In a letter posted on Facebook about the pit bull Pandora by the dog's owner, city prosecutor Ellen Gerber says the evidence doesn't support a charge under the city's animal control by-law.
The attack happened Nov 20 around 1 p.m. PT when the pug's owner was approached by a woman, who was walking her pit bull in Kitsilano Beach park.
When the dogs approached each other, the larger pit bull suddenly bit down on the neck of the smaller dog.
Unable to separate the animals, the 72-year-old owner of the pug pulled out a folding knife he was carrying and stabbed the pit bull, killing it.
The pug was rushed to a veterinary hospital for stitches to its neck. Animal control officers also attended the scene.
Gerber says, even though the pug was being walked off leash, charges aren't appropriate.
"In light of the impact of Pandora's death on all persons involved, I am satisfied that further infractions are unlikely," she writes, "and that any conviction would result in a very small or insignificant penalty."
In a Facebook post, the pit bull's unsatisfied owner asks supporters to write letters to the city and says she is still hoping Crown counsel will consider criminal charges of animal cruelty.
However, at the time of the incident, Vancouver police said it didn't believe there was any basis for criminal charges.