.......its a jacker and has to go...?? whats the difference........daylight
when a collie x jacks its because it means they must be clever
not clever enough to predict the prey might make a mistake though