The Palmerston North City Council is impounding hundreds of dogs each year but more than half are being returned to their rightful owners.
Head of environmental protection services Wayne Jameson said last year 594 dogs were brought into the pound with 50 re-homed and 169 euthanised.
The chosen method for those who were put to sleep was a "humane" injection given by a vet.
"For as long as I can remember we've always used this method," he said. "We work in an urban area and none of our officers carry firearms."
A petition is circulating the internet calling for a Northland council to stop using shooting as their method of euthansia. It alleges the pound's dogs are lined up together and shot one by one.