McDonald was on bail for the first attack when on October 26, 2010, he used the same dog to threaten a police officer who was arresting one of his friends at a Tauranga intersection.
When a police officer approached McDonald, he gave a false name and tried to walk off. When it became clear the officer was going to conduct a background check, McDonald started to loosen the chain and allowed the dog close enough to lunge at the officer.
He was forced to jump a fence into a nearby garden to save himself.
The officer had to pepper-spray the dog a second time before it ran off.
Later that night, during a row between McDonald, his partner and several other people at a Tauranga house, McDonald set the dog on his partner and as she backed away the dog latched on to her right leg.
She suffered a 3cm by 5cm gash to her leg but was reluctant to make a complaint because she did not want McDonald charged.
The dog, which has since been destroyed, was not owned by McDonald but he was deemed by law to be the owner as it was under his control during the three attacks.
Crown prosecutor Hayley Sheridan told the court she had been unable to find a deliberately ordered attack in New Zealand case law.
Defence lawyer Glenn Barnett cited a psychologist's report which found McDonald had underlying mental issues that may have been affected by a head injury he received as a child and had "unresolved issues" from the violent death of his father in 2005.
McDonald's grandfather, Jack McDonald, broke down before Judge Robert Wolff as he offered to take him into his Te Kaha home and re-introduce him to the local marae.
His grandson had assured him he could "turn his whole life around" and would "have to follow the rules" at his house, with no drugs, alcohol and "not even a bloody cat".
"I'm prepared to help him whatever the consequences are."
Judge Wolff acknowledged the offer, and encouraged McDonald to seek help from his family, "because they will look after you ... and they will love you".
Tauranga City Council animal services team leader Brent Lincoln said it was the first case he knew of where a dog had been used as a weapon.
"I guess the underlying thing with the pitbull-type breed is they are very efficient at what they do - if a pitbull bites, it inflicts significant injuries."
Nationally, pitbulls accounted for 1.5 per cent of the dog population and were responsible for 18 per cent of attacks on people, he said, but almost every incident was a reflection of the dog's ownership.
