I have three dogs, two are very good watch dogs the other one, not so much!
This is Ralphie, hes a chihuahua ****z zu mix
This is Bobby, hes a wheaten, he is an amazing dog, very smart and protetive!
This is shaina, shes a pitbull, she doesnt listen at all, shes wild and sometimes out of control but shes a good girl and very protective.
I dont think they would seriously attack aneyone but they will hear you coming and warn me.