I first met Lucy at my local monthly “My Dog Can Do That” competition in January of 1998, at the SPCA in Monterey, California. She was easy to spot – a merle Great Dane with lovely natural ears, who literally towered above the competition. Lucy was attentive, responsive, performed even the most advanced MDCDT behaviors with ease, and consistently placed in the ribbons. It surprised me, then, when a few months later I heard Lucy had started threatening humans, and her aggression was escalating. This was not appropriate behavior for any dog, but particularly disturbing in one of Lucy’s size, with her potential for causing serious harm.