I had a racist dog once.
I moved the fence back so that I could park in the driveway without having to deal with the fence.
My house was across the street from a building that made blue jeans. The husbands would come to pick up their wives after work.
While they were waiting for them my driveway became the place they would pee. My dog looking out the floor to ceiling window at them grew to hate blacks. We couldn't understand why.
I was always at work while this was going on and never knew any of this was happening until people bought the house next door and told me.
A black friend came over to help me show "Binky" that his master was fine with black people. And I made it so that the dog could not see out the window.