The plans have ignited an e-mail campaign by breed rescuers and pet foster parents.
The new West Valley City facility, to be located at 4400 West and 3500 South, plans to use this method only when animals are diseased, dangerous or feral and unable to be handled by workers, according to Animal Services Operations Director Kelly Davis.
He said from the animal's point of view, they are still in a cage, and "eventually they just go to sleep." Staff would move them about using long-handled poles with leads on the ends.
One e-mail, from Marylin Segall, a longtime animal advocate and rescue volunteer, said: "I urge you to reconsider the installation of a gas chamber. . . . Euthanasia by carbon monoxide poisoning is not a humane, painless or quick death for our homeless companion animals."
Likewise, John Snyder, vice president for companion animals for The Humane Society of the United States, expressed his concern.
"It's a step backwards to use a gas chamber at this day and age. Every shelter that has access to sodium pentobarbital should use it as their only method of euthanasia. . . . Leave the 1970s technology behind."
Davis said he received more than 700 e-mails opposing installation of the chamber within the facility.
"Injection is the preferred method of euthanasia. However, there are circumstances when a chamber is appropriate," he said.
"I've seen both methods work. And in some cases, I've seen less stress involved in the chamber than when you are handling the animals."
Plans for a new animal shelter have been in the works for several years. In the current 30-year-old facility, about 1,000 animals were euthanized in 2006. That number rose slightly last year to 1,100, Davis said.
At 4,200 square feet, the shelter is one of the state's smallest and most crowded.