My next-door neighbors, actually the other half of my duplex, have a Rottweiler who is just the sweetest thing, she's great with my twins, stronger than any human I've ever met (I certainly couldn't hold her if she chose not to let me) - and she's afraid of my kids' black stuffed animals! They have a big (taller than they are) cute stuffed fluffy black bear - the dog won't even stay in the yard if it's on the porch - and a little black doggie that I think the Rottweiler thinks is out to get her (and she doesn't argue). It's a howl. She doesn't seem to be afraid of any others, just the black ones. Go figure...