Golden retrievers key to lifetime dog cancer study - Article Photos 2/5

This 2012 photo provided by Colorado State University, shows a golden retriever, Louie Mesinger, in his backyard during the summer in Boulder, Colo. The Golden Retriever Lifetime Study will be the largest and longest study of dogs ever conducted. For Louie and 2,999 other purebred golden retreivers who are chosen over the next two years, their lives, usually a 10-to-14-year life span, will be tracked for genetic, nutritional and environmental risks to help scientists and veterinarians find ways to prevent canine cancer. (AP Photo/Colorado State University, Josh Mesinger)