A 26-year-old mongrel living with an Aboriginal family in Australia's Outback has the potential to become the world's oldest living dog, a newspaper reported yesterday. Jerry, an Australian cattle dog-bull terrier cross, will next month turn 27, the equivalent of 189 years for a human, said Royal Society for the Prevention of Cruelty to Animals veterinarian Honey Nelson in Sydney's Daily Telegraph. The oldest living dog in the 2004 edition of the Guinness World Records is Butch, a 27-year-old beagle in Virginia.