I can't say because I really don't know. I know they never forget, though. It's been about 11 years and Duke hasn't forgotten his bad treatment. Now I have a good excuse to tell you how much I LOVE your new sig! Very, very cute. We need some more Nicki pics, also. I'm a member of the Nicki fan club.
Edited: Forgot to add that a black person here at work had an idea about this. They mentioned a dog barking at white people. Maybe it's just because they're not what the dog is used to being with, you know? I think it makes sense.