Russell Mendoza and Tony Campbell are on trial in Auckland District Court, accused of a "commando exercise'' in which 33 of Mr Hargreaves' dogs were shot dead on a rural property near Wellsford in January, 2010.
The pair have denied four charges of wilfully ill-treating an animal and firearms charges.
Mr Hargreaves said he heard dogs squealing and making noises
Mr Shaw asked Mr Hargreaves if he went inside the cage.
"I was too much in shock and horror. I guess I couldn't contemplate it. I just opened it and looked. I couldn't even walk in the cage.''
Earlier he told the court that he had agreed to some dogs being destroyed but certainly not all of them.
Mr Hargreaves said that in the days leading up to the shooting he himself had put down two of his dogs after he heard one of his dogs had mauled Mendoza's dog. He had also caught another dog in a neighbour's chicken coop.
Mr Hargreaves said he took Spots and Lumps out of their cage, away from the other dogs, put the gun to their heads and pulled the trigger.
"The right way with one bullet to the head.''
He said on the day of the shooting that he had gone to Mendoza's house to see him after receiving a phone call from a friend who told him "Mendoza was out to get me''.
He said he and his friend went to Mendoza's house but stopped at the gate because Mendoza's wife was yelling: "get the f*** off the property''.
"Somebody was saying: 'I'm going to break your face'.''
Mr Hargreaves said he also heard Mendoza's wife say: "Kill them all''.
He said he went back home and decided to make a "farmland offer'' which he told the court amounted to an agreement to have some of his dogs put down.
Mr Hargreaves said Mendoza and his friend Campbell - known as Tussock - turned up with guns and he moved away after signing a note giving the men permission to shoot his dogs.
"They were my family and friends. I couldn't stand there and watch them being put down.''
But he told the court he did not expect any of the puppies to be shot and certainly not all of his dogs.
His evidence is continuing.