Gibson, the world's tallest dog has died from cancer at the age of 7. The Harlequin Great Dane was diagnosed with osteosarcoma, an aggressive, bone cancer in April. His owner, Sandy Hall made the very difficult decision late last week to have Gibson euthanized to end his suffering. When a tumor was discovered in his right front paw, his whole leg was amputated in hopes of keeping the cancer from spreading. However last week Gibson's owner, Sandy Hall, learned that the cancer had spread to his spine and lungs. Gibson made it into the Guinness Book of World Records for his unmatched height of 42.4 inches.