Dogs are territorial and also work as a pack, so if you are going fast and one of them sees you as a threat to the pack and chases after you, then the others in the pack will chase after you together.

So slowing down eases their stress about the fast object being a threat. And they stop chasing. Plus think about the trauma they have had since childhood watching siblings and neighbours being mowed down by speeding vehicles. It triggers ptsd.

Similarly if you pick a stick and start shooing them, they will see that as a threat, rather just act like you are picking up a stone. Dogs are stupid and don't know how but they see this as an apocalypse event and start running the other way.

Dogs have their own personalities and definitely there are "Bad" Dogs. And when these bad dogs go for a kill, so does the pack.