The 6-year-old was sentenced to death last week in the Thames District Court after attacking a woman at a Whitianga bed-and-breakfast last October.
Jennifer Layton, who pleaded guilty to owning a dog that attacked a person, had been considering going to theHigh Court in a bid to save him.
But after another person laid a complaint about an incident involving Boris late last year, she gave up any further legal action and said goodbye to her beloved dog, who was destroyed on Wednesday morning.
"They [the Thames Coromandel District Council] were entitled to come and take him away with a police escort at any time of the day," Mrs Layton said. "I was beside myself. It was just awful."
Mrs Layton said she felt "dead", having spent $3800 on training for Boris with animal trainer Mark Vette to rectify his issues and change his living space.