A group of 3,000 golden retrievers from across the U.S. are taking "good dog" to a whole new level. Their checkups could help scientists beat canine cancer. These golden retrievers are enrolled in the Morris Animal Foundation's Golden Retriever Lifetime study, the U.S.'s largest veterinary study ever. It researches what increases the risk of dogs developing cancer and other health problems, and ultimately aims to help dogs live longer, healthier lives. More than half of golden retrievers end up with cancer, the foundation reports, so that's why they're the specified subjects in this study. These good dogs need a little human help to make a difference, though.