He was rescued from the property and taken to a vet for treatment.
The dog weighed just 15.5kg and was discovered to have a severe flea infestation, a severe worm burden, very overgrown claws, and open raw pressure sores on his front legs and rump, the SPCA reported. The organisation's vet said the dog would have died of starvation if left in the hands of its owner.
When Kelly was questioned about the dog, he admitted he had lost interest in his pet.
"He had thought about having the dog put down but hadn't done anything about it. He knew the dog wasn't well, as he noticed it had stopped barking, had lost muscle, and its movements had become shaky, but he had not sought any expert advice or veterinary treatment for the dog," the SPCA said.
Bob Kerridge, executive director of SPCA Auckland, said it was a "very sad case".
"An animal who depended solely on his owner for attention and affection was chained up, with no food or shelter, simply because that owner had 'lost interest' and ignored his responsibilities," he said.
"Losing interest does not give any human the right to neglect an animal in a backyard to starve to death, and the court's five-year disqualification from owning any animals will hopefully ensure such [an incident] will not occur again at the hands of this person.
"Unfortunately, the dog has since had to be humanely euthanised due to serious behaviour problems that meant we could not responsibly re-home him. This is a great pity and almost certainly the result of the neglect that he suffered at the hands of his former owner."