Greenies, the nation's best-selling dog treat, has got some dog owners seeing red. The tooth-brushed shaped dog chew, designed to combat bad doggy breath and prevent periodontal disease, is marketed as “the original smart treat,” but 13 dogs have died after a Greenie got lodged in their esophagus or intestine, prompting some pet owners and vets to ask whether Greenies are such a good idea.