Thirty-three unregistered dogs from one property have been slaughtered in a dispute between neighbours in rural Wellsford, north of Auckland.
The argument was apparently sparked when one man discovered his fox terrier had been mauled to death by another animal.
The fox terrier's owner, Russell Mendoza, accused one of neighbour Rowan Hargreaves' thirty-three dogs as the animal that mauled Mendoza's dog.
The SPCA has been told Mendoza then forced Hargreaves to sign a letter saying he agreed to the shooting of the rest of the animals.
However, Hargreaves later discovered that there was no actual sighting of one of his dogs killing the fox terrier, the Rodney District Council confirms.
The Rodney District Council also told ONE News they had never received a complaint about Hargreaves' dogs.
Hargreaves' friend Richard Hawkings, who watched the killing unfold, says it is something he will never forget.
"The sound, it's psychologically done something to me... it was horror."
The SPCA says the sheer size of the dog massacre puts it in a completely different league to anything it has dealt with.
The SPCA also says they are still considering laying charges.
Six dogs, including four puppies hiding under their mother, survived the killings.
The SPCA is investigating and inspectors have been to the property.