" But it's the work that gives these dogs joy more than any amount of nurturing or the fresh air of their 20th-floor haunt. They begin to bark wildly when visitors walk onto the penthouse deck. When Busgith pulls Nicky from the cage, she calms down immediately, sitting serenely next to her handler as he strokes her brow. Then, on command, Nicky bares her formidable teeth. Her ears lie back. She growls, lunges and works herself into a ferocious lather. Busgith then utters another word, and Nicky quietly sits next to him again, calm as before. Her fierceness turns on and off like a light switch. "You could play with them but not before they get your scent," handler Jonathan Hamilton said. "But you need to know that the way they get your scent is to smell your crotch.