Indeed, the sudden change in the way people treated her hit the dog hard.
"I can see it in her," Hamilton says. "She's friendly. She loves people. And all of a sudden, no one wanted to talk to her. Everyone wanted to cross to the other side of the street."
At times, people yelled at Niki - "Get rid of that vicious thing!" - and even threw stones at her.
It turned a dog who was once a beachcomber - bounding along shorelines, offering big, bouncy greetings to everyone she met - into a public enemy.
All because of the way she looks. Today, with a pit bull ban looming over Montreal, Hamilton sees the same sad potential for countless more dogs - especially since the wording of how the city determines a pit bull is so vague.
"This doesn't just affect pit bulls," she says. "This could affect your dog in a heartbeat. If you have a short, blocky-headed dog, your dog can be affected."