A beloved dog who sniffed out her owner's cancer has passed away from the disease herself. Heidi the German Shepherd/Lab mix made headlines last year when her owner, Anne Wills, credited the dog's odd behavior with saving her life. Heidi, a trained search and rescue dog started acting strangely last February. Anne took Heidi to the vet, but he couldn't figure out what was wrong. Then Anne decided to go to the doctor herself. To her shock, a cat scan revealed that she had Stage 3 lung cancer.