Bill Malcolm, of Oamaru, had been out feeding pet lambs at his woolshed on Wednesday night when he noticed a lamb with blood on its shoulder.
He then saw all the ewes and lambs huddled in fear in the corners of the paddock, along with another dead lamb.
An injured lamb was curled in a heap but stood up when he arrived.
"All the flesh was ripped off its front leg," Mr Malcolm said.
It did not initially cross his mind that it could have been a dog attack, but he changed his mind when he saw two dark shapes at the bottom of the paddock.
He had come across the short-haired pointer and the black-and-white huntaway on his farm before, and taken them to the pound.
This time, they had two dead lambs beside them.
"When I found [the dogs], they didn’t know they had done wrong. To them it was just a game," Mr Malcolm said.
He took the dogs with him and called animal control.
A younger version of himself would have shot them on the spot, Mr Malcolm said, but he was older and more laid-back and wanted to follow the correct processes.
Being a dog owner came with responsibilities and the issue was pretty straightforward, he said.
The council needed to show the behaviour of both the dog owners and dogs could not be tolerated and should use all available tools to stop it happening again, he said.
In the "hellish and very traumatic" attack, five lambs died at the scene and two were so badly injured they had to be put down immediately, Mr Malcolm said.
He had to euthanise another seven lambs yesterday morning after they were seen by a vet.
Only two lambs survived the attack and the mothers of the dead and dying lambs were too scared to be with their offspring in their final moments, Mr Malcolm said.
Waitaki District Council senior compliance officer Tristan Hope said animal management officers were investigating the incident as a "serious attack by dogs on stock".
The owners had been identified and a decision on any enforcement would be made at the conclusion of the investigation.
