Graphic video footage showing the torture and beheading of a 1-year-old dog has been circulated among teenage school students.
The attack on the helpless dog has been labelled "New Zealand's worst" by animal welfare activists. Police are hunting those in the video.
The sickening images show a man tying the red nose pitbull to a tree while three people, including a woman and a child, look on and laugh as it tries to escape.
The man bashes the puppy's head several times with the back of an axe before taking more than a minute to cut off its head with a machete.
The puppy yelps in pain while the man jokingly says "dog on death row, dog on death row".
Students at Manurewa High School were offered counselling after watching the two-minute video depicting the torture and mutilation.
Manurewa High School principal Salvatore Gargiulo said a 16-year-old female student brought the disturbing video to his attention in October last year. The student contacted animal rights group Paw Justice, which has been working closely with police to find the people involved.
Gargiulo warned students about the serious consequences of sharing abusive content.
"We made it clear to the kids that possessing a thing like that was a criminal offence and that if you had it on your phone then you ran the risk of being convicted for a crime," Gargiulo said.
Students' phones were randomly checked to ensure the horrific video had been deleted. "We understand that stopped it immediately," he said.
None of the students opted to take up the offer of counselling.
Community constable Corey Rees said it was possible the video was filmed in Tonga - where dog meat is eaten - but did not rule out that the footage had been taken in New Zealand.
"Because of the massive population of Tongans in New Zealand, you can't say it doesn't happen," Rees said.
"I thought it was disgusting, even if culturally they do eat dog, but it was the manner of how they were putting it down."
Paw Justice co-founder Craig Dunn said it was the worst animal attack he had seen in New Zealand.
"There's a lack of empathy in this video towards animals. There's no remorse, nothing, it's horrific," Dunn said.
"People who abuse animals will go on to be a nightmare in society."
Dunn said the killing of a domestic animal might be acceptable in Tongan culture but it was not acceptable in New Zealand.
"In New Zealand, we don't eat our pets."
SPCA executive director Bob Kerridge had not seen the video but said anyone who wanted to film cruelty towards animals had a "sick" and "corrupt" mind.
"You have to wonder what mentality would, firstly, perform such an act and, even worse, film it for others to see.
"That shows a very sick mind and a very corrupt mind," Kerridge said. "We have had all sorts of cases of, firstly, ethnic, and secondly, quite horrific, offences to animals, but when you commit it to video and circulate that video, particularly to a school with innocent minds, that's a different crime."
Counties Manukau Community Law Centre manager Emosi Koloto said it was not acceptable in Tongan culture to inhumanely kill animals or eat domestic pets.
"I'm really, really mad about these kind of stories. What I know about Tongans is the same as Pakeha here, they don't accept people eating dog meat.
"You will not see a dog or cat in any Tongan food. If it's happening it has got to be from someone who is stupid or silly because it's not acceptable in Tongan custom."
A charge of wilful cruelty to animals holds a maximum penalty of five years in jail or a $100,000 fine.
ILL-TREATMENT OF ANIMALS
February, 2009 - Dunedin
An 18-month-old Jack Russell was killed after being strangled, hit with a spade and forced to drink petrol. Jeffrey Robin Hurring, 19, was sentenced to 12 months in prison for wilfully ill-treating an animal.
March, 2009 - Wellington
Two kittens had their paws cut off believed to be by children, aged 10, using a knife or scissors. The kittens survived but had major surgery to have their hind legs and part of their hips amputated.
September, 2009 - Gisborne
Te Ahu Mankelow, 31, fed five live kittens to his pit bull dog when he went to a party. He was jailed for seven months.
November, 2010 - Auckland
David Hamuera Snook was sentenced to two years and four months in prison after he tore the head off a kitten in front of his former partner and her children.
December, 2010 - Kaikoura
Twenty-three seals, including eight newborn, were clubbed to death on the Kaikoura coast.
Anyone with information about the video or those involved can contact Auckland Police on (09) 571 2800.