My dog howls whenever she hears Piano Man by Billy Joel. That's the only song she's ever reacted to, and she does it every time. Her ears perk up as soon as she hears the piano in the intro, and she starts howling when the harmonica starts. She doesn't stop until the song ends. I have no idea why she does this, and when I told her vet about it, the vet just shrugged and said, "I've always liked Billy Joel, too."