A petition to save Chip the puppy from being put down has more than 10,000 signatures.
Electrician Jonathan Robins started the petition after finding Chip and handing him over to Auckland Council animal management, only to hear that he was likely to be put down.
Some of the petition's 10,021 supporters commented on the change.org site, with one saying the world was "a cruel enough place without murdering an innocent pup".
Mr Robins said today he had also spoken to animal organisation Paw Justice, in the hope that they could help remove Chip from Henderson Animal Shelter.
Mr Robins, 29, found the puppy in a rubbish bin on Williamson Ave in Grey Lynn on Saturday and cared for him until he was picked up and taken to the shelter.
"I just pulled over to put rubbish into a bin; then lo and behold a little head popped out at me."
The pup was playful and happy, he said, despite being skinny.
Chip has not put on any weight in the last four days, Geoff Keber, Auckland Council's manager of animal management said today.
Shelter staff members were worried about the puppy's health as he remains very underweight, Mr Keber said.
Mr Robins says he was told by the woman who collected the puppy that Chip was likely to be put down as he was part-pitbull.
He said he would never have called them if he knew this would happen.
Mr Robins attempted to get Chip back, but was told the pup was in isolation and no one was allowed to see him.
"I wanted to just remove him from the shelter and take him home to no luck."
Mr Keber said it was Council's policy not to adopt out dogs that were "wholly or predominantly" pitbull, because of their ability to inflict major injuries, particularly to children.
It is difficult to tell what breed a puppy is, he said, but Chip appeared to have "Sharpei traits".
The council's animal management staff has "a passion for dogs", he said.
"No one is happy to put a dog down, no one wants to."
The "most outrageous" thing about Chip's case, Mr Keber said, was that "some person has owned Chip and let him get into the state he is in".
The council must keep dogs for seven days to allow an owner to come forward as well as assess an animal's suitability for adoption.