In his 19 years, the golden retriever/"some black dog" cross has worked on building sites, lived in Sydney, suffered the indignity of a full-body shave, survived cancer and has watched his human family grow from one to four.
JD's owner, David McNeill, credits his longevity to love and fitness.
"Right from day one, he's always been a mate. He's part of the family."
Gardens Vet Clinic veterinarian Russell Brown said it was "extremely rare" for a dog to live to such an age.
In 40 years of practice, it was "extraordinary" to even come across dogs that were 17 or 18.
The longevity of dogs varied widely between breeds, with small dogs such as terriers sometimes living to about 15 or 16, while the giant breeds, such as St Bernards, did well to get to 10.
Mr McNeill said he had initially declined the offer of a puppy, but when his friend brought the litter on to a building site where he was working he found himself saying "I will have one, then".
Nameless for "quite a while", JD found his own name when at a party he got himself drunk after lapping up a dropped glass of Jack Daniels.
"He curls his nose up when he sniffs it now. He learned his lesson young."
JD soon proved himself a handy worker on building sites, fetching dropped tools and quickly learning a range of tricks.
Along with his "dad", JD became a regular at the Valley Lodge Hotel.
In 2000, JD emigrated to Australia, taking up residence in Sydney, where a brush with the local wildlife gave him tick poisoning and he had to suffer a full-body shave which left him looking like a wrinkled puppy.
After being "best dog" when Mr McNeill married Tania, the family came back to Dunedin in 2005 and grew with the additions of children Keira and Rylee.
"He's been bounced on, stood on, had his ears pulled and his eyes poked. He just gives me a look that says `Help'," Mrs McNeill said.
In 2007, JD was diagnosed with cancer and given six months to live.
He fought it off and is still going strong.
The family have traced JD's age from the diary entries of Mr McNeill's sister, but are trying to track down the man he came from so they can confirm it exactly.
