Why is it that we always say: "He's like a pit bull that won't let go when he gets a grip" ?
And think of when we say that and in regards to what kind of behavior.
I don't think I have ever heard: "He's like a poodle that won't let go when he gets a grip."
Whenever one wants to make a point about something that just won't let go, they use the pit as an example. And in the next breath, tell us that they are nanny dogs.
Old wives tale?