dont have to with 1 of them, not (natural) guards , like Mals,GSD,Rotties. But if they do guard they would do more damage, they dont switch off once they wound up been round bull breeds since i was a kid, wouldnt be my choise of a guard dog, rather have a well bred GSD.
i admit i never got her for that purpose bird but ino my kennels are secure whilst shes out side..
if i was looking for a gaurd dog it would have to be gsp