Terah Leder started to record video on her phone.
"I was trembling, freaking out. I couldn't believe what I had just seen," said Leder.
The video lasted just over two minutes. In it, Leder says, you can see a groomer handling a dog aggressively as the fur was trimmed around its head and neck.
"It was crazy," said Leder.
After explaining to management what happened, Leder then waited outside for someone to come pick up the dog.
"If that were my dog I would want to know that that happened to her," said Leder.
She didn't know who the owner was. She waited an hour before Brooke Vowers exited the store with the dog. Vowers had dropped off Boo hours before and had no idea anything unusual had occurred. She said she was stunned when Leder told her what she saw.
"I was like, 'Are you kidding?' Just kinda like confused, you know?" said Vowers.
Only later did Vowers watch the video. She then posted it to Facebook where it went viral.
"That was just a tidbit of the video. I'd hate to think what would happen in four hours," Vowers said. "The fact that that could happen to anyone else's dog is just concerning to me."
Vowers says watching the video of the way her two-year-old Shih Tzu was treated makes her sick.
"If this happened to my dog, it probably happened to other dogs, and I don't want it to happen to future dogs," said Vowers.
She is thankful, however, for the kindness of this stranger who spoke up for her furry friend. Without that, she says, no one might ever have known what happened.
We've tried repeatedly and unsuccessfully to reach the groomer.
PetSmart was quick to respond when we began asking about this incident. A spokesperson said the treatement is "completely unacceptable and will not be tolerated".
That employee has been fired, the company added.
There is no criminal investigation at this time.