Goes back to that old saying Its the size the fight in the dog not the size of the dog in the fight,
But pure whippets anit going to be your first choich if your after a foxing dog, There size alone holds them back i think (i prefere types that can pick up off the floor and give a good shake), And then you got there skin that tears like tissuse paper and do take abit of stick,
But then again iv seen little 18 '' whippety dog smash foxed to bits pre-ban,
So yes whippets can kill fox (pre ban)