"Where there's a lack of training, or when there's very few boundaries, a dog turns into a wild child," said Ms Kiernan, who runs Carterton-based K9 Wise.
"I have worked with dogs who had been aggressive or where there were problems with biting. The dog was not being handled properly and the owners had no idea how to train it."
She said attacks occurred when a dog was under stress, which could be caused by inadequate training or overly aggressive training methods - such as using a choker chain or an electric collar - a lack of socialisation, or hormone levels when a dog was not de-sexed.
In some cases where larger dogs, such as pit bulls or Staffordshire terriers, became aggressive "people get these dogs and end up out of their depth," she said.
"They don't do any training, because the dog doesn't want it, so they get blindsided by it.
"Also, you get people who chain up their dogs and use them as yard ornaments. They have no stimulation."
Ms Kiernan said she had noticed a culture of aggressive dog ownership in Wairarapa, where a person would use a dog to cultivate a macho image, which was particularly true with some pit bull owners.
And because of the pit bull's "bad rap" as an aggressive dog, they had become more appealing to criminal owners and gang members, Ms Kiernan said.
"Pit bulls actually have a fantastic temperament around humans. They used to be called 'nanny dogs' because it was completely safe to leave your children with them. But now we've got people doing backyard breeding [for] the complete opposite temperament. Because when you demonise a dog, it attracts the lowest common denominator."
Masterton veterinarian Jacques van Zyl agrees the key to reducing dog attacks is comprehensive training by owners.
"It all depends on the way the dog is managed. It's not a problem with the breed itself," said Mr van Zyl, who works out of Chapel St Vets.
"Things like dog obedience are very helpful. Those bigger dogs need some firm handling, especially when out walking. That sheer brute strength can be very frightening to people who are used to pocket-sized dogs."
A fully grown pit bull could weigh up to 80kg.
"They're pure muscle. That's a lot of dog," Mr van Zyl said.
"When you've got such a strong, muscular dog, it needs to know who's in charge."
Ms Kiernan says an emphasis on dog training is more effective than banning dog breeds outright.
"In the countries where they've tried breed-specific legislation, it hasn't worked," she said.
"It hasn't reduced the number of bites.
"And when breeds are banned, people just go underground."
