At first glance, Pusuke might not look like a particularly special dog - a humble male mixed-breed owned by a housewife in Sakura, Japan. But the seemingly common canine is now 25 years old, a life span so extraordinary that he may be recognized by Guinness World Records as the world's oldest living dog.

Pusuke is so long in the tooth that his age in "dog years" is equivalent to more than 120 years for a human.

His owner, Yumiko Shinohara, 41, will soon begin the application process to have him certified as a world record holder.

Guinness currently lists the oldest living dog as an Australian Kelpie living in Melbourne that, as of March, was 21 years and 3 months old.

The oldest dog on record is believed to have lived 29 years and 5 months.

Pusuke was born in March 1985 at Shinohara's relative's home in Sakura. His parents were a midget Shiba, a species indigenous to Japan, and a mixed-breed.

His age can be verified as he was placed on the local government's pet register on April 1 that year, and was inoculated against rabies and other diseases.

Pusuke takes a meal every morning and evening, and loves the occasional piece of cake as a snack. Even at his age, he never fails to keep up his daily exercise routine of a walk in the garden.

His evidently strong constitution was challenged two years ago, when he was seriously injured in a traffic accident. In the summer of 2008, he was run over by a car and suffered the rupture of several internal organs.

Shinohara was told by a veterinarian that Pusuke might not survive, but after emergency surgery that lasted five hours, he pulled through.

After a convalescence at the veterinarian's clinic, Pusuke came home and resumed his post as guard dog, barking at strangers as they passed the Shinohara home.

Nicknamed Pu, the protective pooch is always waiting near the front door to welcome family members when they return home.

"He was born when I was 16 years old, so he's just like my son," Shinohara said. "I don't know why he's managed to live so long, but I'll keep caring for him so he'll be able to live until he's 30."