At the appeal hearing in the Frank Cody Lounge yesterday, Ms Wolterbeek said she got Thor when he was a year old as a companion for an older dog.
He had been properly trained in obedience and agility, and also in search and rescue type tracking.
As a result she had full confidence Thor would never act aggressively.
He took part in organised dog walks with other dogs and owners.
"The group would never accept aggressive dogs," Ms Wolterbeek said.
Thor had been seriously injured as a result of the dog fight and had been left with a limp.
Ms Wolterbeek said he was not the dog he was before.
"He is now very wary of other dogs and his surroundings," she told the committee.
"When he meets other strange dogs he keeps his distance, even the walking group dogs," she said.
Mr Stewart, who was walking Thor in Northcroft Rd, Rangitumau, on the day of the attack, said he had been behind Thor as they approached a corner where the fight broke out.
It was unclear how it had started but he described Thor as being a "big sook".
" I love him to bits," he said.
Thor loved to play, especially retrieving pine cones while on walks, and that activity would have to cease if he was forced into a muzzle. Thor had been walked around at Martinborough Fairs for three years without incident.
Ms Wolterbeek said should the German shepherd be muzzled it would give the wrong impression about the nature of a dog who was not aggressive.
"When we go on holiday we get a pet sitter. Do you think we would be able to get one if a dog is classed as menacing?
"If we go to a beach, he would have to be muzzled. He couldn't even play, his life in public would be over," she said.
The hearings committee reserved its decision immediately after evidence was given by Ms Wolterbeek and submissions by Mr Vanderklok.
During submissions, Mr Vanderklok referred to a report from a Masterton vet that not only listed the dog's injuries in the wake of the fight but made comment regarding the injured dog's demeanour.
Dr Caroline Benson said that during her work on Thor he was "well behaved and not aggressive towards me or the staff at my clinic".
A decision on the appeal is expected within a week or so.