The owner of a miniature pinscher says her dog was attacked and killed by a pit bull in Vancouver on Saturday.

Mia Johnson says she is devastated by the loss of her dog, Yuri, and was shocked when a Staffordshire bull terrier — a breed commonly referred to as a pit bull — lunged at her two miniature pinschers while she was walking them on Dunbar Street at 10th Avenue.

"How would you know if it would be a violent dog you meet, how would you know?" she asked CBC news Monday.

'We couldn't get it to let go'

Johnson says she was out for a walk with her daughter and two dogs when a woman walking a pit bull approached.

'I just held him against me. I held everything in with my hands, against me...' - Mia Johnson, recounting pit bull attack aftermath

Johnson says the larger dog was on a leash, and appeared to be wearing a muzzle but also seemed out of control.

She says the dogs' leashes became tangled, and at some point the larger dog's muzzle came loose, allowing the pit bull to grab her much smaller dog in its jaws.

"We couldn't get it to let it go, I remember I was banging it on the top of it's head as hard as I could," she said.

Johnson says once the dogs separated, she was horrified to discover her dog appeared to have been disemboweled, and was howling in pain.

Laurel Owen - therapy dog killed by pit bull - Nov. 3, 2014

Laurel Owen holds her family's remaining dog, Mary, while mourning the loss of Yuri. (CBC)

"I just held him against me. I held everything in with my hands, against me, and he was alive. He was just letting out these terrible screams, and I just kept holding him as hard as I could," Johnson said.

Johnson says her daughter, Laurel, who has Asperger syndrome and an anxiety disorder, chased the pit bull's owner.

"My daughter was running after her, screaming, 'You're a murderer, you're a murderer.'"

She says Yuri was a therapy dog for Laurel, who has spent the last two days holed up in her room, trying to process the loss of her beloved pet.

A calm little dog

"She just has so much trouble with anxiety that she couldn't really do anything, and he made her feel like there were two of her, and she wasn't doing everything alone."

Miniature Pinscher killed by Pit Bull

Yuri was not only a comfort to Laurel, but was also a volunteer therapy dog at a Vancouver palliative care centre.

Johnson says Yuri was also a volunteer therapy dog at a Vancouver palliative care centre, who would comfort patients on his weekly visits.

"He would get up on their laps and he would just sit there, and just be loving them, and sometimes he would lie on somebody's bed next to their head if they were in their final stages. He was just a calm little dog," she said.

The City of Vancouver confirms it has seized the pit bull and bylaw officers are investigating.

With files from the CBC's Richard Zussman and Stephanie Mercier