Nearing age 21 this male dachshund – terrier mix Otto is 20 years and 8 months old. Which is about 145 in human years guesses Lynn Jones, the owner of Otto. She has owned him since he was six weeks old and now has seen him grow through his dog years as the oldest living dog. Her and her husband contacted Guinness and Otto is being acknowledged for his old age in the Guinness World Records.